METHOD OF MAKING NICOTINAMIDE RIBOFURANOSIDE SALTS, NICOTINAMIDE RIBOFURANOSIDE SALTS AS SUCH, AND USES THEREOF

FIELD OF THE INVENTION

[0001 ] The present invention relates to a method of making nicotinamide ribofuranoside salts, in particular pharmaceutically acceptable nicotinamide ribofuranoside salts. The invention further relates to nicotinamide ribofuranoside salts as such, in particular carboxylic acid salts in crystalline form, and their use in nutritional supplements and pharmaceutical compositions.

BACKGROUND OF THE INVENTION

[0002] Nicotinamide riboside (nicotinamide-p-D-ribofuranoside; CAS no 1341 -23-7)

is a precursor of nicotinamide adenine dinucleotide (NAD7NADH) and nicotinamide adenine dinucleotide phosphate (NADP7NADPH). In addition, nicotinamide riboside is a niacin (vitamin B3) equivalent.

[0003] Nicotinamide riboside has been reported to increase NAD ⁺ levels in liver and skeletal muscle and to prevent body weight gain in mice fed a high-fat diet. It also increases NAD ⁺ concentration in the cerebral cortex and reduces cognitive deterioration in a transgenic mouse model of Alzheimer’s disease. For these reasons, nicotinamide riboside salts have been suggested for use in nutritional supplements and pharmaceutical compositions. In fact, the chloride salt of nicotinamide-p-D-ribofuranoside is a commercially available nutritional supplement. [0004] However, broad application of these compounds as dietary supplements has been limited by production methods which are low in yield, have poor stereoselectivity, and/or employ expensive and/or hazardous reagents, or which lead to pyridinium salts comprising pharmaceutically unsuitable counter-ions. Therefore, many known synthetic methods are not amenable to large-scale, commercial syntheses.

[0005] WO 2016/014927 discloses a crystalline form of nicotinamide riboside chloride which is described to have advantageous properties, e.g. ease in purification, relative to amorphous forms of nicotinamide riboside salts.

[0006] WO 2017/218580 discloses synthetic methods for the preparation of nicotinamide riboside salts including salts comprising a pharmaceutically acceptable anion. The methods may include converting one pharmaceutically acceptable counter ion of the nicotinamide-p-D-ribofuranoside moiety to another pharmaceutically acceptable counter-ion through ion exchange chromatography or salt exchange reaction and precipitation. In certain embodiments, the described methods include converting a salt of nicotinamide riboside or analogs thereof, where the salt is not the chloride salt, to the corresponding chloride salt.

[0007] WO 2015/186068 A1 discloses the reaction of nicotinamide-p-D-ribofuranoside triflate with sodium methylate in an ion exchange reaction to afford crystalline nicotinamide-p-D-riboside chloride.

[0008] CN 108774278 discloses the reaction of nicotinamide triacetylribofuranoside triflate with a base in order to deacetylate the furanoside. Subsequently, the deacetylated product is treated with an acid to give the corresponding salt product.

[0009] However, for given applications, alternative pharmaceutically acceptable salts of nicotinamide riboside are desirable as well as methods that allow for their preparation in an inexpensive, efficient and convenient way.

OBJECTS OF THE INVENTION

[0010] Accordingly, there is a need in the art for pharmaceutically acceptable nicotinamide ribofuranoside salts, preferably crystalline salts, and methods for making pharmaceutically acceptable nicotinamide ribofuranoside salts in high purity and yield at low costs and on an industrial scale.

SUMMARY OF THE INVENTION

[001 1 ] This object was achieved with a method using nicotinamide-p-D-ribofuranoside bromide or nicotinamide-p-D-ribofuranoside trifluoromethanesulfonate as starting material for making nicotinamide-p-D-ribofuranoside salts other than the bromide and triflate salts via salt metathesis comprising counter-ion exchange.

[0012] Nicotinamide-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-p-D- ribofuranoside fluorosulfonate or nicotinamide-p-D-ribofuranoside perchlorate are other suitable starting materials in the methods according to the invention.

[0013] In yet another embodiment, nicotinamide-p-D-ribofuranoside chloride or iodide are used as starting materials in the methods according to the invention.

[0014] In one embodiment, the use of nicotinamide-p-D-ribofuranoside bromide and nicotinamide-p-D-ribofuranoside trifluoromethanesulfonate and in particular nicotinamide- p-D-ribofuranoside iodide as starting material is preferred.

[0015] In a preferred embodiment, nicotinamide-p-D-ribofuranoside salts are available via the methods according to the invention, wherein the salts advantageously may be provided in crystalline form.

[0016] According to a first aspect, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt, comprising step (A):

(A) subjecting nicotinamide-p-D-ribofuranoside bromide, nicotinamide-p-D- ribofuranoside chloride, nicotinamide-p-D-ribofuranoside iodide, nicotinamide-p-D- ribofuranoside trifluoromethanesulfonate, nicotinamide-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-p-D-ribofuranoside fluorosulfonate or nicotinamide-p-D-ribofuranoside perchlorate to salt metathesis comprising counter ion exchange to afford the nicotinamide-p-D-ribofuranoside salt. [0017] The nicotinamide-p-D-ribofuranoside salt to be made by the method is not a bromide, a iodide, a triflate, a nonaflate, a fluorosulfonate or a perchlorate.

[0018] According to a second aspect, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt, comprising steps (A) and (B):

(A) subjecting nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide, nicotinamide-

2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride, nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside iodide, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside trifluoromethanesulfonate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside fluorosulfonate or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside perchlorate to salt metathesis comprising counter-ion exchange to afford a nicotinamide-2, 3, 5-tri- O-acyl-p-D-ribofuranoside salt;

(B) deacylating the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt to afford the nicotinamide-p-D-ribofuranoside salt.

[0019] The nicotinamide-p-D-ribofuranoside salt to be made by the method is not a bromide, a iodide, a triflate, a nonaflate, a fluorosufonate or a perchlorate.

[0020] According to a third aspect, the invention relates to a method of making a nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt from nicotinamide-2, 3, 5-tri-O-acyl-p- D-ribofuranoside bromide, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside iodide, nicotinamide-2, 3, 5-tri-O-acyl-p- D-ribofuranoside trifluoromethanesulfonate, nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside nonafluorobutanesulfonate nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside fluorosulfonate or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside perchlorate, comprising step (A):

(A) subjecting nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide, nicotinamide- 2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride, nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside iodide, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside trifluoromethanesulfonate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside fluorosulfonate or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside perchlorate to salt metathesis comprising counter-ion exchange to afford the nicotinamide-2, 3,5- tri-O-acyl-p-D-ribofuranoside salt.

[0021 ] The nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt to be made by the method is not a bromide, a iodide, a triflate, a nonaflate, a fluorosulfonate or a perchlorate.

[0022] According to a fourth aspect, the invention relates to crystalline nicotinamide-b- D-ribofuranoside D-, L- or DL-hydrogen malate; or crystalline nicotinamide-p-D- ribofuranoside D-, L- or DL-hydrogen tartrate; being characterized by a powder X-ray diffraction pattern, respectively.

[0023] Nicotinamide-B-D-ribofuranoside salts prepared according to the methods of the invention are frequently obtained in amorphous form and have to be subsequently crystallized, if desired, and if possible at all.

[0024] However, the addressed D-, L- or DL-hydrogen malates and D-, L- or DL- hydrogen tartrates surprisingly may be obtained directly via salt metathesis in crystalline form in high purity and excellent yield. This is extraordinarily advantageous e.g. in view of application and further processing. Therefore, it is suggested to use these salts in or as a nutritional supplement. Furthermore, said salts may serve as starting material for making further nicotinamide-B-D-ribofuranoside salts or related compounds.

[0025] According to a fifth aspect, the invention relates to a nutritional supplement comprising a nicotinamide-p-D-ribofuranoside salt obtained according to a method as defined in the first or second aspect or comprising a nicotinamide-p-D-ribofuranoside salt as defined in the fourth aspect.

[0026] According to a sixth aspect, the invention relates to a pharmaceutical composition comprising a nicotinamide-p-D-ribofuranoside salt obtained according to a method as defined in the first or second aspect or comprising a nicotinamide-p-D- ribofuranoside salt as defined in the fourth aspect.

[0027] According to a seventh aspect, the invention relates to a method of performing a chemical synthesis, comprising step (A): (A) providing a nicotinamide-p-D-ribofuranoside salt obtained by the method as defined in the first or second aspect, or providing a compound defined in the fourth aspect.

[0028] According to an eighth aspect, the invention relates to a method of making nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside triflate or iodide, the method comprising step (A):

(A) reacting tetra-O-acyl-p-D-ribofuranose of formula

wherein each R is independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CMO alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: Ci-e alkyl, Ci-e alkoxy, Ci-e thioalkyl, halogen, nitro, cyano, NH(Ci-e alkyl), N(Ci-e alkyl) ₂ , and S02N(Ci-6 alkyl) ₂ , with nicotinamide of formula

in presence of 0.9 to 1.5 mole equivalent trimethylsilyl triflate or iodide related to one mole of tetra-O-acyl-p-D-ribofuranose.

[0029] In a ninth aspect, the invention relates to a compound selected from nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-p-D-ribofuranoside nonafluorobutanesulfonate, nicotinamide-2, 3, 5-tri-O- acyl-p-D-ribofuranoside perchlorate, and nicotinamide-p-D-ribofuranoside perchlorate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside iodide, nicotinamide-p-D-ribofuranoside iodide, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside fluorosulfonate, and nicotinamide-p-D-ribofuranoside fluorosulfonate. BRIEF DESCRIPTION OF THE FIGURES

[0030] The present invention is further described by the appended figures, in which:

Fig. 1 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside D- hydrogen malate;

Fig. 2 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside L- hydrogen malate;

Fig. 3 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside

DL-hydrogen malate;

Fig. 4 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside D- hydrogen tartrate monohydrate;

Fig. 5 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside L- hydrogen tartrate;

Fig. 6 shows a powder X-ray pattern of crystalline nicotinamide-p-D-ribofuranoside

DL-hydrogen tartrate;

Fig. 7 shows a powder X-ray pattern of crystalline nicotinamide-2, 3, 5-O-triacetyl-p-D- ribofuranoside L-hydrogen tartrate;

Fig. 8 shows a powder X-ray pattern of crystalline nicotinamide-2, 3, 5-O-triacetyl-p-D- ribofuranoside D-hydrogen tartrate;

Fig. 9 shows a powder X-ray pattern of crystalline anhydrous nicotinamide-p-D- ribofuranoside D-hydrogen tartrate;

{x-axis: Position [°2Theta] (Copper(Cu); y-axis: Counts), respectively}.

DETAILED DESCRIPTION OF THE INVENTION

[0031 ] The various aspects of the present invention will now be described in more detail with reference to the figures.

First, second and third aspect: Methods according to the invention [0032] According to a first aspect, the invention relates to a method of replacing the anion X = Br, Cl , I , CF3SO3 (triflate), n-C ₄ F ₉ S0 ₃ (nonaflate), FS03 or CIO4 in a compound of formula

by an anion Y via salt metathesis comprising counter-ion exchange.

[0033] Accordingly, in the first aspect, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt, comprising step (A):

(A) subjecting nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate to salt metathesis comprising counter-ion exchange to afford the nicotinamide-p-D-ribofuranoside salt.

[0034] In an alternative embodiment, according to a second aspect, a nicotinamide- 2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate of formula

is subjected to salt metathesis in order to exchange Br, Cl , G, CF ₃ SO ₃ , n-C ₄ F ₉ S0 ₃ FSO ₃ or CIO ₄ through an anion V. Subsequently, the acyl groups are cleaved in order to afford the desired nicotinamide-p-D-ribofuranoside salt. [0035] Accordingly, in the second aspect, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt, comprising steps (A) and (B):

(A) subjecting nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate to salt metathesis comprising counter-ion exchange to afford a nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside salt; and

(B) deacylating the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt to afford the nicotinamide-p-D-ribofuranoside salt.

[0036] If desired, the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt obtained in step (A) may be used for purposes different from step (B).

[0037] Accordingly, in a third aspect, the invention relates to a method of making a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt, comprising step (A):

(A) subjecting a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate to salt metathesis comprising counter-ion exchange to afford the nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside salt.

[0038] Nicotinamide-p-D-ribofuranoside bromide [N1 -(p-D-Ribofuranosyl)-3- aminocarbonylpyridinium bromide)

as used in step (A) of the method defined in the first aspect is a well-known compound (CAS no 78687-39-5). E.g., Lee et al. disclose a chemical synthesis method thereof (Chem. Commun., 1999, 729-730). A further synthesis method is disclosed in EP 18173208.2 not yet published at the filing date of this application.

[0039] Said references also disclose the preparation of nicotinamide-2, 3, 5-tri-O-acyl- b-D-ribofuranoside bromide as a precursor of nicotinamide-p-D-ribofuranoside bromide. [0040] Nicotinamide-p-D-ribofuranoside triflate [N 1 -(p-D-Ribofuranosyl)-3- aminocarbonylpyridinium triflate]

is also a well-known compound (CAS no 445489-49-6).

[0041 ] Nicotinamide-p-D-ribofuranoside triflate and nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside triflate may be prepared e.g. by reacting nicotinamide with a tetra-O-acyl- p-D-ribofuranose in acetonitrile in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) to afford a nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside triflate. The acyl groups may then be cleaved according to known methods to afford the nicotinamide-p-D- ribofuranoside triflate (e.g. Makarova et al. :“Syntheses and chemical properties of b- nicotinamide riboside and its analogues and derivatives”, Beilstein J Org Chem 2019, 15: 401 -430; Tanimori et al., “An Efficient Chemical Synthesis of Nicotinamide Riboside (NAR) and Analogues”, Bioorganic & Medicinal Chemistry Letters 12 (2002) 1 135 - 1 137).

[0042] Nicotinamide-p-D-ribofuranoside nonaflate and nicotinamide-2, 3, 5-tri-O-acyl-p- D-ribofuranoside nonaflate, respectively nicotinamide-p-D-ribofuranoside perchlorate and nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside perchlorate, may be prepared by reacting nicotinamide with a tetra-O-acyl-p-D-ribofuranose in a solvent such as acetonitrile in the presence of trimethylsilyl nonafluorobutanesulfonate (CAS no 68734- 62-3), respectively trimethylsilyl perchlorate (CAS no 18204-79-0) to afford a nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside nonaflate, respectively perchlorate. The acyl groups may then be cleaved according to known methods to afford the nicotinamide-p-D-ribofuranoside nonaflate, respectively perchlorate.

[0043] Nicotinamide-p-D-ribofuranoside chloride and nicotinamide-2, 3, 5-tri-O-acyl-p- D-ribofuranoside chloride, nicotinamide-p-D-ribofuranoside iodide and nicotinamide- 2, 3, 5-tri-O-acyl-p-D-ribofuranoside iodide, respectively nicotinamide-p-D-ribofuranoside fluorosulfonate and nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside sulfonate, may be prepared by reacting nicotinamide with a tetra-O-acyl-p-D-ribofuranose in a solvent such as acetonitrile in the presence of trimethylsilyl choride (CAS no 75-77-4), trimethylsilyl iodide (CAS no. 16029-98-4), respectively trimethylsilyl fluorosulfonate (CAS no 3167- 56-4) to afford a nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride, iodide, respectively fluorosulfonate. The acyl groups may then be cleaved according to known methods to afford the nicotinamide-p-D-ribofuranoside chloride, iodide, respectively fluorosulfonate.

[0044] The term“salt metathesis” as used in this disclosure is synonymously used with terms such as“double replacement reaction”, “double displacement reaction" or “double decomposition reaction”. Salt metathesis for exchanging counter-ions between two different salts is a known technique.

[0045] Thus, step (A) defines a reaction, wherein a first salt, e.g. a nicotinamide-p-D- ribofuranoside salt NR ⁺ Br (or a nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt AcONR ⁺ Br) is subjected to a salt metathesis using a suitable second salt comprising a cation Cat ⁺ and an anion V to afford a nicotinamide-p-D-ribofuranoside salt NR ⁺ Y (or AcONR ⁺ Y ) and Cat ⁺ Br via counter-ion exchange, i.e. exchange of Br in NR ⁺ Br (or AcONR ⁺ Br) by Y . This reaction is summarized by the following equation:

[0046] NR ⁺ Br (or AcONR ⁺ Br ) + Cat ⁺ Y ® NR ⁺ Y (or AcONR ⁺ Y ) + Cat ⁺ Br

[0047] The driving force of a salt metathesis reaction such as in the above equation may be the formation of more stable salts as well as the removal of a product from the chemical equilibrium of the reaction, e.g. by precipitation of one of the formed NR ⁺ Y (AcONR ⁺ Y ) or Cat ⁺ Br . Thus, in order to drive the reaction to the products, the educts have to be selected in view of solubility in one another or in a solvent, respectively in view of favorable energies.

[0048] An analogous mechanism applies to the reaction of the chloride, iodide, triflate, nonaflate, fluorosulfonate and perchlorate. [0049] If the salt metathesis reaction is performed in a solvent, the influence of same on the reaction will be explained in more detail hereinunder in the respective section Solvent.

[0050] The term“salt metathesis” as used herein does not mean that the anion of the b-nicotinamide riboside is exchanged by another anion by means of ion exchange using an ion exchanger. Thus, the method defined in step (A) excludes an anion exchange by means of an ion exchanger.

[0051 ] However, the method does not exclude that in any reaction step prior to step (A) or subsequently to step (A) an ion exchanger may be used.

[0052] Nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside bromides, nicotinamide-2, 3,5- tri-O-acyl- -D-ribofuranoside chlorides, nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside iodides, nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside trifluoromethanesulfonates, nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside nonafluorobutanesulfonates, nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside fluorosulfonates or nicotinamide-2, 3,5- tri-O-acyl- -D-ribofuranoside perchlorates as used in step (B) of the method according to the second aspect are either known or can be prepared according to known methods.

[0053] The term“acyl” as used in connection with nicotinamide-2, 3, 5-tri-0-acyl-p-D- ribofuranoside salts, i.e. the bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate, means that acyl is independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CMO alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: Ci-e alkyl, Ci-e alkoxy, Ci-e thioalkyl, halogen, nitro, cyano, NH(Ci-e alkyl), N(Ci-e alkyl) ₂ , and S02N(Ci-6 alkyl) ₂ .

[0054] In one embodiment, the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt obtained in step (A) may be isolated and purified before it is deacylated in step (B).

[0055] In another embodiment, the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside salt is not purified prior to deacylation in step (B).

[0056] Deacylation (deprotection) according to step (B) may be performed according to methods known in the art, e.g. by subjecting the salt obtained in step (A) to an acid such as hydrogen bromide, hydrogen chloride, hydrogen iodide or sulfuric acid, or to a base such as ammonia.

Preferred embodiments according to the first, second and third aspect: Nicotinamide-3- D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-tri-0-acyl-3-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate used in step (A) as starting materials

[0057] According to the invention, the nicotinamide-p-D-ribofuranoside salt or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt used in step (A) is the bromide, the chloride, the iodide, the triflate, the nonaflate, the fluorosulfonate or the perchlorate. The bromides and triflates are well amenable compounds and have therefore been used in the art as starting material for numerous subsequent process steps.

[0058] Furthermore, at least nicotinamide-p-D-ribofuranoside bromide or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide or nicotinamide-p-D- ribofuranoside chloride or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride may be provided in crystalline form which is favorable due to the purity thereof in view of making further crystalline nicotinamide-p-D-ribofuranoside salts.

[0059] In a preferred embodiment, a method of making a nicotinamide-p-D- ribofuranoside bromide or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide is used as disclosed in EP 18173208.2 (not yet published at the filing date of this application). This reference is incorporated herein in its entirety.

[0060] Accordingly, in one embodiment of the first aspect, the method according to the invention comprises prior to step (A) steps (X) and (Y) and step (Z):

(X) subjecting a tetra-O-acyl-p-D-ribofuranose of formula

to hydrogen bromide in acetic acid to afford a tri-O-acyl-D-ribofuranoside bromide (in the form of a mixture of the b- and the a-anomer) of formula

(Y) reacting the tri-O-acyl-D-ribofuranoside bromide with nicotinamide

to afford a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide of formula

(Z) deacylating the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside obtained in step (Y) by removing the R groups using hydrogen bromide in acetic acid to afford the nicotinamide-p-D-ribofuranoside bromide compound of formula

wherein the nicotinamide-p-D-ribofuranoside bromide obtained in step (Z) is used in step (A).

[0061 ] Basically, in other embodiments, acids different from HBr in acetic acid or bases such as ammonia may be used in the deacylation step (Z).

[0062] Nicotinamide-2, 3, 5-tri-0-acyl-B-D-ribofuranoside bromide obtained in step (Y) is typically obtained in mixture with the a-anomer. E.g., the molar ratio b:a may be about 85:15.

[0063] Accordingly, in one embodiment, if not purified at the stage of the mixture of b- and a-anomers, in subsequent steps, the educt is also provided as a mixture of b- and a- anomers. Purification may lead to the pure b-anomers.

[0064] In another embodiment, nicotinamide-2, 3, 5-tri-0-acyl^-D-ribofuranoside bromide may be purified in order to result in the pure b-anomer before it is subjected to cleavage of the acyl groups.

[0065] According to another embodiment of the first aspect, the invention relates to a method comprising prior to step (A) steps (X) and (Y):

(X) subjecting a tetra-O-acyl-p-D-ribofuranose of formula

wherein each R is independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CMO alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: Ci-e alkyl, Ci-e alkoxy, Ci-e thioalkyl, halogen, nitro, cyano, NH(CI-6 alkyl), N(Ci-e alkyl) ₂ , and S02N(Ci-6 alkyl) ₂ , in the presence of trimethylsilyl chloride, trimethylsilyl bromide, trimethylsilyl iodide, trimethylsilyl triflate, trimethylsilyl nonaflate, trimethylsilyl fluorosulfonate or trimethylsilyl perchlorate to nicotinamide

to afford the respective nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate, fluorosulfonate or perchlorate of formula

(Y) deacylating the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate or perchlorate obtained in step (X) by removing the R groups to afford the nicotinamide-p-D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate, fluorosulfonate or perchlorate compound of formula

wherein nicotinamide-p-D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate, fluorosulfonate or perchlorate formed in step (Y) is used in step (A).

[0066] In one embodiment of the second aspect, the method according to the invention comprises prior to step (A) steps (X) and (Y):

(X) subjecting a tetra-O-acyl-p-D-ribofuranose of formula

to hydrogen bromide in acetic acid to afford a tri-O-acyl-D-ribofuranoside bromide (in the form of a mixture of the b- and the a-anomer) of formula

(Y) reacting the tri-O-acyl-D-ribofuranoside bromide with nicotinamide

to afford a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide of formula wherein the nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide obtained in step (Y) is used in step (A).

[0067] The product obtained in step (Y) may also be employed in the method defined in the third aspect.

[0068] R is an acyl group independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CMO alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: Ci-e alkyl, Ci-e alkoxy, Ci-e thioalkyl, halogen, nitro, cyano, NH(CI-6 alkyl), N(Ci- ₆ alkyl) ₂ , and S0 ₂ N(Ci- ₆ alkyl) ₂ .

[0069] The term “acyl” as synonymously used with the term “acyl group” in nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside bromide means that the acyl group may be independently selected from alkyl carbonyl, aryl carbonyl or heteroaryl carbonyl.

[0070] The term“alkyl carbonyl” is synonymously used with the term“alkanoyl”.

[0071 ] In one embodiment, R is independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CMO alkyl carbonyl and benzoyl, and is preferably acetyl.

[0072] In one embodiment, acyl may be substituted.

[0073] In one embodiment, acyl may be independently substituted with one or more of the following substituents: Ci-e alkyl, Ci-e alkoxy, Ci-e thioalkyl, halogen, nitro, cyano, NH(C _{I -6} alkyl), N(C _{I -6} alkyl) ₂ , and S0 ₂ N(Ci- ₆ alkyl) ₂ . [0074] In one embodiment, acyl is Ci-e alkanoyl such as formyl, acetyl, propionyl, butyryl, valeryl or cyclohexyl, optionally substituted with one or more of the substituents mentioned above.

[0075] In another embodiment, acyl is benzoyl or naphthoyl, preferably benzoyl, optionally substituted with one or more of the substituents mentioned above.

[0076] Tetra-O-acyl^-D-ribofuranoses are either known compounds or may be prepared according to known methods.

[0077] In a preferred embodiment, commercially available tetra-O-acetyl^-D- ribofuranose (CAS Number 13035-61 -5)

is used in step (X) to afford 2,3,5-tri-O-acyl-D-ribofuranoside bromide.

[0078] Nicotinamide-2, 3, 5-tri-0-acyl- -D-ribofuranoside bromide obtained in step (Y) is typically produced as a mixture of anomers such as a mixture of anomers b and a, such as b:a in a ratio of from about 5:1 to 6: 1.

[0079] In one embodiment, the crude nicotinamide-2, 3, 5-tri-0-acyl^-D-ribofuranoside bromide can be employed in step (A) of the method according to the second aspect, i.e. it may be subjected to salt metathesis. Subsequently the formed salt is deacylated according to step (B) to afford the desired nicotinamide-B-D-ribofuranoside salt.

[0080] In another embodiment, the crude nicotinamide-2, 3, 5-tri-0-acyl^-D- ribofuranoside bromide may be employed in step (Z) resulting in nicotinamide-B-D- ribofuranoside bromide via deacylation. Nicotinamide-B-D-ribofuranoside bromide may then be used in step (A) of the method according to the first aspect to afford the desired nicotinamide-B-D-ribofuranoside salt via salt metathesis. [0081 ] In still another embodiment, it may be advantageous to purify and crystallize the crude nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide obtained in step (Y) prior to step (Z). Using a purified and crystallized nicotinamide-2, 3, 5-tri-0-acyl-p-D- ribofuranoside bromide in the deacylation (deprotecting) step according to step (Z) may improve the tendency of nicotinamide-p-D-ribofuranoside bromide to result in a crystallized and thus in a substantially pure form.

[0082] Preferably, nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide obtained in step (Y) may be re-crystallized from acetone. The pure b-anomer is obtained.

[0083] Accordingly, in one embodiment, the method further comprises step (Y1 ):

(Y1 ) purifying the product obtained in step (Y).

[0084] Preferably, purification according to step (Y1) is crystallization or re crystallization.

[0085] The yield over steps (X), (Y) and (Y1) is typically in the range of from 40 to 50 %.

[0086] In one embodiment, the purified nicotinamide-2, 3, 5-tri-0-acyl-p-D- ribofuranoside bromide may be used in step (A) as defined in the second aspect, i.e. it may be subjected to salt metathesis. Subsequently the formed salt is deacylated according to step (B) to afford the desired nicotinamide-B-D-ribofuranoside salt.

[0087] In another embodiment, the purified nicotinamide-2, 3, 5-tri-0-acyl-p-D- ribofuranoside bromide may be deacylated resulting in nicotinamide-B-D-ribofuranoside bromide which may be used in step (A) of the method according to the first aspect to afford the desired nicotinamide-B-D-ribofuranoside salt via salt metathesis.

[0088] If step (A) as defined in the first aspect is to be carried out, the acyl groups in nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide obtained in step (Y) or (Y1 ) have to be cleaved, i.e. the protected hydroxyl groups are deprotected.

[0089] Basically any method known in the art may be used to remove the acyl groups from the protected OH-groups. Cleavage may be advantageously performed with hydrogen bromide in acetic acid. [0090] This reaction may be beneficially carried out also at a large scale.

[0091 ] Nicotinamide-p-D-ribofuranoside bromide frequently directly precipitates from the solution obtained in the deprotection step in the form of crystals.

[0092] Crystallized nicotinamide-p-D-ribofuranoside bromide may be obtained in a purity of more than 97 %, i.e. nearly free from the a-anomer, and containing only minor amounts of nicotinamide which has been used for substituting bromide in tri-O-acyl-p-D- ribofuranoside bromide, respectively for neutralizing an excess of hydrogen bromide.

[0093] If further necessary, nicotinamide-p-D-ribofuranoside bromide may be further purified, preferably by re-crystallization. A suitable solvent is e.g. methanol.

[0094] In a preferred embodiment, the method further comprises step (Z1 ):

(Z1 ) purifying the product obtained in step (Z).

[0095] In a preferred embodiment, purification according to step (Z1 ) comprises or is crystallization or re-crystallization.

[0096] The yield over steps (Z) and (Z1 ) is typically in the range of from 60 to 70 %.

[0097] Advantageously, other salts, preferably crystalline salts, in which the anion preferably is a pharmaceutically acceptable anion, may be prepared starting from the bromide or triflate via salt metathesis according to the methods of the invention.

[0098] Preferably, nicotinamide-p-D-ribofuranoside hydrogen malates and nicotinamide-p-D-ribofuranoside hydrogen tartrates, preferably in crystalline form, may be synthesized as well as the 2,3,5-O-triacyl compounds thereof.

[0099] In another embodiment of the second aspect, the invention relates to a method comprising prior to step (A) steps (X):

(X) subjecting a tetra-O-acyl-p-D-ribofuranose of formula wherein each R is independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from C1-10 alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: C1-6 alkyl, Ci-e alkoxy, C1-6 thioalkyl, halogen, nitro, cyano, NH(Ci-e alkyl), N(Ci-e alkyl) ₂ , and S02N(Ci-6 alkyl) ₂ , in the presence of trimethylsilyl chloride, trimethylsilyl bromide, trimethylsilyl iodide, trimethylsilyl triflate, trimethylsilyl nonaflate, trimethylsilyl fluorosulfonate or trimethylsilyl perchlorate to nicotinamide

to afford a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate, fluorosulfonate or perchlorate of formula

wherein nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside chloride, bromide, iodide, triflate, nonaflate, fluorosulfonate or perchlorate formed in step (X) is used in step (A).

Pharmaceutically acceptable ions [00100] Preferably, the counter-ion V of the salt obtained in step (A) via counter-ion exchange originating from salt Cat ⁺ Y is a pharmaceutically acceptable ion.

[00101 ] The term“pharmaceutically acceptable ion” as used herein encompasses ions selected from the group consisting of inorganic ions; or carboxylates, wherein the carboxylic acid from which the carboxylate is derived, is optionally substituted with one or more substituents independently selected from the group consisting of carboxyl, hydroxyl, thio, keto, amino, mono Ci-e alkyl, hydroxy Ci-e alkylene and di(Ci-e alkyl) amino; or

C1-12 alkyl sulfonates; or arylsulfonates, wherein the aryl moiety is optionally substituted with one or more substituents independently selected from the group consisting of carboxyl, hydroxyl, amino, mono Ci-e alkyl and di(Ci-e alkyl) amino, halogen, Ci-e alkyl; and wherein the pharmaceutically acceptable salt is not a bromide or a iodide or a triflate or a nonaflate or a fluorosulonate or a perchlorate.

[00102] In a preferred embodiment, the inorganic ion is selected from the group consisting of chloride, hydrogen sulfate, sulfate, dihydrogen phosphate, monohydrogen phosphate, phosphate, nitrate, hydrogen carbonate and carbonate; carboxylate is selected from the group consisting of formate, acetate, oxalate, malonate, succinate, fumarate, maleate, citrate, malate, tartrate, ascorbate, glucuronate, a- ketoglutarate, benzoate and salicylate;

Ci-i2 alkylsulfonate is selected from the group consisting of mesylate and camsylate; arylsulfonate is selected from the group consisting of besylate and tosylate,

[00103] In a preferred embodiment, the pharmaceutically acceptable ion is the malate. [00104] In a particularly preferred embodiment, the pharmaceutically acceptable ion is the hydrogen malate.

[00105] The term“hydrogen malate” means the monocarboxylate.

[00106] In a further particularly preferred embodiment, the hydrogen malate is the D-, L- or DL-stereoisomer.

[00107] In a further preferred embodiment, the pharmaceutically acceptable anion is the tartrate.

[00108] In a particularly preferred embodiment, the pharmaceutically acceptable anion is the hydrogen tartrate.

[00109] The term“hydrogen tartrate” means the monocarboxylate

[001 10] In a further particularly preferred embodiment, the hydrogen tartrate ion is the D-, L- or DL-stereoisomer.

[001 1 1 ] The preparation of D-, L- or DL-stereoisomers of hydrogen malate or hydrogen tartrate is particularly preferred since the method according to the invention provides these compounds in a high yield and in a crystallinity which is particularly advantageous in view of the handling and further processing of the salt.

[001 12] Typically, crystalline compounds are already obtained directly in the salt metathesis reaction.

[001 13] This is advantageous compared to e.g. a counter-ion exchange via ion- exchanger where the compounds typically are obtained in an amorphous form and have to be crystallized in a subsequent step.

Cation Cat ⁺ related to the pharmaceutically acceptable ion Y ^~ to be subjected to salt metathesis with nicotinamide-3-D-hbofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-tri-0-acyl-3-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate

[001 14] Nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate can be subjected to salt metathesis using basically any salt having a pharmaceutically acceptable anion.

[001 15] Although not limited, cation Cat ⁺ as used in connection with the pharmaceutically acceptable anion preferably originates from an ammonium salt or a phosphonium salt.

[001 16] Preferably, in one embodiment, the cation of the salt is [NR ¹ R ² R ³ R ⁴ ] ⁺ , wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from H, C1-12 alkyl and aryl, optionally substituted.

[001 17] In one embodiment, the cation of the salt is NH ⁺ .

[001 18] In a preferred embodiment, the cation of the salt originates from a primary ammonium salt, i.e. the cation of the salt is [NR ¹ H ₃ ] ⁺ , wherein R ¹ is selected from C1-12 alkyl and aryl, optionally substituted.

[001 19] In another preferred embodiment, the cation of the salt originates from a secondary ammonium salt, i.e. the cation of the salt is [NR ¹ R ² H ₂ ] ⁺ , wherein R ¹ and R ² are independently selected from C1-12 alkyl and aryl, optionally substituted.

[00120] In a further preferred embodiment, one of R ¹ , R ² , R ³ and R ⁴ in [NR ¹ R ² R ³ R ⁴ ] ⁺ is H. Accordingly, the cation of the salt originates from a tertiary ammonium salt, i.e. the cation of the salt is [NR ¹ R ² R ³ H] ⁺ , wherein R ¹ , R ² and R ³ are independently selected from C1-12 alkyl and aryl, optionally substituted.

[00121 ] In still another preferred embodiment, the cation is a quaternary ammonium salt. Accordingly, the cation of the salt is [NR ¹ R ² R ³ R ⁴ ] ⁺ , wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from C1-12 alkyl and aryl, optionally substituted.

[00122] In a preferred embodiment, [NR ¹ R ² R ³ R ⁴ ] ⁺ is [N(C ₂ H5)4] ⁺ or [N(C ₄ H9)4] ⁺ .

[00123] In a further preferred embodiment, one of R ¹ , R ² , R ³ and R ⁴ is benzyl. [00124] In another embodiment, the cation of the salt originates from a N-heterocyclic aromatic system or an N-alkylated heterocyclic aromatic system such as pyridine or n- methyl pyridine.

[00125] In another embodiment, the cation of the salt is [PR ¹ R ² R ³ R ⁴ ] ⁺ , wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from H, C1-12 alkyl and aryl, optionally substituted.

[00126] In a further preferred embodiment, one of R ¹ , R ² , R ³ and R ⁴ in [PR ¹ R ² R ³ R ⁴ ] ⁺ is H.

[00127] The use of lithium salts or sodium salts comprising a pharmaceutically acceptable anion in the salt metathesis reaction according to the invention is conceivable, too.

[00128] Suitable salts are commercially available or may be prepared according to known methods, e.g. by reacting triethylamine or tributylamine or tetraethylammonium hydroxide or tetrabutylammonium hydroxide or benzyltrimethyl ammonium hydroxide with an acid such as sulfuric acid or a carboxylic acid such as malic acid or tartraric acid in molar ratios that allow for the preparation of monovalent or divalent anions.

Solvent

[00129] The salt metathesis may be performed without a solvent, i.e. via salt metathesis of a solid nicotinamide-p-D-ribofuranoside salt or solid nicotinamide-2, 3, 5-tri- O-acyl-p-D-ribofuranoside salt with e.g. a liquid salt.

[00130] In a preferred embodiment, the salt metathesis in step (A) is performed in presence of a solvent.

[00131 ] The following non-limiting embodiments I, II, III or IV for performing the above- defined salt metathesis reaction are preferred:

[00132] Embodiment I: The solvent is selected such that NR ⁺ Br (or AcONR ⁺ Br ) and Cat ⁺ Y are both soluble in said solvent, however NR ⁺ Y (or AcONR ⁺ Y ) obtained in step (A) is not soluble in said solvent and precipitates, whereas Cat ⁺ Br is soluble. NR ⁺ Y (or AcONR ⁺ Y ) may then be isolated by filtration. [00133] Embodiment II: The solvent is selected such that NR ⁺ Br (or AcONR ⁺ Br ) and Cat ⁺ Y are both soluble in said solvent, however NR ⁺ Y (or AcONR ⁺ Y ) obtained in step (A) is soluble in said solvent, whereas Cat ⁺ Br is not soluble and precipitates. NR ⁺ Y (or AcONR ⁺ Y ) may e.g. then be isolated from the supernatant according to known techniques.

[00134] Embodiment III: The solvent is selected such that NR ⁺ Br and NR ⁺ Y (or AcONR ⁺ Br and AcONR ⁺ Y ) obtained in step (A) are not soluble in said solvent, whereas both Cat ⁺ Br and Cat ⁺ Y are soluble. NR ⁺ Y (or AcONR ⁺ Y ) may e.g. then be isolated by filtration.

[00135] Embodiment IV: The solvent is selected such that NR ⁺ Br and NR ⁺ Y (or AcONR ⁺ Br and AcONR ⁺ Y ) obtained in step (A) are soluble in said solvent, whereas Cat ⁺ Y and Cat ⁺ Br are not soluble. NR ⁺ Y (or AcONR ⁺ Y ) may e.g. then be isolated from the supernatant according to known techniques.

[00136] Instead of NR ⁺ Br and AcONR ⁺ Br also NR ⁺ CI and AcONR ⁺ Cr· NR ⁺ I and AcONR ⁺ r, NR ⁺ CF ₃ S0 ₃ ^· and Ac0NR ⁺ CF ₃ S0 ₃ or NR ⁺ n-C ₄ F ₉ S0 ₃ - and Ac0NR ⁺ n-C ₄ F ₉ S0 ₃ ^· , NR ⁺ FS0 ₃ and AcONR ⁺ FS0 ₃ or NR ⁺ CI0 ₄ and AcONR ⁺ CI0 ₄ may be used in embodiments I to IV.

[00137] Accordingly, by appropriate choice of the solvent used in the salt metathesis reaction defined in step (A), i.e. by determining a solubility chart, the result of the salt metathesis reaction can be predicted. The person skilled in the art may be expected to determine such solubility chart by routine experimentation.

[00138] Embodiment I provides for good results provided Cat ⁺ Y is an ammonium salt or phosphonium salt as defined above, preferably an ammonium salt.

[00139] In a further preferred embodiment, Embodiment I provides for good results provided an alcohol is used as solvent, or the solvent comprises an alcohol, and Cat ⁺ Y preferably is an ammonium salt or phosphonium salt as defined above, preferably an ammonium salt. [00140] Preferably, the alcohol used for salt metathesis is selected from the group consisting of methanol, ethanol, a propanol or a butanol, or a mixture of two or more thereof, optionally the alcohol or the mixture comprising water.

[00141 ] The inventors of the present invention discovered that unexpectedly the formed nicotinamide-B-D-ribofuranoside and nicotinamide-triacyl-O-B-D-ribofuranoside salts provide for unusual high solubility differences compared to the nicotinamide-B-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate, respectively nicotinamide-tri-O-acyl-B-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate used for salt metathesis in the specified alcohol such that under the reaction conditions in particular embodiment I is the method of choice.

[00142] Preferably, in step (A) a saturated solution of the nicotinamide-p-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate in one or more of the alcohols defined above, optionally comprising water, and a suitable ammonium salt or phosphonium salt are combined with one another, wherein step (A) takes place, i.e. the nicotinamide-p-D- ribofuranoside salt or the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt generated by counter-ion exchange precipitates and can be isolated by filtration.

[00143] The term “saturated solution” means in a preferred embodiment that concentrated solutions of NR ⁺ Br (or AcONR ⁺ Br) and Cat ⁺ Y are prepared such that the solubility limit at 23 °C is not exceeded.

[00144] The term “saturated solution” means in another preferred embodiment that concentrated solutions of NR ⁺ Br , NR ⁺ Cr, NR ⁺ r, NR ⁺ CF ₃ S0 ₃ ^· , NR ⁺ n-C ₄ F ₉ S0 ₃ -, NR ⁺ FSOY or NR ⁺ CI0 ₄ ^· (or AcONR ⁺ Br , AcONR ⁺ Cr, AcONR ⁺ r, Ac0NR ⁺ CF ₃ S0 ₃ , Ac0NR ⁺ n-C ₄ F ₉ S0 ₃ , ACONR ⁺ FS0 ₃ or ACONR ⁺ CI0 ₄ ) and Cat ⁺ Y are prepared such that the solubility limit at 23 °C is not exceeded.

[00145] Preferably, the salt metathesis reaction according to step (A) is performed at ambient temperature, i.e. in the range of from 5 to 60 °C, preferably 10 to 40 °C. [00146] It is evident that the salt metathesis reaction defined in step (A) is not restricted to the ammonium salts or phosphonium salts and the alcohol defined above.

[00147] In a preferred embodiment, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt or a nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside salt, wherein step (A) as defined in the first and the second aspect comprises at least steps (A1 ) and (A2):

(A1 ) reacting NH ₃ or NR ¹ H ₂ or NR ¹ R ² H or NR ¹ R ² R ³ or [NR ¹ R ² R ³ R ⁴ ]OH with an acid preferably comprising a pharmaceutically acceptable anion to afford the respective ammonium salt, wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from C1-12 alkyl and aryl, optionally substituted.

(A2) reacting nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate with the ammonium salt from step (A1 ) to perform salt metathesis comprising counter-ion exchange to afford the nicotinamide-p-D-ribofuranoside salt or the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt, wherein acyl has the meaning as defined above.

[00148] In a preferred embodiment, NR ¹ R ² R ³ or [NR ¹ R ² R ³ R ⁴ ]OH is used in step (A1 ).

[00149] Likewise, in another embodiment, the invention relates to a method of making a nicotinamide-p-D-ribofuranoside salt or a nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside salt, the method comprising:

(A1 ) reacting PH ₃ or PR ¹ H ₂ or PR ¹ R ² H or PR ¹ R ² R ³ or [PR ¹ R ² R ³ R ⁴ ]OH with an acid to afford the respective phosphonium salt, wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from Ci-i ₂ alkyl and aryl, optionally substituted.

(A2) reacting nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-tri-O-acyl-p-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate with the phosphonium salt from step (A ₀ ) to perform salt metathesis comprising counter-ion exchange to afford the nicotinamide-p-D-ribofuranoside salt or the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt, wherein acyl has the meaning as defined above.

[00150] In a preferred embodiment, PR ¹ R ² R ³ or [PR ¹ R ² R ³ R ⁴ ]OH is used in step (A1 ). Further purification

[00151 ] If necessary, the product obtained in step (A) or step (B) may be purified according to known methods in order to obtain the pure b-anomer.

[00152] In one embodiment, the product may be recrystallized.

[00153] In another embodiment, the product may be dissolved in a suitable solvent and then precipitated by addition of a solvent, in which the product is not soluble.

[00154] Accordingly, the method as defined in the first, second or third aspect, further comprises step (C):

(C) purifying the salt obtained in step (A) or (B), preferably by crystallization.

[00155] In one embodiment, the method according to the invention may start in step (A) from pure b-anomers, i.e. pure nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or pure nicotinamide-2, 3,5-0- triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate.

[00156] The term“pure” means that nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or nicotinamide-2, 3, 5-O-triacyl-p- D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate may contain up to 5 % of the a-anomer.

[00157] In one embodiment, the salts are provided in isolated form, optionally purified, prior to their use in step (A).

[00158] In another embodiment, the method may start in step (A) from b-anomers containing more than 5 % of the a-anomer, i.e. non-purified nicotinamide-p-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate or non-purified nicotinamide-2, 3, 5-0-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate.

[00159] In one embodiment, the salts are provided in dissolved form as generated in the respective synthesis prior to their use in step (A), i.e. in non-purified form.

[00160] Summing up, the method according to the invention advantageously allows for the preparation of nicotinamide-p-D-ribofuranoside salts on various pathways, preferably pathways according to pathways (P1 ) to (P5), either starting from pure b-anomers or b- anomers containing the a-anomer:

[00161 ] Pathway (P1 ) comprises steps (a), (b), (g) and (d):

(a) cleaving the acyl groups in nicotinamide-2, 3, 5-0-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate containing up to 5 % of the a-anomer to afford the nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate;

(b) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate ;

(y) subjecting the nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate to salt metathesis to afford the nicotinamide-p-D-ribofuranoside salt;

(d) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside salt.

[00162] Pathway (P2) comprises steps (a), (b), (g) and (d):

(a) subjecting a nicotinamide-2, 3, 5-0-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate containing up to 5 % of the a-anomer to salt metathesis to afford a nicotinamide-2, 3, 5-O-triacyl b-D- ribofuranoside salt;

(b) isolating and optionally purifying the nicotinamide-2, 3, 5-O-triacyl-p-D- ribofuranoside; (g) cleaving the acyl groups in the nicotinamide-2, 3, 5-O-triacyl-p-D-ribofuranoside salt to afford a nicotinamide-p-D-ribofuranoside salt;

(d) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside salt.

[00163] Pathway (P3) comprises steps (a) and (p):

(a) cleaving the acyl groups in nicotinamide-2, 3, 5-O-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate containing up to 5 % of the a-anomer to afford the nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate and subjecting the formed nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate without prior isolation to salt metathesis to afford a nicotinamide-p-D-ribofuranoside salt;

(b) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside salt.

[00164] Pathway (P4) comprises steps (a), (p), (y) and (d):

(a) subjecting nicotinamide-2, 3, 5-O-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate containing more than 5 % of the a-anomer to salt metathesis to afford a nicotinamide-2, 3, 5-O-triacyl p-D- ribofuranoside salt;

(b) isolating and optionally purifying the nicotinamide-2, 3, 5-O-triacyl-p-D- ribofuranoside;

(g) cleaving the acyl groups in the nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside salt to afford a nicotinamide-p-D-ribofuranoside salt;

(d) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside salt.

[00165] Pathway (P5) comprises steps (a) and (p):

(a) cleaving the acyl groups in nicotinamide-2, 3, 5-O-triacyl-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate containing more than 5 % of the a-anomer to afford the nicotinamide-p-D- ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate and subjecting the formed nicotinamide-p-D-ribofuranoside bromide, chloride, iodide, triflate, nonaflate, fluorosulfonate or perchlorate without prior isolation to salt metathesis to afford a nicotinamide-p-D-ribofuranoside salt;

(b) isolating and optionally purifying the nicotinamide-p-D-ribofuranoside salt.

[00166] The term“without prior isolation” as used in pathways (P3) and (P5) denotes that the salt metathesis is carried out in situ.

[00167] Preferably, the salts carrying the pharmaceutically acceptable anion are also formed in situ, i.e. in the reaction mixture obtained in the cleaving step of the acyl groups.

[00168] In one embodiment, the various pathways are exemplarily shown in the following scheme starting from nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside bromide preparing the L-hydrogen tartrates:

[00169] Scheme 1 : Pathways P1 to P5 for making nicotinamide-B-D-ribofuranoside L- hydrogen tartrate starting from nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside bromide

[00170] In another embodiment, the various pathways P1 to P5 are exemplarily shown in Scheme 2 starting from nicotinamide-2, 3, 5-0-triacetyl-p-D-ribofuranoside triflate preparing the L-hydrogen tartrates (pathways P2 and P3 are not shown):

[00171 ] As already mentioned above, in one embodiment, cleavage of acyl groups in nicotinamide-2, 3, 5-tri-0-acyl-B-D-ribofuranoside salts may be performed under acidic conditions using sulfuric acid, hydrochloric acid or hydrobromic acid or hydroiodic acid The resulting acidic mixtures may be neutralized with ammonia or amines such as triethylamine or tributylamine, if necessary, prior to isolating the respective nicotinamide- b-D-ribofuranoside salts

[00172] In another embodiment, cleavage of acyl groups in nicotinamide-2, 3, 5-tri-O- acyl-B-D-ribofuranoside salts may be performed under basis conditions using ammonia or triethylamine or tributylamine prior to isolating the respective nicotinamide-B-D- ribofuranoside salts.

Fourth aspect: Crystalline nicotinamide-p-D-ribofuranoside hydrogen malates, nicotinamide-p-D-ribofuranoside hydrogen tartrates, nicotinamide-2, 3, 5-0- triacetyl-p-D-ribofuranoside malates, and nicotinamide-2, 3, 5-O-triacetyl-p-D- ribofuranoside tartrates

[00173] According to a fourth aspect, the invention relates to crystalline nicotinamide-b- D-ribofuranoside malates, nicotinamide-p-D-ribofuranoside tartrates, nicotinamide-2, 3,5- O-triacetyl-p-D-ribofuranoside malates, and nicotinamide-2, 3, 5-0-triacetyl-p-D- ribofuranoside tartrates.

[00174] In a preferred embodiment, the invention relates to crystalline nicotinamide-b- D-ribofuranoside hydrogen malates, nicotinamide-p-D-ribofuranoside hydrogen tartrates, nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside hydrogen malates, and nicotinamide- 2, 3, 5-O-triacetyl-p-D-ribofuranoside hydrogen tartrates.

[00175] In a particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen malate is nicotinamide-p-D-ribofuranoside D-hydrogen malate, which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 1 , below, ± 0.2 degrees two theta:

Table 1 Pos. [°2Th-l Height [cts] FWHM Left [°2Th-l d-spacmg \l] Rel. Int. \%\

11.8481 445.20 0.1535 7.46957 0.61

12.6145 22336.51 0.1663 7.01743 30.71

13.0454 990.49 0.1023 6.78661 1.36

13.6055 7710.12 0.1407 6.50845 10.60

14.8288 14677.80 0.1407 5.97418 20.18

15.3150 3657.25 0.1279 5.78560 5.03

16.6048 27830.00 0.1535 5.33898 38.27

16.8966 21052.43 0.1407 5.24745 28.95

17.4485 11645.88 0.1535 5.08269 16.01

17.7534 3843.61 0.1407 4.99606 5.29

19.1083 13443.46 0.1535 4.64476 18.49

19.8613 2277.97 0.1023 4.47034 3.13

20.8582 8387.39 0.1535 4.25887 11.53

22.4545 72723.85 0.1663 3.95960 100.00

22.9093 12085.33 0.1023 3.88200 16.62

23.0396 13135.67 0.1279 3.86035 18.06

24.1487 59629.80 0.1663 3.68550 81.99

24.9146 28316.42 0.1791 3.57392 38.94

25.2144 7756.64 0.1151 3.53210 10.67

25.9681 34260.16 0.1791 3.43127 47.11

26.6864 10373.63 0.1872 3.33776 14.26

26.7773 7203.21 0.0624 3.33490 9.90

27.2747 3052.68 0.0936 3.26708 4.20

27.5074 7926.64 0.1716 3.23997 10.90

27.8283 2567.70 0.1560 3.20334 3.53

28.4116 3658.38 0.1872 3.13888 5.03

28.8702 3091.52 0.2184 3.09006 4.25

29.6423 5092.55 0.1872 3.01130 7.00

30.3593 5978.38 0.2340 2.94180 8.22

30.7689 1776.07 0.1248 2.90356 2.44

31.0365 3671.22 0.1560 2.87914 5.05

31.1463 3208.07 0.1248 2.87636 4.41

31.9512 3909.20 0.1560 2.79877 5.38

33.1011 2415.68 0.1872 2.70412 3.32

33.4482 1483.40 0.1872 2.67685 2.04

34.0593 9996.43 0.2028 2.63021 13.75

34.8632 6370.44 0.2028 2.57137 8.76

35.0955 3176.40 0.1092 2.55488 4.37

35.9193 4930.68 0.2028 2.49815 6.78

36.4557 1816.82 0.1092 2.46262 2.50

36.8016 12666.84 0.2028 2.44026 17.42

37.0816 3874.77 0.2184 2.42247 5.33

37.9077 1556.53 0.2184 2.37157 2.14

38.4661 2055.02 0.1560 2.33841 2.83

38.6659 3561.10 0.1248 2.32679 4.90

38.8999 2595.21 0.1248 2.31332 3.57

39.5529 483.59 0.1872 2.27663 0.66

40.0729 1196.25 0.1248 2.24827 1.64

40.4331 913.59 0.2028 2.22907 1.26

41.3218 2816.77 0.1872 2.18316 3.87 [00176] In a further particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen malate is nicotinamide-p-D-ribofuranoside L-hydrogen malate, which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 2, below, ± 0.2 degrees two theta:

Table 2

Pos. [°2Th.l Height [cts] FWHM Left [°2Th.] d-spacing [A] Rel. Int. [%]

6.6733 11000.76 0.1279 13.24569 8.35

11.6730 10108.79 0.1023 7.58124 7.67

12.6182 2979.47 0.1023 7.01537 2.26

13.2792 4005.91 0.1023 6.66763 3.04

14.0796 1500.07 0.0895 6.29033 1.14

15.8520 18627.05 0.1151 5.59079 14.14

16.6325 17905.54 0.1279 5.33014 13.59

17.0744 24889.77 0.1407 5.19318 18.90

17.7100 39009.26 0.1279 5.00821 29.62

18.6845 11202.45 0.1151 4.74915 8.50

19.8229 39113.57 0.1023 4.47890 29.70

19.9594 30901.54 0.0895 4.44858 23.46

21.4914 131716.20 0.1535 4.13481 100.00

21.9147 8196.29 0.1279 4.05590 6.22

22.6727 4614.03 0.1151 3.92199 3.50

23.3985 4580.59 0.1023 3.80195 3.48

23.5603 2609.14 0.0768 3.77619 1.98

24.4454 15991.37 0.1407 3.64145 12.14

25.0307 5436.84 0.1151 3.55761 4.13

25.3173 14403.35 0.1407 3.51797 10.94

25.7774 39496.78 0.1279 3.45622 29.99

26.5990 530.11 0.0768 3.35130 0.40

27.2687 37878.08 0.1535 3.27050 28.76

27.7679 8088.77 0.1407 3.21283 6.14

28.5924 37492.90 0.1407 3.12203 28.46

29.4458 10235.99 0.1535 3.03346 7.77

29.9251 1263.01 0.1023 2.98595 0.96

30.3346 1771.52 0.1279 2.94658 1.34

30.9962 7832.28 0.1407 2.88517 5.95

31.9611 3386.65 0.1151 2.80024 2.57

32.3205 3078.07 0.1151 2.76992 2.34

32.6276 5095.47 0.1407 2.74454 3.87

33.2109 2336.00 0.1151 2.69767 1.77

33.5827 2533.18 0.1791 2.66864 1.92

34.4375 8372.54 0.1092 2.60218 6.36

34.5287 8604.75 0.0624 2.60196 6.53

35.2507 1734.20 0.1872 2.54399 1.32

35.9225 627.59 0.1560 2.49794 0.48

36.3727 1521.95 0.1560 2.46805 1.16

36.7591 10921.08 0.0624 2.44299 8.29

36.8558 16598.23 0.0780 2.43680 12.60

36.9072 15801.89 0.0624 2.43353 12.00

37.0273 9229.76 0.0780 2.43193 7.01

37.5024 915.96 0.1248 2.39626 0.70

37.6170 1026.81 0.1248 2.38922 0.78

37.9992 4085.21 0.1716 2.36606 3.10

38.3253 2144.23 0.1092 2.34668 1.63

38.7147 621.22 0.1560 2.32397 0.47

39.3994 2599.18 0.1404 2.28514 1.97

40.1021 988.71 0.1248 2.24670 0.75 [00177] In a further particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen malate is nicotinamide-p-D-ribofuranoside DL-hydrogen malate, which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 3, below, ± 0.2 degrees two theta:

Table 3

Pos. [°2Th.] Height cts\ FWHM Left [°2Th.] d-spacing [A] Rel. Int. \%]

6.4916 602.91 0.2047 13.61608 2.47

12.6712 9566.63 0.1919 6.98619 39.22

13.5865 1644.76 0.3070 6.51749 6.74

14.8721 5163.66 0.3070 5.95686 21.17

16.6660 14179.37 0.2430 5.31953 58.13

16.9489 7986.14 0.1279 5.23135 32.74

17.7388 3121.02 0.1791 5.00015 12.79

19.0726 3887.84 0.3582 4.65339 15.94

20.0028 1196.35 0.2558 4.43904 4.90

20.8961 1618.71 0.3070 4.25124 6.64

21.6668 3108.24 0.1791 4.10174 12.74

22.5350 13238.45 0.2558 3.94563 54.27

23.1389 8854.70 0.1151 3.84401 36.30

24.1793 24392.79 0.2686 3.68090 100.00

24.9889 9891.47 0.1151 3.56347 40.55

25.9744 12996.05 0.1407 3.43045 53.28

26.7055 4918.49 0.2814 3.33817 20.16

27.4357 3377.82 0.3326 3.25097 13.85

28.7541 1330.72 0.3582 3.10484 5.46

29.6501 881.37 0.1791 3.01302 3.61

30.4640 1495.16 0.2558 2.93435 6.13

31.0878 1291.15 0.2303 2.87689 5.29

32.0173 1193.11 0.3070 2.79545 4.89

33.4314 911.84 0.2047 2.68037 3.74

34.0539 3246.16 0.2558 2.63279 13.31

35.0647 1874.40 0.2047 2.55917 7.68

35.9624 1143.74 0.3070 2.49733 4.69

36.7801 5938.21 0.3582 2.44366 24.34

37.9474 612.44 0.2047 2.37113 2.51

38.5227 1356.14 0.2558 2.33704 5.56

40.1563 339.33 0.2558 2.24566 1.39

41.3746 1129.63 0.2047 2.18231 4.63

43.0838 521.75 0.3070 2.09961 2.14

[00178] In a further particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen tartrate is nicotinamide-p-D-ribofuranoside D-hydrogen tartrate monohydrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 4, below, ± 0.2 degrees two theta:

Table 4

Pos. °2Th-l Height [ctsl FWHM Left [°2Th.] d-spacing [A] Rel. Int. %]

8.4427 1105.85 0.1535 10.47327 1.22

11.5955 4172.99 0.1279 7.63174 4.61

12.2064 14705.94 0.1791 7.25111 16.24

13.0444 3289.98 0.0640 6.78714 3.63

13.5285 467.19 0.2047 6.54533 0.52

14.2848 1275.48 0.1535 6.20043 1.41

16.3545 21575.71 0.1404 5.41564 23.83

16.4347 15155.18 0.0780 5.40278 16.74

16.8125 4155.81 0.1560 5.26914 4.59

17.4631 12385.81 0.2028 5.07426 13.68

17.7789 3027.92 0.1872 4.98483 3.34

19.2171 2784.15 0.1560 4.61489 3.08

20.4255 3513.64 0.1872 4.34452 3.88

20.8956 4537.86 0.2028 4.24783 5.01

21.2720 6611.82 0.2028 4.17350 7.30

21.6994 70686.05 0.2652 4.09226 78.08

22.4487 2507.47 0.1560 3.95732 2.77

23.2293 33381.43 0.2184 3.82609 36.87

24.0319 90535.69 0.2184 3.70009 100.00

24.6286 18789.44 0.2496 3.61177 20.75

25.1774 1988.68 0.1872 3.53428 2.20

25.9477 2843.74 0.0936 3.43108 3.14

26.2952 18820.31 0.2496 3.38653 20.79

27.1345 12051.06 0.1560 3.28364 13.31

27.2135 8697.14 0.0780 3.28243 9.61

27.8905 9546.45 0.2496 3.19633 10.54

28.7630 14348.07 0.2184 3.10133 15.85

29.7764 29336.40 0.2496 2.99805 32.40

30.1789 1742.47 0.1560 2.95897 1.92

31.3589 2575.16 0.1404 2.85027 2.84

31.6114 6597.81 0.2028 2.82807 7.29

31.9725 5471.62 0.0624 2.79695 6.04

32.0262 4966.30 0.0936 2.79238 5.49

32.3674 2226.55 0.1248 2.76372 2.46

32.9500 4735.31 0.1872 2.71618 5.23

33.5558 3636.60 0.1560 2.66851 4.02

33.8129 6593.61 0.2496 2.64881 7.28

34.4780 3327.54 0.0780 2.59922 3.68

34.5356 3466.61 0.0936 2.59502 3.83

34.9811 3563.42 0.0780 2.56298 3.94

35.2429 3201.57 0.1560 2.54453 3.54

35.5541 1707.94 0.2184 2.52297 1.89

35.9811 1583.66 0.2184 2.49401 1.75

36.5723 4931.96 0.2340 2.45504 5.45

36.8813 2777.94 0.0780 2.43517 3.07

36.9482 3348.58 0.0936 2.43092 3.70

37.5567 11857.18 0.1248 2.39292 13.10

37.6362 10096.73 0.1404 2.38805 11.15

37.9557 1772.71 0.0936 2.36868 1.96

38.8483 1366.78 0.2496

2.31628 1.51 [00179] In a further particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen tartrate is nicotinamide-p-L-ribofuranoside L-hydrogen tartrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 5, below, ± 0.2 degrees two theta:

Table 5

Pos. [°2Th.1 Height fcts] FWHM Left [°2Th.l d-spacin [A] Rel. Int. f%]

11.5117 11200.84 0.1535 7.68714 7.48

12.5883 4412.06 0.1279 7.03201 2.95

13.1382 5170.21 0.1407 6.73885 3.45

15.2469 8205.64 0.1535 5.81130 5.48

16.5219 3562.59 0.1407 5.36559 2.38

17.0294 46534.70 0.2175 5.20680 31.08

18.1885 3338.98 0.1279 4.87754 2.23

19.8576 1936.08 0.0895 4.47116 1.29

20.4805 370.08 0.1279 4.33657 0.25

21.2805 10137.23 0.1279 4.17530 6.77

22.1515 19394.41 0.1535 4.01307 12.96

22.7119 149703.60 0.1663 3.91531 100.00

23.2457 5221.79 0.0512 3.82660 3.49

23.6134 55914.11 0.1663 3.76782 37.35

24.0980 4114.15 0.0895 3.69314 2.75

24.4411 7765.26 0.1407 3.64207 5.19

24.7474 2024.08 0.1151 3.59769 1.35

25.2253 3310.99 0.1279 3.53061 2.21

25.6075 6304.59 0.1663 3.47876 4.21

26.0932 5687.76 0.1407 3.41511 3.80

26.7150 7166.98 0.1535 3.33701 4.79

27.5250 15137.56 0.2047 3.24062 10.11

27.8002 10629.70 0.1407 3.20916 7.10

29.8120 9459.96 0.1407 2.99703 6.32

30.1918 1599.73 0.1023 2.96019 1.07

31.1237 5868.31 0.1535 2.87364 3.92

31.4626 2170.24 0.2303 2.84346 1.45

32.9642 1814.09 0.0780 2.71504 1.21

33.0404 1877.55 0.0640 2.71119 1.25

33.2757 1050.97 0.0768 2.69256 0.70

33.4753 934.01 0.1023 2.67696 0.62

34.3911 2124.57 0.1023 2.60774 1.42

35.0605 9970.35 0.1560 2.55736 6.66

35.1625 8673.63 0.0936 2.55651 5.79

35.5173 3085.28 0.0624 2.52551 2.06

35.7881 10815.35 0.1716 2.50701 7.22

36.4366 3605.79 0.1716 2.46386 2.41

36.9228 808.98 0.2496 2.43253 0.54

37.5169 5337.75 0.1560 2.39536 3.57

38.2736 1182.17 0.2184 2.34973 0.79

38.8883 2409.84 0.1716 2.31399 1.61

39.6760 3066.92 0.1404 2.26985 2.05

40.2830 6176.85 0.1716 2.23703 4.13

40.5831 3705.39 0.0936 2.22118 2.48

41.7493 674.67 0.1872 2.16179 0.45

42.1741 751.98 0.1872 2.14099 0.50

42.5125 407.16 0.1404 2.12473 0.27

43.1209 825.80 0.0780 2.09615 0.55

43.9559 380.32 0.0936 2.05825 0.25 44.1732 743.15 0.0936 2.04863 0.50 [00180] In a further particularly preferred embodiment, the crystalline nicotinamide-p-D- ribofuranoside hydrogen tartrate is nicotinamide-p-D-ribofuranoside DL-hydrogen tartrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 6, below, ± 0.2 degrees two theta:

Table 6

Pos. °2Th.1 Height cts] FWHM Left [°2Th.l d- spacing [A] Rel. Int. \%]

8.3072 551.28 0.2047 10.64375 1.39

11.4842 12590.46 0.0640 7.70547 31.84

11.5514 14904.11 0.1151 7.66075 37.70

12.0939 5535.53 0.1151 7.31835 14.00

12.6356 9270.40 0.1535 7.00577 23.45

13.1792 7450.29 0.1663 6.71800 18.84

14.1441 345.14 0.1535 6.26180 0.87

15.3154 6761.68 0.1535 5.78544 17.10

16.2510 6902.60 0.1663 5.45441 17.46

16.6164 4425.97 0.1407 5.33529 11.19

17.0694 38995.42 0.2047 5.19469 98.63

17.3813 4647.82 0.0512 5.10218 11.76

17.6574 1047.06 0.1023 5.02301 2.65

18.2347 2589.27 0.1407 4.86527 6.55

19.1062 673.09 0.1535 4.64527 1.70

19.9124 1996.71 0.1535 4.45898 5.05

20.3072 887.20 0.1279 4.37317 2.24

20.7939 1891.47 0.1535 4.27191 4.78

21.3241 10559.20 0.1535 4.16688 26.71

21.5806 21215.64 0.1663 4.11792 53.66

22.2002 22505.15 0.1919 4.00438 56.92

22.7919 39538.58 0.1919 3.90173 100.00

23.1194 12527.96 0.1535 3.84721 31.69

23.6904 23665.39 0.1535 3.75575 59.85

23.9145 29131.82 0.1279 3.72107 73.68

24.1548 9173.54 0.0895 3.68459 23.20

24.5068 12495.64 0.1791 3.63246 31.60

25.3161 1841.17 0.1279 3.51815 4.66

25.6584 7132.62 0.1407 3.47198 18.04

26.1650 7886.89 0.1663 3.40590 19.95

26.7609 3343.45 0.1023 3.33139 8.46

27.0106 3166.41 0.1023 3.30116 8.01

27.5367 7146.89 0.1407 3.23928 18.08

27.7875 11104.30 0.1535 3.21060 28.08

28.6467 3577.53 0.1535 3.11623 9.05

29.6650 8795.23 0.1279 3.01154 22.24

29.8675 7541.81 0.1023 2.99158 19.07

30.2186 1849.66 0.1279 2.95762 4.68

31.2001 4758.17 0.1791 2.86678 12.03

31.4762 3632.98 0.0768 2.84227 9.19

31.8369 1281.77 0.1279 2.81088 3.24

32.2436 301.91 0.1535 2.77635 0.76

32.8599 1056.56 0.1535 2.72567 2.67

33.3306 1490.86 0.1023 2.68825 3.77

33.6389 1842.81 0.1791 2.66431 4.66

34.4485 2040.78 0.1791 2.60353 5.16

34.7957 2063.81 0.1279 2.57834 5.22

35.1573 6826.29 0.0936 2.55053 17.26

35.2409 5684.59 0.0768 2.54678 14.38

35.5944 3446.74 0.0768 2.52229 8.72 [00181 ] In a further particularly preferred embodiment, the crystalline nicotinamide- 2, 3, 5-0-triacetyl- -D-ribofuranoside hydrogen tartrate is nicotinamide-2, 3, 5-triacetyl-0-p- D-ribofuranoside L-hydrogen tartrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 7, below, ± 0.2 degrees two theta:

Table 7

Pos. r°2Th.i Height [cts] FWHM Left [°2Th.l d-spacing [A] Rel. Int. [%]

9.3064 2347.46 0.0895 9.50315 3.00

10.7524 54988.21 0.2047 8.22821 70.17

12.6167 7227.54 0.1535 7.01622 9.22

13.7645 49185.18 0.2047 6.43363 62.76

14.5019 23374.03 0.2175 6.10811 29.83

16.5953 8289.38 0.2047 5.34201 10.58

17.7919 10891.17 0.1919 4.98534 13.90

18.2775 39457.79 0.2047 4.85397 50.35

18.4595 15797.39 0.0768 4.80652 20.16

19.4199 30898.77 0.1919 4.57093 39.43

20.7987 74506.22 0.2175 4.27092 95.08

21.4057 29048.75 0.1663 4.15117 37.07

21.7760 78364.38 0.2047 4.08141 100.00

22.1876 17507.69 0.1791 4.00662 22.34

22.5630 5652.40 0.1151 3.94079 7.21

22.8293 7556.27 0.1151 3.89543 9.64

23.6771 36209.59 0.1919 3.75783 46.21

24.2704 5293.40 0.1663 3.66730 6.75

25.1652 13110.92 0.1663 3.53890 16.73

25.6520 29248.77 0.1919 3.47283 37.32

27.2015 3937.84 0.1023 3.27842 5.03

27.5402 17275.90 0.1663 3.23887 22.05

27.8198 12918.63 0.0895 3.20695 16.49

28.5481 970.62 0.1279 3.12677 1.24

28.8967 3057.58 0.1279 3.08984 3.90

29.1513 7076.72 0.0640 3.06343 9.03

29.6275 17107.02 0.1407 3.01527 21.83

29.8910 9269.72 0.0895 2.98929 11.83

30.2515 8260.90 0.1535 2.95448 10.54

31.2838 5141.01 0.1919 2.85930 6.56

31.9853 3594.26 0.1023 2.79818 4.59

32.1680 3037.39 0.1791 2.78270 3.88

32.7773 523.69 0.1023 2.73235 0.67

33.3139 3622.17 0.0640 2.68956 4.62

33.9915 3211.57 0.1535 2.63748 4.10

34.5275 2365.82 0.1407 2.59776 3.02

35.1433 4786.90 0.1535 2.55363 6.11

35.8273 1682.02 0.1279 2.50643 2.15

36.0780 6948.34 0.0780 2.48753 8.87

36.1635 8783.18 0.1151 2.48390 11.21

36.8265 8675.69 0.1560 2.43867 11.07

37.0069 13561.59 0.1404 2.42720 17.31

37.0983 11547.67 0.1092 2.42744 14.74

37.5976 2995.69 0.0936 2.39041 3.82

37.9266 7992.80 0.2652 2.37042 10.20

38.8868 1967.52 0.1872 2.31408 2.51

39.3599 1961.34 0.3120 2.28734 2.50

40.0431 2967.56 0.2808 2.24988 3.79

41.2033 2016.08 0.3120 2.18917 2.57

41.6658 1798.38 0.1560 2.16593 2.29 [00182] In a further particularly preferred embodiment, the crystalline nicotinamide- 2, 3, 5-0-triacetyl- -D-ribofuranoside hydrogen tartrate is nicotinamide-2, 3, 5-triacetyl-0-p- D-ribofuranoside D-hydrogen tartrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 8, below, ± 0.2 degrees two theta:

Table 8

Pos. [°2Th.l Height [cts] FWHM Left [°2Th.l d-spacing [A] Rel. Int. [%]

4.7520 34825.67 0.1279 18.59607 22.27

6.8248 3649.79 0.1023 12.95200 2.33

9.3927 156411.40 0.1407 9.41597 100.00

9.8311 8959.38 0.1151 8.99710 5.73

10.5898 20049.70 0.1279 8.35415 12.82

10.8918 3604.23 0.0768 8.12315 2.30

13.5669 2632.18 0.0768 6.52689 1.68

14.0604 14165.00 0.1535 6.29889 9.06

14.8805 2477.98 0.0768 5.95354 1.58

15.4419 36385.34 0.1407 5.73835 23.26

16.2548 6914.23 0.1023 5.45313 4.42

17.1363 5280.44 0.1535 5.17459 3.38

18.3514 4827.86 0.1023 4.83460 3.09

18.7218 27898.79 0.1407 4.73978 17.84

19.3655 53967.66 0.1535 4.58365 34.50

19.6270 16569.59 0.1023 4.52316 10.59

20.3529 4564.06 0.0895 4.36346 2.92

21.1360 6828.67 0.1279 4.20353 4.37

21.3815 2953.04 0.1023 4.15582 1.89

21.7618 5095.87 0.1535 4.08404 3.26

22.4599 6736.19 0.1279 3.95866 4.31

23.0021 3986.81 0.0895 3.86656 2.55

23.2351 7330.57 0.0768 3.82830 4.69

23.4473 22811.80 0.1279 3.79415 14.58

23.8524 38132.07 0.1535 3.73061 24.38

24.1716 2985.45 0.0512 3.68206 1.91

24.5306 6250.72 0.1407 3.62899 4.00

25.0542 7291.19 0.1279 3.55432 4.66

25.6757 1515.37 0.1023 3.46968 0.97

26.3310 2183.17 0.1151 3.38480 1.40

26.9259 12871.27 0.1535 3.31136 8.23

27.2043 7721.08 0.1279 3.27809 4.94

27.7527 4341.55 0.1023 3.21455 2.78

27.9615 5727.76 0.1023 3.19102 3.66

28.2032 6203.34 0.1151 3.16422 3.97

28.6321 8480.22 0.1151 3.11779 5.42

29.1374 4096.80 0.1151 3.06486 2.62

29.5708 1219.70 0.0768 3.02092 0.78

29.9108 7245.93 0.1151 2.98735 4.63

30.4399 1297.52 0.1151 2.93662 0.83

31.0508 8262.20 0.1407 2.88023 5.28

31.9092 6516.50 0.1407 2.80468 4.17

32.4553 1065.25 0.1279 2.75872 0.68

32.8369 6234.01 0.1151 2.72753 3.99

33.1800 5520.53 0.1279 2.70011 3.53

33.4767 2168.58 0.1023 2.67685 1.39

34.3025 3153.03 0.1151 2.61428 2.02

34.5793 2022.97 0.1407 2.59398 1.29

35.1728 1308.53 0.0895 2.55156 0.84 36.3834 468.74 0.2047 2.46939 0.30 [00183] In a further particularly preferred embodiment, the crystalline nicotinamide- b-D-ribofuranoside hydrogen tartrate is anhydrous nicotinamide-p-D-ribofuranoside D- hydrogen tartrate which may be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 9, below, ± 0.2 degrees two theta:

Table 9

11.5441 54773)5 0.1663 7.66563 7J4

12.8809 19026.31 0.1919 6,87292 25,50

13.6583 2145.15 0.2047 6.48342 2.87

14.7982 2238.27 0.2047 5.98644 3.00

16.3923 18852.04 1 1663 5.40772 25,2ft

17.4989 31734.1)4 0.1791 5.06958 42,53

18,2961 44664 0.1279 4.84910 0.60

19.6742 6616.60 0.2814 4.51243 8-87

20.4519 3327.08 0.1535 4.34256 4.46

21.3667 74623.20 0.191 4.15865 100.00

22.2026 58527.36 0.1919 4.00395 7«,43

22.9226 1946.12 0.1535 3.8 962 2,61

2.3..30.38 1293.31 0.1 23 5.81718 1.73

24.1005 10296.35 0.1535 3.69276 13 JO

24.3711 7580.65 0.1535 3.65237 10, 16

25. ⁽ 1633 12509.80 0.1535 3.55316 16,76

26.1075 13375.49 0.1663 3.41327 17,92

27.1046 4134.24 0.1585 3,28992 5,54

27J697 5451.44 0.1023 3.25865 7.31

27,6019 41)53.75 0, 1023 3.23177 5.43

28.3123 9045.58 0 1535 3.15228 12.12

28.7576 2770 _, 85 0.1791 3.10447 8,71

29.7420 4272.59 0.1151 3.00392 5.73

.30.2505 2905.11 02303 2.95457 3.89

30.6625 1476.96 0.1 91 2.91581 1.98

31.8526 3847.53 0.1151 2.80953 5,16

32.3522 1209.36 02047 2.76727 1.62

33.2255 6634.29 0.1407 2.69651 8.89

33.4595 2216.67 0.1023 2.67819 2.97

33.9924 5402.04 0.1279 2.63741 7,24

34.5081 725.11 0.1279 2.59917 0.97

34.8645 1193.46 0.1791 2.57341 1.60

35..3079 2701.51 0.1535 2.54210 3.62

35.5426 221(145 0 127 2.52588 2,9ft

36.3433 3310.00 0.1407 2.47202 4.44

36.8835 6123.57 0.1535 2.43705 8,21

37.7104 1917.12 0.1023 2.38549 2.57

38.9440 2230.62 0.1279 2.31272 2.99

39.2338 2324.44 0.0768 2.29630 3, 1 1

39.8924 4022.79 0.1151 2.25990 5,39

40.56,27 1485.94 0.1701 2.22409 1.99

41.6641 «! 4,42 0.1023 2.16781 1.09

41.9184 1443.54 0.1535 2.15525 1.93

42.5626 209 .08 0.1 91 2.12410 2.81

43.3574 415,83 0 1535 2.08699 <156

44.0950 235,65 0.3070 2.05378 <1,32

[00184] Accordingly, in particularly preferred embodiments, the invention relates to crystalline nicotinamide-p-D-ribofuranoside salts selected from the group consisting of:

[00185] nicotinamide-p-D-ribofuranoside D-hydrogen malate characterized by a powder X-ray diffraction pattern as defined in Fig. 1 ; [00186] nicotinamide-p-D-ribofuranoside L-hydrogen malate characterized by a powder X-ray diffraction pattern as defined in Fig. 2;

[00187] nicotinamide-p-D-ribofuranoside DL-hydrogen malate characterized by a powder X-ray diffraction pattern as defined in Fig. 3;

[00188] nicotinamide-p-D-ribofuranoside D-hydrogen tartrate monohydrate characterized by a powder X-ray diffraction pattern as defined in Fig. 4;

[00189] nicotinamide-p-D-ribofuranoside L-hydrogen tartrate characterized by a powder X-ray diffraction pattern as defined in Fig. 5;

[00190] nicotinamide-p-D-ribofuranoside DL-hydrogen tartrate characterized by a powder X-ray diffraction pattern as defined in Fig. 6;

[00191 ] nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside L-hydrogen tartrate characterized by a powder X-ray diffraction pattern as defined in Fig. 7;

[00192] nicotinamide-2, 3, 5-O-triacetyl-p-D-ribofuranoside D-hydrogen tartrate characterized by a powder X-ray diffraction pattern as defined in Fig. 8;

[00193] anhydrous nicotinamide-p-D-ribofuranoside D-hydrogen tartrate characterized by a powder X-ray diffraction pattern as defined in Fig. 9.

[00194] In another embodiment of the fourth aspect, the invention relates to a nicotinamide-p-D-ribofuranoside salt obtainable by a method as defined in any one of the embodiments of the first or second aspect.

Fifth aspect: Nutritional supplement

[00195] According to a fifth aspect, the invention relates to a nutritional supplement comprising a nicotinamide-p-D-ribofuranoside salt obtained according to a method as defined in the first or second aspect or comprising a nicotinamide-p-D-ribofuranoside salt as defined in the fourth aspect.

[00196] Suitable methods for making such nutritional supplement comprising a nicotinamide-p-D-ribofuranoside salt are known in the art or may be prepared analogously to such known methods. Sixth aspect: Pharmaceutical composition

[00197] According to a sixth aspect, the invention relates to a pharmaceutical composition comprising a nicotinamide-p-D-ribofuranoside salt obtained according to a method as defined in the first or second aspect or comprising a nicotinamide-p-D- ribofuranoside salt as defined in the fourth aspect.

[00198] The pharmaceutical composition may be used in the prevention or treatment of diseases or conditions associated with the nicotinamide riboside kinase pathway or other pathways of NAD ⁺ biosynthesis. These pathways are known in the art.

Seventh aspect: Use of the compounds defined in the fourth aspect as starting material for a chemical synthesis

[00199] The crystalline compounds as defined in the fourth aspect, due to their purity, and ease of access may serve as starting material for making other nicotinamide-B-D- ribofuranoside salts, e.g. the commercially available chloride, or related compounds, i.e. they may be used as starting materials in a chemical synthesis.

[00200] According to a seventh aspect, the invention relates to a method of performing a chemical synthesis, comprising step (A):

(A) providing a nicotinamide-p-D-ribofuranoside salt obtained by the method as defined in the first, second or third aspect, or providing a compound defined in the fourth aspect.

Eighth aspect: Preparation of nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside triflate or nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside chloride, bromide, iodide, nonaflate, fluorosulfonate or perchlorate

[00201 ] The inventors have further modified the method developed by Tanimori as disclosed in the third aspect. It was hitherto believed that this known method requires a tremendous excess of 7.3 equivalents TMSOTf related to one equivalent tetra-O-acyl-b- D-ribofuranose in order to form nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside triflate being sufficiently pure for subsequent reactions. [00202] The inventors of the present invention unexpectedly discovered that the use of much less TMSOTf resulted in a product having a higher purity compared to the product obtained with the tremendous molar excess of TMSOTf. This is particularly advantageous under economic aspects.

[00203] Accordingly, in said eighth aspect, the invention relates to a method of making a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside triflate, the method comprising step (A):

(A) reacting nicotinamide with tetra-O-acyl-B-D-ribofuranose in presence of 0.9 to 1.5 mole equivalents TMSOTf related to one mole tetra-O-acyl-B-D-ribofuranose.

[00204] Preferably, 1.0 to 1.5 mole equivalent TMSOTf are used, more preferably 1.0 to 1.3 mole equivalent, still more preferred 1.0 to 1.2 mole equivalent.

[00205] Preferably, acetonitrile is used as solvent.

[00206] Preferably, the reaction is carried out in a temperature range of from 10 to 40 °C, more preferably 20 to 30 °C.

[00207] Nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside triflate may be obtained after removing the solvent as amorphous foam.

[00208] The acyl groups may then be cleaved according to known methods to afford the nicotinamide-p-D-ribofuranoside triflate.

[00209] Both the acylated product as well as the deacylated product may be used in the respective methods according to the invention as defined in the first, the second and the third aspect.

[00210] In one embodiment, nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside triflate is not isolated prior to salt metathesis or prior to deacylation.

[0021 1 ] The iodide may be prepared in an analogous manner. Accordingly, in this aspect, the invention relates to a method of making a nicotinamide-2, 3, 5-tri-0-acyl-p-D- ribofuranoside iodide, the method comprising step (A): (A) reacting nicotinamide with tetra-O-acyl-B-D-ribofuranose in presence of 0.9 to 1.5 mole equivalents TMSI related to one mole tetra-O-acyl-B-D-ribofuranose.

[00212] Preferably, the reaction is carried out in a temperature range of from 10 to 50 °C, more preferably 20 to 40 °C.

[00213] This reaction may also be extended to the preparation of the bromide, chloride, nonaflate, fluorosulfonate and perchlorate. Accordingly, in one embodiment, this aspect also relates to a method of making a nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside bromide, chloride, nonaflate, fluorosulfonate or perchlorate, the method comprising step (A):

(A) reacting nicotinamide with tetra-O-acyl-B-D-ribofuranose in presence of 0.9 to 1.5 mole equivalents TMSBr, TMSCI, TMSOSO2C4F9, TMSOSO2F or TMSOCIO3 related to one mole tetra-O-acyl-B-D-ribofuranose.

[00214] The synthesis of the iodide is particularly preferred due to high yield and purity of the formed product and economic advantages.

Ninth aspect: Nicotinamide-p-D-ribofuranoside iodide, nonafluorobutanesulfonate, fluorosulfonate, perchlorate, nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside iodide, nonafluorobutanesulfonate, fluorosulfonate, perchlorate

[00215] According to the ninth aspect, the invention relates to

[00216] nicotinamide-p-D-ribofuranoside iodide, nonafluorobutanesulfonate, fluorosulfonate or perchlorate of formula

[00217] and nicotinamide-2, 3, 5-tri-0-acyl-p-D-ribofuranoside iodide, nonafluorobutanesulfonate, fluorosulfonate or perchlorate of formula wherein R is an acyl group independently selected from alkyl carbonyl, aryl carbonyl and heteroaryl carbonyl, preferably from CM O alkyl carbonyl and benzoyl, and is more preferably acetyl, and wherein R is optionally independently substituted with one or more substituents selected from: C1-6 alkyl, C1-6 alkoxy, C1-6 thioalkyl, halogen, nitro, cyano, NH(CI-6 alkyl), N(Ci-e alkyl) ₂ , and S02N(Ci-6 alkyl) ₂ ; preferably wherein R is acetyl.

[00218] In another aspect of the invention, nicotinamide used in the synthesis according to the invention as in steps (X) and (Y) as defined in the first aspect and second aspect is used in the form of a precursor, namely in the form of a nicotinic acid ester.

[00219] In one embodiment, the ester moiety is selected from C _{M O} alkoxy which can be branched or unbranched or cyclic. In another embodiment, the ester moiety is phenoxy, optionally substituted. In another embodiment, the ester moiety is benzyloxy, optionally substituted. Herein, the term“optionally substituted” refers to C1-6 alkyl, C1-6 alkoxy, C1-6 thioalkyl, halogen, nitro, cyano, NH(Ci-e alkyl), N(C _I-6 alkyl) ₂ , and S0 ₂ N(Ci- ₆ alkyl) ₂ .

[00220] Subsequently, the respective compounds bearing a nicotinic acid ester moiety may be subjected to salt metathesis as described above.

[00221 ] Finally, the nicotinic ester moiety of the respective compounds is transferred with ammonia into a nicotinamide moiety.

[00222] In another aspect, the invention relates to a method of making a second nicotinamide-p-D-ribofuranoside salt from a first nicotinamide-p-D-ribofuranoside salt or a second nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt from a first nicotinamide- 2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt, comprising steps (A1 ) and (A2): (A1 ) reacting NH ₃ or NR ¹ H ₂ or NR ¹ R ² H or NR ¹ R ² R ³ or [NR ¹ R ² R ³ R ⁴ ]OH with an acid to afford an ammonium salt, wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from C1-12 alkyl and aryl, optionally substituted.

(A2) reacting the first nicotinamide-p-D-ribofuranoside salt or the first nicotinamide- 2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt with the ammonium salt from step (A1 ) to perform salt metathesis comprising counter-ion exchange to afford the second nicotinamide-p-D-ribofuranoside salt or the second nicotinamide-2, 3, 5-tri-O-acyl- p-D-ribofuranoside salt.

[00223] In a preferred embodiment, NR ¹ R ² R ³ or [NR ¹ R ² R ³ R ⁴ ]OH is used in step (A1 ).

[00224] The acetyl residue used in the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt is defined above.

[00225] Preferably, step (A2) is performed in a solvent comprising an alcohol selected from the group consisting of methanol, ethanol, a propanol or a butanol or a mixture of two or more thereof, optionally the solvent or the alcohol comprising water; or the solvent is selected from the group consisting of methanol, ethanol, a propanol or a butanol or a mixture of two or more thereof, optionally comprising water.

[00226] In another aspect, the invention relates to the use of an ammonium salt comprising NH ₄ ⁺ or NR ¹ H ₃ ⁺ or NR ¹ R ² H ₂ ⁺ or NR ¹ R ² R ³ H ⁺ or [NR ¹ R ² R ³ R ⁴ ] ⁺ , wherein R ¹ , R ² , R ³ and R ⁴ are independently selected from Ci-i ₂ alkyl and aryl, optionally substituted, in a salt metathesis reaction.

[00227] Preferably, a nicotinamide-p-D-ribofuranoside salt or a nicotinamide-2, 3, 5-tri-O- acyl-p-D-ribofuranoside salt is subjected to salt metathesis.

[00228] The acetyl residue used in the nicotinamide-2, 3, 5-tri-O-acyl-p-D-ribofuranoside salt is defined above.

[00229] Preferably, the salt metathesis reaction is performed in a solvent comprising an alcohol selected from the group consisting of methanol, ethanol, a propanol or a butanol or a mixture of two or more thereof, optionally the solvent or the alcohol comprising water; or the solvent is selected from the group consisting of methanol, ethanol, a propanol or a butanol or a mixture of two or more thereof, optionally comprising water. [00230] The following Examples further illustrate the present invention.

EXAMPLES

Example 1 : Preparation of nicotinamide-2, 3, 5-tri-0-acetyl-p-D-ribofuranoside bromide used as starting salt in step (A) of the method according to the second or third aspect

[00231 ] 274 g b-D-ribofuranose 1 ,2,3,5-tetraacetate were dissolved in 274 ml acetonitrile. 180 ml of hydrogen bromide in glacial acetic acid (concentration 33 %) were added to the stirred solution while keeping the temperature between 0 °C and 5 °C. Stirring was continued for further 15 minutes. 41 g of nicotinamide was added while stirring for another 15 minutes. A hot (70 °C) solution of 96 g nicotinamide in 700 ml acetonitrile was then added whereupon the mixture was cooled to about 0 °C to 5 °C. Stirring was continued for 15 h, followed by filtration of the formed suspension. The filtrate was subjected to distillation. The obtained oily residue was diluted with acetone, resulting in crystallization of the title product. The title product was filtered and dried to give 167 g (43 % yield) of an almost colorless product; Mp: 133-134 °C.

¹ H-NMR (400 MHz, DMSO-d6): 2.09 (s, 6H), 2.13 (s, 3H) 4.45 (m, 2H, H5’), 4.69 (m, 1 H, H4’), 5.43 (t, 1 H, H3’), 5.62 (dd, 1 H, H2’), 6.69 (d, 1 H, H1’), 8.23 (s, 1 H, NH), 8.41 (dd, 1 H, H5), 8.74 (s, 1 H, NH), 9.13 (d, 1 H, H4), 9.28 (d, 1 H, H6), 9.49 (s, 1 H, H2);

¹³ C-NMR (100 MHz, DMSO-d6): 20.3, 20.4, 20.5, 62.1 (C5‘), 68.7 (C3‘), 75.3 (C2‘), 81.8 (C4‘), 97.2 (C1‘), 128.1 (C5), 133.9 (C3), 141.2 (C2), 143.1 (C6), 145.5 (C4), 162.7 (CONH2), 169.2, 169.4, 170.1

Example 2: Preparation of nicotinamide-p-D-ribofuranoside bromide used as starting salt in step (A) in the method according to the first aspect

[00232] 167 g of the product obtained in Example 1 were dissolved in 870 ml methanol. 135 ml of hydrogen bromide in acetic acid (concentration 33 %) were then added to the stirred solution while keeping the temperature between 5 °C to 10 °C. The resulting mixture was stirred for two days at 20 °C wherein the product started crystallizing. The formed crystals were filtered off, washed with isopropanol and dried. The title compound was obtained in a yield of 77 g (63 %) as a pale yellow crystalline powder; Mp: 1 18-1 19 °C.

¹ H-NMR (400 MHz, D ₂ 0): 3.83 (dd, 1 H, H5’), 3.98 (dd, 1 H, H5’), 4.29 (t, 1 H, H3’), 4.39- 4.48 (m, 2H, H4\ H2’), 6.18 (d, 1 H, H1’), 8.22 (t, 1 H, H5), 8.91 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.52 (s, 1 H, H2);

¹³ C-NMR (100 MHz, D2O): 60.0 (C5‘), 69.5 (C3‘), 77.2 (C2‘), 87.5 (C4‘), 99.7 (C1‘), 128.3 (C5), 133.7 (C3), 140.2 (C2), 142.5 (C6), 145.5 (C4), 165.6 (CONH2).

Example 3: Preparation of nicotinamide-fi-D-ribofuranoside L-hydrogen tartrate from nicotinamide-fi-D-ribofuranoside bromide using various ammonium L- hydrogen tartrate salts for salt metathesis

Example 3a: Use of TEA · L-hydrogen tartrate

[00233] 3.90 g of L-tartaric acid (26.0 mMol) were dissolved in 10 ml methanol with stirring. The colorless solution was cooled in an ice bath and 3.64 ml triethylamine (26.1 mMol) added. The pH of the slightly yellowish solution was around 4 - 4.5. In this manner 15 ml of a 1.73 molar solution of TEA · L-hydrogen tartrate was prepared.

[00234] 5.8 g nicotinamide-B-D-ribofuranoside bromide (NR*Br) were dissolved with stirring in 3.5 ml water at room temperature. 10 ml methanol were added. 10 ml of the above prepared solution of triethylammonium L-hydrogen tartrate were added to the clear colorless solution. White product starts precipitating.

[00235] The suspension was stirred for a further hour at room temperature. The product was filtered, washed with methanol and dried in vacuum at 35°C. 6.62 g (95 %) of a white, crystalline powder were obtained; mp: 129 - 130 °C; IC: Residual bromide 0.20 %. The solid may be recrystallized from aqueous methanol, if desired.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.38- 4.45 (m, 2H, H4\ H2’), 4.41 (s, 2H, 2x CHOH, H-tartrate), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.52 (s, 1 H, H2). Impurities: < 1 mol% nicotinamide; 1.2 mol% TEA salt: 1.19 (t, 9H), 3.1 1 (q, 6H). Solvents: 7.3 mol% methanol: 3.25 (s, 3H).

¹³ C-NMR (100 MHz, D2O): 60.2 (C5‘), 69.7 (C3‘), 72.8 (2x CHOH, H-tartrate), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 176.3 (2x COO, H-tartrate). Impurity: 8.2, 46.6 (TEA). Solvents: 48.9 (methanol).

XRD: crystalline (Fig. 5)

Example 3b: Use of TBA · L-hydrogen tartrate

[00236] 3.90 g of L-tartaric acid (26.0 mMol) were dissolved in 10 ml methanol with stirring. The colorless solution was cooled in an ice bath and 6.3 ml tributylamine (26.0 mMol) added. The pH of the slightly yellowish solution was around 4. In this manner 17.5 ml of a 1.53 molar solution of tributylammonium L-hydrogen tartrate was prepared.

[00237] 5.80 g nicotinamide-B-D-ribofuranoside bromide were dissolved with stirring in 3.5 ml water at room temperature. 10 ml methanol were added. 1 1.1 ml of the above prepared solution of tributylammonium L-hydrogentartrate were added to the clear colorless solution. White product immediately starts crystallizing.

[00238] The suspension was stirred for a further hour at room temperature. The product was filtered, washed with methanol and dried in vacuum at 35°C. 6.37 g (91 %) of a white, crystalline powder were obtained; mp: 128°C; IC: Residual bromide 0.62 %.

[00239] Impurities (NMR): < 1 mol % nicotinamide, 2.7 mol % TBA salt: 0.84 (t, 9H), 1.28 (m, 6H), 1.58 (m, 6H), 3.04 (q, 6H); solvents: 3.7 mol % methanol: 3,25 (s, 3H).

Example 3c: Use of tetrabutylammonium · L-hydrogen tartrate [00240] 3.90 g of L-tartaric acid (26.0 mMol) were dissolved in 10 ml methanol with stirring. The colorless solution was cooled in an ice bath and 17.0 ml of a 40 % solution of tetrabutylammonium hydroxide in water (26.0 mMol) were added. The pH of the slightly yellowish solution was around 4. In this manner 29 ml of a 0.9 molar solution of tetrabutylammonium L-hydrogen tartrate was prepared.

[00241 ] 5.80 g nicotinamide-B-D-ribofuranoside bromide were dissolved with stirring in 3.5 ml water at room temperature. 10 ml methanol were added. 19.3 ml of the above prepared solution of tetrabutylammonium L-hydrogen tartrate were added to the clear colorless solution. White product starts crystallizing.

[00242] The suspension was stirred for a further hour at room temperature. The product was filtered, washed with methanol and dried in vacuum at 35°C. 5.60 g (80 %) of a white, crystalline powder were obtained; mp: 129 - 130°C; IC: Residual bromide 0.13 %.

[00243] Impurities (NMR): < 1 mol% nicotinamide; 0.35 mol% TBA salt: 0.36 (t, 9H), 1 ,27 (m, 6H), 1 ,56 (m, 6H), 3.1 1 (q, 6H); solvents: 2.4 mol% methanol: 3.26 (s, 3H).

Example 4: The following crystalline nicotinamide-fi-D-ribofuranoside salt of the table was prepared analogously to Example 3a

[00244] Table 1

Example 5: Preparation of nicotinamide-fi-D-ribofuranoside L-hydrogen malate from nicotinamide-fi-D-ribofuranoside bromide using various ammonium L- hydrogen malate salts for salt metathesis

Example 5a: Use of TEA · L-hydrogen malate [00245] 5.8 g nicotinamide-B-D-ribofuranoside bromide were suspended in 10 ml methanol upon stirring. 10 ml of a 1 .73 molar solution of triethylammonium L- hydrogen malate were added. The suspension was heated until the solids dissolved completely. After cooling, a white solid precipitated. The suspension was stirred for 30 min and then filtered. The residue was washed with methanol and dried in vacuo at 35 °C. 4.15 g (62 %) of a white crystalline powder was obtained. Mp: 1 16.5 - 1 17 °C. IC: Residual bromide 0.10 %. The product may be recrystallized from methanol, if desired.

¹ H-NMR (400 MHz, D ₂ 0): 2.53 (dd, 1 H, CH ₂ , H-malate), 2.72 (dd, 1 H, CH ₂ , H-malate), 3.81 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.29 (dd, 1 H, CHOH, H-malate), 4.38-4.45 (m, 2H, H4\ H2’), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.52 (s, 1 H, H2). Impurities: < 1 mol% nicotinamide; 0.7 mol% TEA salt: 1 .19 (t, 9H), 3.1 1 (q, 6H). Solvents: 6.3 mol% methanol: 3.25 (s, 3H).

¹³ C-NMR (100 MHz, D ₂ 0): 40.0 (CH ₂ , H-malate), 60.2 (C5‘), 68.5 (CHOH, H-malate), 69.7 (C3‘), 77.4 (C2‘), 87.7 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.7 (CONH2), 176.3 (COO, H-malate), 179.0 (COO, H-malate). Solvents: 48.9 (methanol).

XRD: crystalline (Fig. 2)

Example 5b: Use of TBA · L-hydrogen malate

[00246] 3.50 g of L-malic acid (26.0 mMol) were dissolved in 10 ml methanol with stirring. The colorless solution was cooled in an ice bath and 6.3 ml tributylamine (26.0 mMol) were added. The pH of the slightly yellowish solution was around 5. In this manner 17.5 ml of a 1.53 molar solution of tributylammonium L-hydrogen malate was prepared.

[00247] 5.80 g nicotinamide-B-D-ribofuranoside bromide were suspended in 17.5 ml methanol upon stirring. 1 1.1 ml of the above prepared solution of tributylammonium L- hydrogen malate were added. The suspension was heated until the solids dissolved completely. After colling, a white solid crystallized. The suspension was stirred for 30 min and then filtered. The residue was washed with methanol and dried in vacuo at 35°C. 4.89 g (73 %) of a white crystalline powder was obtained; mp: 1 15.5°C; IC: Residual bromide 0.64 %.

[00248] Impurities: < 1 mol% nicotinamide; 0.2 mol% TBA salt ; 2 mol% methanol.

Example 6: The following crystalline nicotinamide^-D-ribofuranoside salts of the table were prepared analogously to Example 5a

[00249] Table 2

Example 6d: Recrystallization of compound 6c to the monohydrate

[00250] 2.0 g nicotinamide-p-D-ribofuranoside D-hydrogen tartrate prepared in Example 6c were dissolved in 9 ml water. 70 ml methanol were added to the colorless solution with stirring. After approx one minute white crystals precipitated. One hour later the formed suspension was filtered. The residue was washed with methanol and dried in vacuo at 35 °C. 1.54 g (77 %) of a white crystalline powder of the monohydrate was obtained. Water content: 4.24 % (determined according to K. Fischer); Mp.: 1 15-1 16 °C; IC: Residual bromide: < 0.01 %. XRD: crystalline (Fig. 4)

Example 7: Preparation of nicotinamide-8-D-ribofuranoside meso-hydrogen tartrate

[00251 ] 0.57 g nicotinamide-B-D-ribofuranoside bromide were suspended in 1 ml methanol upon stirring. 1 ml of a 1.69 molar solution of triethylammonium meso- hydrogen tartrate was added. The suspension was heated to the boiling point and was then cooled down. The formed emulsion was dropped into 20 ml ethanol. The formed suspension was filtered and the residue was dried at room temperature in vacuo. 0.44 g (62 %) of a flaky, hygroscopic powder were obtained.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.38- 4.46 (m, 2H, H4\ H2’), 4.35 (s, 1.5H, 2x CHOH, meso-H-tartrate), 6.17 (d, 1 H, H1’), 8.21 (t, 1 H, H5), 8.91 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.53 (s, 1 H, H2). Impurities: 5 mol% nicotinamide: 7.65 (m, 1 H), 8.33 (m, 1 H), 8.68 (d, 1 H), 8.90 (s, 1 H); 10.2 mol% TEA salt: 1 .20 (t, 9H), 3.12 (q, 6H). Solvents: 16 mol% methanol: 3.25 (s, 3H); 40 mol% ethanol: 1 .09 (t, 3H), 3.56 (q, 2H).

¹³ C-NMR (100 MHz, D2O): 60.2 (C5‘), 69.7 (C3‘), 73.7 (2x CHOH, meso-H-tartrate), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 175.7 (2x COO, H-tartrate). Impurities: 125.0, 138.6, 146.0, 149.8 (nicotinamide); 8.2, 46.6 (TEA). Solvents: 48.9 (methanol); 16.8, 57.4 (ethanol).

Example 8: Preparation of nicotinamide-8-D-ribofuranoside D-glucuronate

[00252] 5.10 g of glucuronic acid were suspended in 15 ml methanol with stirring. The colorless suspension was cooled in an ice bath and 3.60 ml triethylamine added. 19.5 ml of a 1.35 molar solution of TEA · D-glucuronate were prepared.

[00253] 5.0 g nicotinamide-B-D-ribofuranoside bromide were dissolved with stirring in 3.0 ml water at room temperature. 10 ml methanol were added. 11.1 ml of the above prepared solution of triethylammonium D-glucuronate were added. The clear yellowish solution was dropped slowly to 455 ml n-butanol, wherein a white suspension was produced.

[00254] The suspension was stirred for further five hours at room temperature. The product was filtered, washed with isopropanol and dried in vacuum at 35 °C. 6.64 g of the dried crude product were dissolved in 6.6 ml water and diluted with 33 ml methanol. The yellowish solution was dropped to 550 ml butanol, wherein a white suspension was produced. The suspension was filtered, the residue was washed with isopropanol and dried at 35 °C. Mp.: 66 - 76 °C; residual bromide 1.43 % (IC).

¹ H-NMR (400 MHz, D ₂ 0): NR: 3.82 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.38-4.45 (m, 2H, H4\ H2’), 6.17 (d, 1 H, H1’), 8.21 (t, 1 H, H5), 8.91 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.53 (s, 1 H, H2); GlcUA (anomeric mixture): 3.19 (m), 3.42 (m), 3.50 (m), 3.63 (m), 4.00 (t), 4.55 (d, b-anomer), 5.14 (d, a-anomer). Impurities: 2 mol% nicotinamide; 0.9 mol% TEA salt: 1 .19 (t, 9H), 3.1 1 (q, 6H). Solvents: 23 mol% methanol: 3.26 (s, 3H); 5.7 mol% butanol: 0.80 (t, 1 H, H4), 1.25 (m, 2H, H3), 1 .43 (m, 2H, H2).

¹³ C-NMR (100 MHz, D2O): NR: 60.2 (C5‘), 69.7 (C3‘), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2); GlcUA: 71.3, 71.7, 71.8, 72.0, 72.5, 74.0, 75.5, 76.1 , 92.1 , 95.9, 175.7, 176.7. Solvents: 48.9 (methanol); 13.1 , 18.4, 33.4, 61.5 (butanol).

Example 9: Nicotinamide-B-D-ribofuranoside L-ascorbate

[00255] A crude product was prepared analogously to Example 8, however using ethanol for precipitation. 3.1 1 g of the crude product were dissolved in 1 .9 ml water. The orange clear solution was filtered and diluted with 16 ml methanol. The solution was dropped to 238 ml ethanol, wherein an orange suspension was produced. The product was isolated by filtration and dried at 35 °C. 1 .13 g of a yellowish powder were obtained (yield 36.3 %). IC: Residual bromide 0.38 %.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.38- 4.45 (m, 2H, H4\ H2’), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.52 (s, 1 H, H2); Ascorbate: 3.64 (m, 2H), 3.92 (m, 1 H), 4.43 (m, 1 H). Impurities: 16 mol% nicotinamide: 7.49 (t, 1 H), 8.13 (d, 1 H), 8.60 (d, 1 H), 8.82 (s, 1 H); no TEA salt. Solvents: 1 .3 mol% methanol: 3.25 (s, 3H); 46 mol% ethanol: 1 .08 (t, 3H), 3.55 (q, 2H).

¹³ C-NMR (100 MHz, D ₂ 0): 60.2 (C5‘), 69.7 (C3‘), 77.4 (C2‘), 87.7 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2); Ascorbate: 62.5, 69.5, 78.2, 1 13.3, 174.6, 177.2. Impurities: nicotinamide: 124.2, 129.3, 136.5, 147.6, 151 .7. Solvents: 16.8, 57.4 (ethanol).

Example 10: Nicotinamide-fi-D-ribofuranoside citrate

[00256] 5.52 g citric acid monohydrate were dissolved in 55 ml DMSO with stirring. The colorless solution was cooled in an ice bath and 12 ml triethylamine added. 73 ml of a 0.36 molar solution of TEA · citrate were prepared.

[00257] 9.0 g nicotinamide-B-D-ribofuranoside bromide were suspended in 18 ml DMSO. 73 ml of the above produced solution were added and heated to 55 °C. The brownish solution was added to 1 125 ml isopropanol, wherein a white suspension was produced. The solid was isolated by filtration and dried at 35 °C. 6.32 g (74 %) of a powder were obtained.

[00258] 3.22 g of the crude product were dissolved in a mixture of 16 ml methanol and 2 ml water. The solution was dropped to 220 ml isopropanol, wherein a white suspension was produced. The solid was isolated by filtration, washed with isopropanol and dried in vacuo at 35 °C. 2.67 of a white powder were obtained (82.9 %). IC: Residual bromide 0.19 %.

¹ H-NMR (400 MHz, D ₂ 0): 2.61 (m, 4H, CH ₂ , citrate), 3.82 (dd, 1 H, H5’), 3.97 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.38-4.46 (m, 2H, H4’, H2’), 6.17 (d, 1 H, H1’), 8.21 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.52 (s, 1 H, H2). Impurities: 6 mol% nicotinamide: 7.50 (dd, 1 H), 8.15 (m, 1 H), 8.61 (d, 1 H), 8.82 (s, 1 H); 1 .5 mol% TEA salt: 1 .19 (t, 9H), 3.1 1 (q, 6H). Solvents: 31 mol% methanol: 3.26 (s, 3H); 18 mol% isopropanol: 1 .08 (d, 6H), 3.92 (m, 1 H).

¹³ C-NMR (100 MHz, D ₂ 0): 44.6 (CH ₂ , citrate), 60.2 (C5‘), 69.7 (C3‘), 77.4 (C2‘), 87.7 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.7 (CONH2), 176.9 (2x COO, citrate), 180.0 (COO, citrate). Impurities: Nicotinamide: 124.3, 129.3, 136.7, 147.5, 151 .6; TEA salt: 8.2, 46.6. Solvents: 48.9 (methanol); 23.7, 64.2 (isopropanol).

Example 11 : Preparation of nicotinamide^-D-riboside-2, 3, 5-triacetate L- hydrogen tartrate

Example 11a: via salt metathesis from nicotinamide^-D-riboside-2, 3,5- triacetate bromide

[00259] 3.90 g L-tartaric acid were dissolved in 10 ml methanol upon stirring. The solution was cooled down to 0-5 °C. 3.64 ml triethylamine were added. The pH value was 4.1 . 15 ml of a 1 .73 molar solution of triethylammonium L-hydrogen tartrate was obtained.

[00260] 8.0 g of nicotinamide-2, 3, 5-tri-0-acetyl43 _> -D-riboside bromide were suspended in 10 ml methanol upon stirring. 10 ml of the above generated triethylammonium L-hydrogen tartrate solution were added. A white crystalline powder slowly started precipitating. The residue obtained after filtration was dried in vacuo at 35 °C. 6.00 g (65.2 %) of a white crystalline powder was obtained. Mp. 128 °C; IC: residual bromide <0.1 %.

¹ H-NMR (400 MHz, D ₂ 0): 2.08, 2.12, 2.15 (3x s, 3x 3H, COCH ₃ ), 4.43 (s, 2H, 2x CHOH, H-tartrate), 4.52 (m, 2H, H5’), 4.88 (m, 1 H, H4 ^' ), 5.44 (t, 1 H, H3’), 5.55 (dd, 1 H, H2’), 6.58 (d, 1 H, HT), 8.27 (t, 1 H, H5), 8.99 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.43 (s, 1 H, H2). Impurities: < 0.1 mol% nicotinamide; 0.6 mol% TEA salt: 1 .21 (t, 9H), 3.13 (q, 6H). Solvents: 2 mol% methanol: 3.27 (s, 3H).

¹³ C-NMR (100 MHz, D2O): 19.8, 19.9, 20.2 (3x COCH ₃ ), 62.6 (C5‘), 69.4 (C3‘), 72.8 (2x CHOH, H-tartrate), 76.3 (C2‘), 82.6 (C4‘), 97.3 (C1‘), 128.6 (C5), 134.2 (C3), 140.4 (C2), 143.1 (C6), 146.2 (C4), 165.5 (CONH2), 172.3, 172.4, 173.3 (3x CO), 176.3 (2x COO, H- tartrate).

XRD: crystalline (Fig. 7).

Example 11b: via ion exchange using an ion exchanger (for comparison) [00261 ] 145 g Ambersep 900 in the OH-form were suspended in 1 10 ml water. Subsequently, 21 g L-tartaric acid were added upon stirring. The ion exchanger loaded with L-hydrogen tartrate was isolated by filtration and washed thrice with water

[00262] 10.0 g of nicotinamide-2, 3, 5-tri-0-acetyl43 _> -D-riboside bromide were dissolved in 70 ml water upon stirring. 22 g of the loaded ion exchanger were added and stirred for 16 minutes. The ion exchanger was separated by filtration and waded twice with water. The filtrate was again subjected to 22 g of the loaded ion exchanger and washed and filtered, wherein the filtrate was collected. This was repeated twice. The filtrate was concentrated. 14.08 g of colorless oil was obtained. The oil was subjected to aqueous methanol, wherein a white suspension was obtained. 9.09 g of a white powder were obtained after filtration and drying.

[00263] 5.05 g of the amorphous product were dissolved in 25 ml methanol, wherein after some minutes crystallization started. The crystals were isolated by filtration and dried in vacuo at 35 °C. 3.92 g, mp. 130 °C. XRD was identical to the XRD of the product obtained in Example 11a.

Example 12: Preparation of nicotinamide-2, 3, 5-tri-0-acetyl-ft-D-ribofuranoside triflate

Example 12a: according to the invention

[00264] 1 1 .55 g (0.094 mole) of nicotinamide and 29.7 g (0.093 mole) of b-D- ribofuranose 1 ,2,3,5-tetraacetate were dissolved upon stirring at room temperature in 750 ml acetonitrile which has been dried over a molecular sieve 3A. 18.2 ml (0.097 mole) of trimethylsilyl triflate were added within 20 minutes. The yellow solution was stirred for 20 minutes. Subsequently, the solvent was removed in vacuo at 35 °C. The formed foam was dissolved in 300 ml dichloromethane and 4.5 g activated charcoal was added. The suspension was filtered. The filtrate was concentrated. 49.5 g (100 %) of a yellow foam were obtained.

¹ H-NMR (400 MHz, D ₂ 0): 2.02, 2.06, 2.09 (3x s, 3x 3H, COCH ₃ ), 4.45 (m, 2H, H5’), 4.82 (m, 1 H, H4 ^' ), 5.38 (t, 1 H, H3’), 5.49 (dd, 1 H, H2’), 6.51 (d, 1 H, H1’), 8.22 (t, 1 H, H5), 8.92 (d, 1 H, H4), 9.13 (d, 1 H, H6), 9.37 (s, 1 H, H2). Impurities: 3 mol% alpha-anomer, 4 mol% nicotinamide.

¹³ C-NMR (100 MHz, D ₂ 0): 19.8, 19.9, 20.2 (3x COCH ₃ ), 62.6 (C5‘), 69.4 (C3‘), 76.4 (C2‘), 82.7 (C4‘), 97.3 (C1‘); 1 14.9 + 1 18.1 + 121.2 + 124.4 (q, CF3); 128.7 (C5), 134.2 (C3), 140.4 (C2), 143.1 (C6), 146.2 (C4), 165.5 (CONH2), 172.3, 172.4, 173.3 (3x CO).

Example 12b: for comparison

[00265] The method was carried out as described by Tanimori using a high excess of trimethylsilyl triflate, wherein the product was isolated as described in Example 12a. The obtained foam contained a mixture of approx b-anomer : a-anomer : nicotinamide = 2 : 1 : 1 .

Example 13: Preparation of nicotinamide^-D-riboside-2, 3, 5-triacetate L- hydrogen tartrate from nicotinamide^-D-riboside-2, 3, 5-triacetate triflate prepared according to Example 12

[00266] 5.00 g nicotinamide-2, 3, 5-tri-0-acetyl-B-D-ribofuranoside triflate from Example 12 were dissolved in 50 ml ethanol. 1 .42 g L-tartaric acid were added. Subsequently, 1 .31 ml triethylamine were added. The generated emulsion was heated for a short time in order to promote crystallization, and cooled down. The formed precipitate was isolated by filtration and dried in vacuo at 30 °C. 5.07 g (101 .4 %) of a white crystalline powder were obtained (mp 127 °C).

¹ H-NMR (400 MHz, D ₂ 0): 2.08, 2.12, 2.16 (3x s, 3x 3H, COCH ₃ ), 4.43 (s, 2H, 2x CHOH, H-tartrate), 4.52 (m, 2H, H5’), 4.88 (m, 1 H, H4 ^' ), 5.44 (t, 1 H, H3’), 5.56 (dd, 1 H, H2’), 6.58 (d, 1 H, HT), 8.28 (t, 1 H, H5), 8.99 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.43 (s, 1 H, H2). Impurities: < 1 mol% nicotinamide; 0.35 mol% TEA salt: 1 .21 (t, 9H), 3.13 (q, 6H). Solvents: 2 mol% ethanol: 3.57 (q, 2H), 1 .10 (t, 3H).

¹³ C-NMR (100 MHz, D ₂ 0): 19.8, 19.9, 20.2 (3x COCH ₃ ), 62.6 (C5‘), 69.4 (C3‘), 72.8 (2x CHOH, H-tartrate), 76.3 (C2‘), 82.6 (C4‘), 97.3 (C1‘), 128.6 (C5), 134.2 (C3), 140.4 (C2), 143.1 (C6), 146.3 (C4), 165.5 (CONH2), 172.3, 172.4, 173.3 (3x CO), 176.3 (2x COO, H- tartrate). Example 14: Preparation of nicotinamide-8-D-riboside-2, 3, 5-triacetate D- hydrogen tartrate from nicotinamide-8-D-riboside-2, 3, 5-triacetate bromide

[00267] Crystalline nicotinamide-2, 3, 5-0-triacetyl-B-D-riboside D-hydrogen tartrate was prepared according to Example 11a.

[00268] For comparison, the product was prepared according to the method of Example 11b. The amorphous product subjected to crystallization was identical to the product obtained in Example 11a.

[00269] XRD is shown in Fig. 8.

Example 15: Deacylation of nicotinamide-8-D-riboside-2, 3, 5-triacetate L- hydrogen tartrate (from Example 11) exemplifying Pathway 2

Example 15a: Deacylation using sulfuric acid and neutralization using triethylamine

[00270] Preparation of a diluted sulfuric acid in methanol: 27 g methanol were cooled down to 0 °C. 3.00 g sulfuric acid were added while stirring resulting in a 10 % methanolic sulfuric acid.

[00271 ] Deacylation of nicotinamide-B-D-riboside-2, 3, 5-triacetate L-hvdroqen tartrate: 3.00 g nicotinamide-B-D-riboside-2, 3, 5-triacetate L-hydrogen tartrate were suspended in 15 ml methanol while stirring. After addition of 11.7 g of the above methanolic sulfuric acid a yellowish solution was generated. After stirring at room temperature for 5 days, only product and nicotinamide as impurity were present as detected by thin-layer chromatography.

[00272] Conversion to nicotinamide-B-D-riboside L-hvdroqen tartrate after neutralization with triethylamine: 1.1 ml triethylamine were added to the above solution in order to adjust pH to about 3.5. 0.85 g L-tartaric acid were added. After addition of 0.8 ml triethylamine, the product started crystallizing. The suspension was stirred for another hour and was then stored for 12 hours in a refrigerator. The formed crystals were filtered off, washed with isopropanol and were dried in vacuo at 30 °C. 1 .01 g (44.2 %) of a white crystalline powder having a melting point of 126-127 °C were obtained.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.96 (dd, 1 H, H5’), 4.27 (t, 1 H, H3’), 4.37- 4.45 (m, 2H, H4\ H2’), 4.42 (s, 2H, 2x CHOH, H-tartrate), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.52 (s, 1 H, H2). Impurities: 3 mol% nicotinamide: 7.85 (m, 1 H), 8.56 (m, 1 H), 8.77 (d, 1 H), 9.00 (s, 1 H); 3.4 mol% TEA salt: 1.18 (t, 9H), 3.1 1 (q, 6H). Solvents: 1 1.3 mol% methanol: 3.25 (s, 3H).

¹³ C-NMR (100 MHz, D2O): 60.2 (C5‘), 69.7 (C3‘), 72.8 (2x CHOH, H-tartrate), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 176.3 (2x COO, H-tartrate). Impurities: 8.2, 46.6 (TEA salt). Solvents: 48.9 (methanol).

Example 15b: Deacylation using HBr in glacial acetic acid and neutralization using triethylamine

[00273] Deacylation of nicotinamide43>-D-riboside-2, 3, 5-triacetate L-hydrogen tartrate: 3.0 g nicotinamide-B-D-riboside-2, 3, 5-triacetate L-hydrogen tartrate were suspended in 15 ml methanol while stirring. The suspension was cooled down to 5 °C and 3.0 ml HBr 33 % in glacial acetic acid were added. A yellowish solution was generated which was stirred at room temperature for three days. Thin-layer chromatography revealed that deacylation was complete.

[00274] Conversion to nicotinamide-B-D-riboside L-hydrogen tartrate after neutralization with triethylamine: 1 ml triethylamine was added in portions to the above solution. 1 .5 ml water were added wherein a yellow solution was formed. Subsequently, 0.85 g L-tartaric acid were added. After addition of 0.8 ml triethylamine, product started crystallizing. The product suspension was stirred for another hour at room temperature. The formed crystals were filtered off, washed with 7 ml isopropanol and 5 ml acetone and were dried in vacuo at 30 °C. 0.82 g (36 %) of a white crystalline powder having a melting point of 129 to 130 °C were obtained. ¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 15a. Impurities: 1 mol% nicotinamide; 0.1 mol% TEA salt. Solvents: 2.7 mol% methanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 15a.

Example 16: Deacylation of nicotinamide-2, 3, 5-tri-0-acetyl-p-D-ribofuranoside bromide (from Example 1) exemplifying Pathway 3

Example 16a: Deacylation using sulfuric acid and neutralization using triethylamine

[00275] Preparation of a diluted sulfuric acid in methanol: 20 ml methanol were cooled down to 0 °C. 2.00 g of a 96 % sulfuric acid were added while stirring. 21 ml of a 0.93 M methanolic sulfuric acid were obtained.

[00276] Deacylation of nicotinamide-2, 3, 5-tri-0-acetyl-3-D-ribofuranoside bromide: 5.00 g nicotinamide-2, 3, 5-tri-0-acetyl- -D-ribofuranoside bromide were suspended in

24.4 ml methanol while stirring, wherein a part of the educt was dissolved. 5.6 ml of the above methanolic sulfuric acid was added. The resulting colorless solution was stirred at room temperature. The solution was stirred for three days wherein a suspension was generated.

[00277] Conversion to nicotinamide-B-D-riboside L-hvdroqen tartrate after neutralization with triethylamine: 1 .36 ml triethylamine were added to the above suspension. After addition of 3.4 ml water, a colorless solution was generated. 1 .63 g L-tartaric acid were added, wherein product started precipitating. Further product precipitated after addition of further 1 .35 ml triethylamine. The suspension was filtered, the obtained solid was washed with methanol and dried in vacuo at 30 °C.

2.4 g (55 %) of a crystalline white powder were obtained. Mp. 129.5 °C. IC: Residual bromide 0.05 %.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.96 (dd, 1 H, H5’), 4.27 (t, 1 H, H3’), 4.37-4.45 (m, 2H, H4’, H2’), 4.42 (s, 2H, 2x CHOH, H-tartrate), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.52 (s, 1 H, H2). Impurities: 2 mol% nicotinamide: 7.83 (m, 1 H), 8.54 (m, 1 H), 8.76 (d, 1 H), 9.00 (s, 1 H); 0.7 mol% TEA salt: 1.19 (t, 9H), 3.1 1 (q, 6H). Solvents: 7 mol% methanol: 3.25 (s, 3H). ¹³ C-NMR (100 MHz, D ₂ 0): 60.2 (C5‘), 69.7 (C3‘), 72.8 (2x CHOH, H-tartrate), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 176.3 (2x COO, H-tartrate). Solvents: 48.9 (methanol).

Example 16b: Deacylation using HBr in glacial acetic acid and neutralization using triethylamine

[00278] Deacylation of nicotinamide-2, 3, 5-tri-0-acetyl-3-D-ribofuranoside bromide: 5.00 g nicotinamide-2, 3, 5-tri-0-acetyl-p-D-ribofuranoside bromide were dissolved at room temperature in 30 ml methanol while stirring. After addition of 3.75 ml HBr 33 % in glacial acetic acid the formed yellow solution was stirred for three days at room temperature. A white suspension of nicotinamide-p-D-ribofuranoside bromide was generated as controlled by thin-layer chromatography.

[00279] Conversion of nicotinamide-3-D-hbofuranoside bromide to nicotinamide-3-D- ribofuranoside L-hvdroqen tartrate after neutralization using triethylamine: 2.50 ml triethylamine were added in portions to the above suspension. Subsequently, 2.5 ml water were added. 1.63 g L-tartaric acid were added to the formed yellowish solution. Product started precipitating after further addition of 1.52 ml triethylamine at a pH of 3.5 to 4. The crystalline product was filtered off, washed with 10 ml isopropanol and 10 ml acetone and was dried in vacuo at 30 °C. 2.93 g (66.9 %) of a white crystalline powder were obtained. Mp. 127.5 to 128.5 °C. IC: Residual bromide 0.33 %.

1 H-NMR (400 MHz, D ₂ 0): Analogous to Example 15a. Impurities: 1 mol% nicotinamide; 2.3 mol% TEA salt. Solvents: 7 mol% methanol.

13C-NMR (100 MHz, D ₂ 0): Analogous to Example 15a.

Example 16c: Deacylation using triethylamine

[00280] 5.00 g nicotinamide-2, 3, 5-tri-O-acetyl-p-D-ribofuranoside bromide were dissolved at room temperature in 30 ml methanol while stirring. 1.52 ml triethylamine (1 eq) were added. The yellow solution was stirred for 24 hours. Control by thin-layer chromatography showed nearly complete conversion, however also the formation of nicotinamide. 1.63 g L-tartaric acid were added to the formed suspension. Product started precipitating. The product suspension was stirred for one hour at 0 °C, the formed product was isolated by titration, washed with 12 ml isopropanol and 12 ml acetone and was dried in vacuo at 30 °C. 1.86 g (42.4 %) of a white powder were obtained. Mp. 127 °C; IC: Residual bromide 0.26 %.

1 H-NMR (400 MHz, D ₂ 0): Analogous to Example 15a. Impurities: 6 mol% nicotinamide; 1.7 mol% TEA salt. Solvents: 18 mol% methanol, 0.5 mol% isopropanol.

13C-NMR (100 MHz, D20): Analogous to Example 15a.

[00281 ] Example 16d: Deacylation using triethylamine at 0-5 °C

[00282] Example 16c was repeated with the difference that nicotinamide-2, 3, 5-tri-O- acetyl- -D-ribofuranoside bromide was subjected to triethylamine at 0 °C. Yield was increased to 85.8 %.

Example 17: Preparation of nicotinamide-6-D-riboside-2, 3, 5-triacetate L- hydrogen tartrate obtained by separation of the L-hydrogen tartrate salt from a mixture of b- and a-anomers generated by glycosylation of nicotinamide with 1- bromo-2,3,5-triacetyl-D-ribofuranoside exemplifying Pathway 4

[00283] To 100 ml of a crude mixture of anomers (obtained analogously to Example 1 ), which theoretically contained 54 mmol nicotinamide-D-ribofuranoside-2, 3,5- triacetate, 1 1.7 ml triethylamine were added, wherein the contained acids (HBr and acetic acid) were partially neutralized. 5.16 g L-tartaric acid were added to the orange-yellow solution while stirring. As soon as the tartaric acid was completely dissolved, 4.8 ml triethylamine were added.

[00284] The solution was concentrated by distilling 42 ml thereof off, wherein needles of triethylamine hydrobromide started precipitating. 30 ml isopropanol were added and the suspension was cooled down to 0 °C while stirring. The suspension was filtered and the residue (triethylamine hydrobromide) was washed with 14 ml isopropanol.

[00285] The filtrate was seeded with some crystals of product. Subsequently, 30 ml tert-butyl-methylether were slowly added, wherein product started precipitating. The product was stored for 12 hours in the refrigerator. After filtration, washing twice with 25 ml isopropanol, respectively, the solid was dried at 35 °C in vacuo. 13.86 g (48.5 %) of nicotinamide43 _> -D-riboside-2, 3, 5-triacetate L-hydrogen tartrate in the form of white crystal were obtained. Mp. 123-124 °C; IC: Residual bromide 2.64 %.

¹ H-NMR (400 MHz, D ₂ 0): 2.08, 2.12, 2.15 (3x s, 3x 3H, COCH ₃ ), 4.43 (s, 2H, 2x CHOH, H-tartrate), 4.52 (m, 2H, H5’), 4.88 (m, 1 H, H4 ^' ), 5.44 (t, 1 H, H3’), 5.56 (dd, 1 H, H2’), 6.58 (d, 1 H, H1’), 8.27 (t, 1 H, H5), 8.99 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.43 (s, 1 H, H2). Impurities: < 1 mol% nicotinamide; 20 mol% TEA salt: 1.21 (t, 9H), 3.13 (q, 6H). Solvents: 2.2 mol% isopropanol: 1.09 (d, 6H), 3.93 (m, 1 H).

¹³ C-NMR (100 MHz, D2O): 19.8, 19.9, 20.2 (3x COCH ₃ ), 62.6 (C5‘), 69.4 (C3‘), 72.8 (2x CHOH, H-tartrate), 76.3 (C2‘), 82.6 (C4‘), 97.3 (C1‘), 128.6 (C5), 134.2 (C3), 140.4 (C2), 143.1 (C6), 146.2 (C4), 165.5 (CONH2), 172.3, 172.4, 173.3 (3x CO), 176.3 (2x COO, H- tartrate). Impurity: TEA salt: 8.2, 46.7.

Example 18: Deacylation of a mixture of anomers of nicotinamide-a^l-D-riboside- 2, 3, 5-triacetate bromide exemplifying Pathway 5

[00286] 100 ml of a crude solution containing the anomers (see Example 1), which theoretically contains about 54 mmol nicotinamide-D-ribofuranoside-2, 3, 5-triacetate bromide was completely concentrated at a temperature in the range of from 35 - 40 °C by using a rotary evaporator. The resulting yellow viscous oil was diluted with 44 ml methanol. Subsequently, 10 ml HBr 33 % in glacial acetic acid were added. The yellowish clear solution was stirred at room temperature. After one day, nicotinamide- b-D-riboside bromide precipitated. After 5 days, complete deacylation was achieved as controlled by thin-layer chromatography.

[00287] Separation as nicotinamide-B-D-riboside L-hydrogen tartrate: 7.5 ml triethylamine were added to the above suspension in order to neutralize HBr and acetic acid. After addition of 4 ml water a clear solution was obtained. 8.6 g tartaric acid were added to the yellowish solution which was filtered in order to remove insoluble precipitates. Subsequently, 5.4 ml triethylamine were added, wherein the desired product started precipitating. After filtration and washing with ethanol and methanol, the obtained solid was dried in vacuo at 30 °C. 7.27g (33.3 %) of a white crystalline powder were obtained. Mp. 128.5 - 129.5 °C; IC: residual bromide 0.16 %. ¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 15a. Impurities: 3 mol% nicotinamide; 1.2 mol% TEA salt. Solvents: 7 mol% methanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 15a.

Example 19: Deacylation of nicotinamide^-D-riboside-2, 3, 5-triacetate triflate exemplifying Pathway 5

[00288] Example 19a: Deacylation using sulfuric acid and neutralization using triethylamine

[00289] Preparation of a diluted sulfuric acid in methanol: 27 g methanol were cooled down to 0 °C. 3.00 g of a 96 % sulfuric acid were added while stirring. 30 g of a 10 % methanolic sulfuric acid were obtained.

[00290] Deacylation of nicotinamide-2, 3, 5-tri-0-acetyl-3-D-ribofuranoside triflate: 3.00 g nicotinamide-2, 3, 5-tri-0-acetyl- -D-ribofuranoside triflate were dissolved in 15 ml methanol while stirring. 5.86 g of the above methanolic sulfuric acid were added. The resulting colorless solution was stirred at room temperature. The solution was stirred for three days. Control by thin-layer chromatography revealed complete deacylation and some nicotinamide impurities.

[00291 ] Conversion to nicotinamide-B-D-riboside L-hvdroqen tartrate after neutralization with triethylamine: 1 .1 ml triethylamine were added to the above solution. 3.3 ml of a 1 .7 molar methanolic solution of triethylammonium L-hydrogen tartrate were added, wherein product immediately started precipitating. Subsequently, 0.40 g L-tartaric acid were added. The product suspension was stored for 12 hours in a refrigerator. After filtration, the obtained solid was washed with methanol and ethanol and dried in vacuo at 30 °C. 1 .23 g (53.8 %) of a white crystalline powder were obtained. Mp. 127 to 128 °C.

¹ H-NMR (400 MHz, D ₂ 0): 3.82 (dd, 1 H, H5’), 3.96 (dd, 1 H, H5’), 4.27 (t, 1 H, H3’), 4.37-4.45 (m, 2H, H4\ H2’), 4.41 (s, 2H, 2x CHOH, H-tartrate), 6.17 (d, 1 H, H1’), 8.20 (t, 1 H, H5), 8.90 (d, 1 H, H4), 9.19 (d, 1 H, H6), 9.51 (s, 1 H, H2). Impurities: 2 mol% nicotinamide: 7.83 (m, 1 H), 8.54 (m, 1 H), 8.76 (d, 1 H), 9.00 (s, 1 H); 2.9 mol% TEA salt: 1 .19 (t, 9H), 3.1 1 (q, 6H). Solvents: 16 mol% methanol: 3.25 (s, 3H), 2 mol% ethanol.

¹³ C-NMR (100 MHz, D ₂ 0): 60.2 (C5‘), 69.7 (C3‘), 72.8 (2x CHOH, H-tartrate), 77.4 (C2‘), 87.6 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 176.3 (2x COO, H-tartrate). Impurities: 8.2, 46.6 (TEA salt). Solvents: 48.9 (methanol).

Example 19b: Deacylation using HBr in glacial acetic acid and neutralization using triethylamine

[00292] 8.00 g nicotinamide-2, 3, 5-tri-0-acetyl-p-D-ribofuranoside triflate were dissolved in 32 ml methanol while stirring. The solution was cooled down to 0-5 °C. After addition of 5.2 ml HBr 33% in glacial acetic acid, the solution was kept stirring at room temperature. According to control by thin-layer chromatography, the product was deacylated after two days.

[00293] The solution was divided into two halves.

[00294] Isolation of the formed intermediate bromide: One half of the solution (20.5 ml) was seeded with nicotinamide-B-D-ribofuranoside bromide and was stirred at room temperature. After about 30 minutes a suspension was formed. The suspension was filtered and the residue was washed with methanol and ethanol and was subsequently dried in vacuo at 30 °C. 0.62 g (24.5 %) of a white crystalline powder were obtained.

¹ H-NMR (400 MHz, D ₂ 0): 3.83 (dd, 1 H, H5’), 3.98 (dd, 1 H, H5’), 4.29 (t, 1 H, H3’), 4.39- 4.48 (m, 2H, H4\ H2’), 6.18 (d, 1 H, H1’), 8.22 (t, 1 H, H5), 8.92 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.52 (s, 1 H, H2).

¹³ C-NMR (100 MHz, D ₂ 0): 60.2 (C5‘), 69.7 (C3‘), 77.4 (C2‘), 87.7 (C4‘), 99.9 (C1‘), 128.5 (C5), 134.0 (C3), 140.4 (C2), 142.7 (C6), 145.7 (C4), 165.8 (CONH2).

[00295] Conversion to nicotinamide-B-D-riboside L-hvdroqen tartrate after neutralization with triethylamine: 1 .8 ml triethylamine were added to the other half of the solution, wherein HBr and acetic acid were partially neutralized. 4.4 ml of a 1 .7 molar methanolic solution of triethylammonium L-hydrogen tartrate were added to the yellowish solution, wherein product started precipitating. After filtration and washing with methanol and ethanol and drying in vacuo at 30 °C, 1.62 g (53.2 %) of a white crystalline powder was obtained. Mp. 127 - 128 °C.

¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 19a. Impurities: 1 mol% nicotinamide; 3.7 mol% TEA salt. Solvents: 12.5 mol% methanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 19a.

Example 19c: Deacylation using triethylamine

[00296] Deacylation of nicotinamide-D-riboside-2, 3, 5-triacetate triflate: 3.00 g of the triflate were dissolved in 18 ml methanol while stirring. 0.8 ml triethylamine (1 eq) were added to the solution cooled down to 0 °C. After stirring for 4 days at 0-5 °C, thin-layer control showed complete conversion.

[00297] Conversion to nicotinamide-B-D-riboside L-hydrogen tartrate: The brown- orange solution obtained in the step above was warmed to room temperature. Subsequently, 0.86 g L-tartaric acid were added. Product started precipitating. The product suspension was cooled down to 0 °C and stirred. After storage in a refrigerator for 12 hours, the suspension was filtered , the obtained solid washed with 5 ml isopropanol and dried in vacuo at 30 °C. 1.44 g (63.0 %) of a brown-yellowish crystalline powder were obtained. Mp. 127 °C.

¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 19a. Impurities: 2 mol% nicotinamide; 1.9 mol% TEA salt. Solvents: 13.3 mol% methanol, 4 mol% isopropanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 19a.

[00298] Since one equivalent of triethylamine is necessary for deacylation in the above sequence, it can be concluded that triethylamine surprisingly is catalytically active.

Example 19d: Deacylation using HBr in glacial acetic acid, neutralization using tributylamine [00299] Deacylation of nicotinamide-2, 3, 5-tri-O-acetyl-D-ribofuranoside triflate: 2.00 g of the triflate were dissolved in 8 ml methanol while stirring. The solution was cooled down to 0-5 °C. After addition of 1.3 ml HBr 33 % in glacial acetic acid, the green- yellowish solution was stirred at room temperature. After two days no educt could be determined in the solution by thin-layer chromatography.

[00300] Conversion to nicotinamide-3-D-hbofuranoside L-hvdroqen malate after neutralization with tributylamine: 1.3 ml tributylamine were added to the above solution. After addition of 0.6 ml water, any precipitated material was completely dissolved. 0.51 g L-malic acid was added to the brown-yellowish solution. After addition of further 0.9 ml tributylamine product started crystallizing. Formed product was filtered off, washed with methanol and dried in vacuo at 30 °C. 0.48 g (33 %) nicotinamide-p-D-ribofuranoside L- hydrogen malate were obtained. Mp. 1 15.5 - 1 16.5 °C.

¹ H-NMR (400 MHz, D ₂ 0): 2.55 (dd, 1 H, CH ₂ , H-malate), 2.73 (dd, 1 H, CH ₂ , H-malate), 3.83 (dd, 1 H, H5’), 3.98 (dd, 1 H, H5’), 4.28 (t, 1 H, H3’), 4.29 (dd, 1 H, CHOH, H-malate), 4.39-4.46 (m, 2H, H4\ H2’), 6.18 (d, 1 H, H1’), 8.21 (t, 1 H, H5), 8.91 (d, 1 H, H4), 9.20 (d, 1 H, H6), 9.53 (s, 1 H, H2). Impurities: < 1 mol% nicotinamide; 0.35 mol% TBA salt: 0.85 (t, 9H), 1.29 (m, 6H), 1.59 (m, 6H), 3.05 (q, 6H). Solvents: 2.3 mol% methanol: 3.27 (s, 3H).

¹³ C-NMR (100 MHz, D ₂ 0): 40.0 (CH ₂ , H-malate), 60.2 (C5‘), 68.5 (CHOH, H-malate), 69.8 (C3‘), 77.4 (C2‘), 87.7 (C4‘), 99.9 (C1‘), 128.4 (C5), 133.9 (C3), 140.4 (C2), 142.6 (C6), 145.6 (C4), 165.8 (CONH2), 176.3 (COO, H-malate), 179.0 (COO, H-malate).

Example 20: Preparation of nicotinamide-2, 3, 5-tri-0-acetyl-ft-D-ribofuranoside iodide

[00301 ] 6.00 g (0.049 mole) of nicotinamide and 14.9 g (0.047 mole) of b-D- ribofuranose 1 ,2,3,5-tetraacetate were suspended upon stirring at room temperature in 190 ml acetonitrile which has been dried over a molecular sieve 3A. The suspension was warmed to 35°C while most of the solids dissolved. 6.9 ml (0.048 mole) of trimethylsilyl iodide were added within 20 minutes and the yellow suspension was stirred for a further two hours at 35°C. Subsequently, the internal temperature was kept at 40°C and 45°C for one hour each. The solvent was removed in vacuo at 35 °C. The formed foam was dissolved in 100 ml dichloromethane and 1.2 g activated charcoal was added. The suspension was filtered. The filtrate was concentrated. 22 g (93 %) of a deep yellow foam were obtained.

¹ H-NMR (400 MHz, D ₂ 0): 2.05, 2.07, 2.12 (3x s, 3x 3H, COCH ₃ ), 4.46 (m, 2H, H5’), 4.84 (m, 1 H, H4 ^' ), 5.41 (t, 1 H, H3’), 5.53 (dd, 1 H, H2’), 6.58 (d, 1 H, H1’), 8.28 (t, 1 H, H5), 8.94 (d, 1 H, H4), 9.18 (d, 1 H, H6), 9.38 (s, 1 H, H2). Impurities: 15 mol% alpha-anomer, 3 mol% nicotinamide.

¹³ C-NMR (100 MHz, D2O): 20.0, 20.1 , 20.4 (3x COCH ₃ ), 62.6 (C5‘), 69.3 (C3‘), 76.1 (C2‘), 82.5 (C4‘), 97.2 (C1‘), 128.8 (C5), 134.1 (C3), 140.4 (C2), 143.1 (C6), 146.2 (C4), 165.1 (CONH2), 172.0, 172.1 , 173.0 (3x CO).

Example 21 : Deacylation of nicotinamide^-D-riboside-2, 3, 5-triacetate iodide exemplifying Pathway 5

[00302] Deacylation using sulfuric acid and neutralization using triethylamine

[00303] Preparation of a diluted sulfuric acid in methanol: 10 ml methanol were cooled down to 0°C. 1.20 ml of a 96 % sulfuric acid were added while stirring. The methanolic sulfuric acid was used in the deacetylation below.

[00304] Deacylation of nicotinamide-2, 3, 5-tri-0-acetyl-3-D-ribofuranoside iodide: 1 1.0 g nicotinamide-2, 3, 5-tri-0-acetyl- -D-ribofuranoside iodide were dissolved in 33 ml methanol while stirring. The above prepared methanolic sulfuric acid was added. The resulting orange-brown solution was stirred at room temperature for one day. Control by thin-layer chromatography revealed complete deacylation and some impurities. 3.5 ml triethylamine were added.

[00305] The solution was divided into two halves.

[00306] Conversion to nicotinamide-B-D-riboside L-hvdroqen tartrate after neutralization with triethylamine: To one half of the above solution 1.65 g L-tartaric acid were added, followed by further 1.6 ml triethylamine. Product started precipitating almost immediately. The product suspension was stirred one hour at ambient temperature, two hours in an ice-bath and stored for 12 hours in a refrigerator. After filtration, the obtained solid was washed with methanol and dried in vacuo at 30°C. 2.10 g (48 %) of an almost white crystalline powder of nicotinamide-p-D-ribofuranoside L-hydrogen tartrate were obtained. Mp. 125.5 - 126°C.

¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 19a. Impurities: 1 mol% nicotinamide; 3.8 mol% TEA salt. Solvents: 18.2 mol% methanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 19a.

[00307] Conversion to nicotinamide-B-D-riboside L-hydrogen malate after neutralization with triethylamine: 1.45 g L-malic acid were added to the other half of the above solution, followed by further 1.1 ml triethylamine. The solution was seeded. Product started precipitating a few minutes later. The product suspension was stirred one hour at ambient temperature and two hours in an ice-bath, then stored for 12 hours in a refrigerator. After filtration, the obtained solid was washed with methanol and ethanol and dried in vacuo at 30°C. 1.37 g (32.7 %) nicotinamide-p-D-ribofuranoside L-hydrogen malate were obtained as an almost white crystalline solid. Mp. 1 14 - 115°C.

¹ H-NMR (400 MHz, D ₂ 0): Analogous to Example 19d. Impurities: 0.5 mol% nicotinamide; 0.5 mol% TEA salt. Solvents: 2.4 mol% methanol, 0.4 mol% ethanol.

¹³ C-NMR (100 MHz, D ₂ 0): Analogous to Example 19d.