FIELD OF THE INVENTION

The present invention relates to O-GlcNAc hydrolase (OGA) inhibitors, having the structure shown in Formula (I) wherein the radicals are as defined in the specification. The invention is also directed to pharmaceutical compositions comprising such compounds, to processes for preparing such compounds and compositions, and to the use of such compounds and compositions for the prevention and treatment of disorders in which inhibition of OGA is beneficial, such as tauopathies, in particular Alzheimer’s disease or progressive supranuclear palsy; and neurodegenerative diseases accompanied by a tau pathology, in particular amyotrophic lateral sclerosis or frontotemporal lobe dementia caused by C90RF72 mutations; or alpha synucleinopathies, in particular Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease.

BACKGROUND OF THE INVENTION

O-GlcNAcylation is a reversible modification of proteins where N-acetyl-D- glucosamine residues are transferred to the hydroxyl groups of serine- and threonine residues yield O-GlcNAcylated proteins. More than 1000 of such target proteins have been identified both in the cytosol and nucleus of eukaryotes. The modification is thought to regulate a huge spectrum of cellular processes including transcription, cytoskeletal processes, cell cycle, proteasomal degradation, and receptor signalling.

O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (OGA) are the only two proteins described that add (OGT) or remove (OGA) O-GlcNAc from target proteins. OGA was initially purified in 1994 from spleen preparation and 1998 identified as antigen expressed by meningiomas and termed MGEA5, consists of 916 amino (102915 Dalton) as a monomer in the cytosolic compartment of cells. It is to be distinguished from ER- and Golgi-related glycosylation processes that are important for trafficking and secretion of proteins and different to OGA have an acidic pH optimum, whereas OGA display highest activity at neutral pH.

The OGA catalytic domain with its double aspartate catalytic center resides in the N- terminal part of the enzyme which is flanked by two flexible domains. The C-terminal part consists of a putative HAT (histone acetyl transferase domain) preceded by a stalk domain. It has yet still to be proven that the HAT-domain is catalytically active.

O-GlcNAcylated proteins as well as OGT and OGA themselves are particularly abundant in the brain and neurons suggesting this modification plays an important role in the central nervous system. Indeed, studies confirmed that G-GlcN Acylation represents a key regulatory mechanism contributing to neuronal communication, memory formation and neurodegenerative disease. Moreover, it has been shown that OGT is essential for embryogenesis in several animal models and ogt null mice are embryonic lethal. OGA is also indispensible for mammalian development. Two independent studies have shown that OGA homozygous null mice do not survive beyond 24-48 hours after birth. Oga deletion has led to defects in glycogen mobilization in pups and it caused genomic instability linked cell cycle arrest in MEFs derived from homozygous knockout embryos. The heterozygous animals survived to adulthood however they exhibited alterations in both transcription and metabolism.

It is known that perturbations in O-GlcNAc cycling impact chronic metabolic diseases such as diabetes, as well as cancer. Oga heterozygosity suppressed intestinal tumorigenesis in an Ape- mouse cancer model and the Oga gene ( MGEA5 ) is a documented human diabetes susceptibility locus.

In addition, O-GlcNAc-modifications have been identified on several proteins that are involved in the development and progression of neurodegenerative diseases and a correlation between variations of O-GlcNAc levels on the formation of neurofibrillary tangle (NFT) protein by Tau in Alzheimer’s disease has been suggested. In addition, O-GlcNAcylation of alpha-synuclein in Parkinson’s disease has been described (Levine, PM, et al. PNAS January 29, 2019, Vol. 116, No. 5, pp 1511-1519; Lewis, YE et al. ACS Chem Biol. 2017 Apr 21, Vol. 2, No. 4, pp 1020-1027; Marotta, NP et al.

Nat Chem. 2015 Nov, Vol. No. 11, pp. 913-20).

In the central nervous system six splice variants of tau have been described. Tau is encoded on chromosome 17 and consists in its longest splice variant expressed in the central nervous system of 441 amino acids. These isoforms differ by two N-terminal inserts (exon 2 and 3) and exon 10 which lie within the microtubule binding domain. Exon 10 is of considerable interest in tauopathies as it harbours multiple mutations that render tau prone to aggregation as described below. Tau protein binds to and stabilizes the neuronal microtubule cytoskeleton which is important for regulation of the intracellular transport of organelles along the axonal compartments. Thus, tau plays an important role in the formation of axons and maintenance of their integrity. In addition, a role in the physiology of dendritic spines has been suggested as well.

Tau aggregation is either one of the underlying causes for a variety of so called tauopathies like PSP (progressive supranuclear palsy), Down’s syndrome (DS), FTLD (frontotemporal lobe dementia), FTDP-17 (frontotemporal dementia with Parkinsonism- 17), Pick’s disease (PD), CBD (corticobasal degeneration), agryophilic grain disease (AGD), and AD (Alzheimer’s disease). In addition, tau pathology accompanies additional neurodegenerative diseases like amyotrophic lateral sclerosis (ALS) or FTLD cause by C90RF72 mutations. In these diseases, tau is post- translationally modified by excessive phosphorylation which is thought to detach tau from microtubules and makes it prone to aggregation. O-GlcNAcylation of tau regulates the extent of phosphorylation as serine or threonine residues carrying O- GlcNAc-residues are not amenable to phosphorylation. This effectively renders tau less prone to detaching from microtubules and reduces aggregation into neurotoxic tangles which ultimately lead to neurotoxicity and neuronal cell death. This mechanism may also reduce the cell-to-cell spreading of tau-aggregates released by neurons via along interconnected circuits in the brain which has recently been discussed to accelerate pathology in tau-related dementias. Indeed, hyperphosphorylated tau isolated from brains of AD-patients showed significantly reduced O-GlcNAcylation levels.

An OGA inhibitor administered to JNPL3 tau transgenic mice successfully reduced NFT formation and neuronal loss without apparent adverse effects. This observation has been confirmed in another rodent model of tauopathy where the expression of mutant tau found in FTD can be induced (tg4510). Dosing of a small molecule inhibitor of OGA was efficacious in reducing the formation of tau-aggregation and attenuated the cortical atrophy and ventricle enlargement. Moreover, the O-GlcNAcylation of the amyloid precursor protein (APP) favours processing via the non-amyloidogenic route to produce soluble APP fragment and avoid cleavage that results in the AD associated amyloid-beta (Ab) formation.

Maintaining O-GlcNAcylation of tau by inhibition of OGA represents a potential approach to decrease tau-phosphorylation and tau-aggregation in neurodegenerative diseases mentioned above thereby attenuating or stopping the progression of neurodegenerative tauopathy-diseases.

WO2012/117219 (Summit Corp. pic., published 7 September 2012) describes N-[[5- (hydroxymethyl)pyrrolidin-2-yl]methyl]alkylamide and N-alkyl-2-[5- (hydroxymethyl)pyrrolidin-2-yl]acetamide derivatives as OGA inhibitors.

WO2014/159234 (Merck Patent GMBH, published 2 October 2014) discloses mainly 4-phenyl or benzyl-piperidine and piperazine compounds substituted at the 1 -position with an acetamido-thiazolylmethyl or acetamidoxazolylmethyl substituent and the compound N-[5-[(3-phenyl-l-piperidyl)methyl]thiazol-2-yl]acetamide;

WO20 16/0300443 (Asceneuron S.A., published 3 March 2016), WO2017/144633 and W02017/0114639 (Asceneuron S.A., published 31 August 2017) disclose 1,4- disubstituted piperidines or piperazines as OGA inhibitors;

WO2017/144637 (Asceneuron S.A, published 31 August 2017) discloses more particular 4-substituted l-[l-(l,3-benzodioxol-5-yl)ethyl]-piperazine; l-[l-(2,3- dihydrobenzofuran-5-yl)ethyl]-; l-[l-(2,3-dihydrobenzofuran-6-yl)ethyl]-; and 1-[1- (2,3-dihydro-l,4-benzodioxin-6-yl)ethyl]-piperazine derivatives as OGA inhibitors;

WO2017/106254 (Merck Sharp & Dohme Corp.) describes substituted N-[5-[(4- methylene-l-piperidyl)methyl]thiazol-2-yl]acetamide; WO2018/217558 (Eli Lilly and Company) describes 5-methyl-l,3,4-oxadiazol-2-yl and WO2019/178191 (Biogen Ma Inc) discloses [(hetero)aryl-3-ylmethyl]pyrrolidin-l-ylmethyl- and [(hetero)aryl-3- ylmethyl]piperidin-l-ylmethyl- derivative compounds as OGA inhibitors; and WO2018/140299 (Eli Lilly and Company) discloses N-[fluoro-5-[[(2S,4S)-2-methyl-4- [(5-methyl-l,2,4-oxadiazol-3-yl)methoxy[-l-piperidyl]methyl] thiazol-2-yl]acetamide as OGA inhibitor.

There is still a need for OGA inhibitor compounds with an advantageous balance of properties, for example with improved potency, good bioavailability, pharmacokinetics, and brain penetration, and/or better toxicity profile. It is accordingly an object of the present invention to provide compounds that overcome at least some of these problems.

SUMMARY OF THE INVENTION

The present invention is directed to compounds of Formula (I) and the tautomers and the stereoisomeric forms thereof, wherein R ^A is selected from the group consisting of a) a six-membered monocyclic heteroaryl radical selected from the group consisting of pyridyl, pyrimidinyl, pyridazinyl, and pyrazinyl; b) a five-membered monocyclic heteroaryl radical selected from the group consisting of thienyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, thiadiazolyl, and oxadiazolyl; and c) a 9- to 10-membered bicyclic heteroaryl radical selected from the group consisting of 1,8-naphthyridinyl, pyrazolo[l,5-a]pyridinyl, imidazo[l,5-a]pyridinyl, imidazo[l,5- bjpyridazinyl, indolizinyl, lH-indolyl, lH-indazolyl, quinolinyl, isoquinolinyl, thiazolo [4, 5 -bjpyridinyl ; wherein each of a), b) or c) may be optionally substituted with 1, 2 or 3 substituents each independently selected from the group consisting of halo; cyano; hydroxy; phenyl; Ci-4alkyl optionally substituted with 1, 2, or 3 independently selected halo substituents; and Ci-4alkyloxy optionally substituted with 1, 2, or 3 independently selected halo substituents;

L ^A is selected from the group consisting of -0-, -OCH2-, and -CH2O-; a and b represent the carbon atom through which -L ^A -R ^A is attached to the piperidine core; R ^la , R ^lb , R ^2a and R ^2b are each independently selected from the group consisting of hydrogen and Ci-3alkyl, in particular methyl; with the proviso that at least one of R ^la , R ^lb , R ^2a and R ^2b is Ci-3alkyl, in particular methyl;

R is H or C¾; and

R ^B is a bicyclic radical of formula (b-1), (b-2) or (b-3)

(b-1) (b-2) (b-3) wherein the dashed line represents an optional double bond; and

R ³ , R ⁴ and R ⁵ are each independently selected from the group consisting of hydrogen and fluoro; and the pharmaceutically acceptable salts and the solvates thereof.

Illustrative of the invention is a pharmaceutical composition comprising a pharmaceutically acceptable carrier and any of the compounds described above. An illustration of the invention is a pharmaceutical composition made by mixing any of the compounds described above and a pharmaceutically acceptable carrier. Illustrating the invention is a process for making a pharmaceutical composition comprising mixing any of the compounds described above and a pharmaceutically acceptable carrier.

Exemplifying the invention are methods of preventing or treating a disorder mediated by the inhibition of O-GlcNAc hydrolase (OGA), comprising administering to a subject in need thereof a therapeutically effective amount of any of the compounds or pharmaceutical compositions described above.

Further exemplifying the invention are methods of inhibiting OGA, comprising administering to a subject in need thereof a prophylactically or a therapeutically effective amount of any of the compounds or pharmaceutical compositions described above.

An example of the invention is a method of preventing or treating a disorder selected from a tauopathy, in particular a tauopathy selected from the group consisting of Alzheimer’s disease, progressive supranuclear palsy, Down’s syndrome, frontotemporal lobe dementia, frontotemporal dementia with Parkinsonism- 17, Pick’s disease, corticobasal degeneration, and agryophilic grain disease; or a neurodegenerative disease accompanied by a tau pathology, in particular a neurodegenerative disease selected from amyotrophic lateral sclerosis or frontotemporal lobe dementia caused by C90RF72 mutations, or preventing or treating a disorder selected from an alpha synucleinopathy, in particular Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease, comprising administering to a subject in need thereof, a prophylactically or a therapeutically effective amount of any of the compounds or pharmaceutical compositions described above.

Another example of the invention is any of the compounds described above for use in preventing or treating a tauopathy, in particular a tauopathy selected from the group consisting of Alzheimer’s disease, progressive supranuclear palsy, Down’s syndrome, frontotemporal lobe dementia, frontotemporal dementia with Parkinsonism- 17, Pick’s disease, corticobasal degeneration, and agryophilic grain disease; or a neurodegenerative disease accompanied by a tau pathology, in particular a neurodegenerative disease selected from amyotrophic lateral sclerosis or frontotemporal lobe dementia caused by C90RF72 mutations or for use in preventing or treating a disorder selected from an alpha synucleinopathy, in particular Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease,, in a subject in need thereof.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compounds of Formula (I), as defined herein before, and pharmaceutically acceptable addition salts and solvates thereof. The compounds of Formula (I) are inhibitors of O-GlcNAc hydrolase (OGA) and may be useful in the prevention or treatment of tauopathies, in particular a tauopathy selected from the group consisting of Alzheimer’s disease, progressive supranuclear palsy, Down’s syndrome, frontotemporal lobe dementia, frontotemporal dementia with Parkinsonism- 17, Pick’s disease, corticobasal degeneration, and agryophilic grain disease; or maybe useful in the prevention or treatment of neurodegenerative diseases accompanied by a tau pathology, in particular a neurodegenerative disease selected from amyotrophic lateral sclerosis or frontotemporal lobe dementia caused by C90RF72 mutations; or may be useful in the prevention or treatment of alpha synucleinopathies, in particular Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease.

In a particular embodiment, the invention is directed to compounds of Formula (I) as referred to herein, and the tautomers and the stereoisomeric forms thereof, wherein

R ^A is selected from the group consisting of a) a six-membered monocyclic heteroaryl radical selected from the group consisting of pyridyl, pyrimidinyl, pyridazinyl, and pyrazinyl; and b) a five-membered monocyclic heteroaryl radical selected from the group consisting of thienyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, thiadiazolyl, and oxadiazolyl; wherein each of a) or b) may be optionally substituted with 1, 2 or 3 substituents each independently selected from the group consisting of halo; cyano; hydroxy; phenyl; Ci- 4alkyl optionally substituted with 1, 2, or 3 independently selected halo substituents; and Ci-4alkyloxy optionally substituted with 1, 2, or 3 independently selected halo substituents. In a further embodiment, the invention is directed to compounds of Formula (I) as referred to herein, and the tautomers and the stereoisomeric forms thereof, wherein

R ^A is selected from the group consisting of a) a six-membered monocyclic heteroaryl radical selected from the group consisting of pyridyl, pyrimidinyl, pyridazinyl, and pyrazinyl; and b) a five-membered monocyclic heteroaryl radical selected from the group consisting of thienyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, thiadiazolyl, and oxadiazolyl; wherein each of a) or b) may be optionally substituted with 1, 2 or 3 substituents each independently selected from the group consisting of halo; cyano; Ci-4alkyl optionally substituted with 1, 2, or 3 independently selected halo substituents; and Ci-4alkyloxy optionally substituted with 1, 2, or 3 independently selected halo substituents.

In a further embodiment, the invention is directed to compounds of Formula (I) as referred to herein, and the tautomers and the stereoisomeric forms thereof, wherein R ^A is selected from the group consisting of pyridyl, pyrimidinyl, and oxadiazolyl; each of which may be optionally substituted with 1, 2 or 3 substituents, in particular 1 or 2 substituents, each independently selected from the group consisting of halo; cyano; Ci- 4alkyl optionally substituted with 1, 2, or 3 independently selected halo substituents; and Ci-4alkyloxy optionally substituted with 1, 2, or 3 independently selected halo substituents.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein L ^A is -0-. In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein L ^A is -OCH2-. In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein L ^A is -CH2O-.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein

R ^la , R ^lb , R ^2a and R ^2b are each independently selected from the group consisting of hydrogen and methyl; with the proviso that at least one of R ^la , R ^lb , R ^2a and R ^2b is methyl; more in particular, wherein 1 or 2 of R ^la , R ^lb , R ^2a and R ^2b is methyl.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein R ^la is methyl, and R ^lb , R ^2a and R ^2b are each hydrogen.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein R ^la and R ^lb are methyl, and R ^2a and R ^2b are hydrogen.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein R ^2a is methyl, and R ^lb , R ^2a and R ^2b are hydrogen.

In a further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein

R ^B is a bicyclic radical of formula (b-1), (b-2) or (b-3)

(b-1) (b-2) (b-3), wherein R ³ , R ⁴ and R ⁵ are as described herein.

In a yet further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein

R ^B is a bicyclic radical of formula (b-1) or (b-2)

(b-1) (b-2), wherein R ³ , R ⁴ and R ⁵ are as described herein.

In a yet further embodiment, the invention is directed to compounds of Formula (I) as described herein, wherein R ^A is pyridyl, optionally substituted with 1 or 2 substituents, each independently selected from Ci-4alkyl and Ci-4alkyloxy;

L ^A is selected from the group consisting of -0-, -OCH2-, and -CH2O-; a and b represent the carbon atom through which -L ^A -R ^A is attached to the piperidine core; R ^la is methyl and R ^lb , R ^2a and R ^2b are hydrogen; or R ^2a is methyl and R ^la , R ^lb and R ^2b are hydrogen;

R is H or CFF; and

R ^B is selected from In a yet further embodiment, the invention is directed to compounds of Formula (I) as described herein, having the Formula (I- A) wherein all variables are as described herein.

In a yet further embodiment, the invention is directed to compounds of Formula (I) as described herein, having the Formula (I-B) wherein all variables are as described herein.

DEFINITIONS

“Halo” shall denote fluoro, chloro and bromo; “Ci^alkyl” shall denote a straight or branched saturated alkyl group having 1, 2, 3 or 4 carbon atoms, respectively e.g. methyl, ethyl, 1 -propyl, 2-propyl, butyl, 1 -methyl-propyl, 2-methyl- 1 -propyl, 1,1-dimethylethyl, and the like; “Ci-4alkyloxy” shall denote an ether radical wherein Ci-4alkyl is as defined before. When reference is made to L ^A , the definition is to be read from left to right, with the left part of the linker bound to R ^A and the right part of the linker bound to the pyrrolidinediyl or piperidinediyl ring. Thus, when L ^A is, for example, -O-CH2-, then R ^A -L ^A - is R ^A -0-CH ₂ -.

In general, whenever the term “substituted” is used in the present invention, it is meant, unless otherwise indicated or is clear from the context, to indicate that one or more hydrogens, in particular 1 to 3 hydrogens, preferably 1 or 2 hydrogens, more preferably 1 hydrogen, on the atom or radical indicated in the expression using “substituted” are replaced with a selection of substituents from the indicated group, provided that the normal valency is not exceeded, and that the substitution results in a chemically stable compound, i.e. a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into a therapeutic agent.

The term "subject" as used herein, refers to an animal, preferably a mammal, most preferably a human, who is or has been the object of treatment, observation or experiment. As used herein, the term “subject” therefore encompasses patients, as well as asymptomatic or presymptomatic individuals at risk of developing a disease or condition as defined herein.

The term "therapeutically effective amount" as used herein, means that amount of active compound or pharmaceutical agent that elicits the biological or medicinal response in a tissue system, animal or human that is being sought by a researcher, veterinarian, medical doctor or other clinician, which includes alleviation of the symptoms of the disease or disorder being treated. The term "prophylactically effective amount" as used herein, means that amount of active compound or pharmaceutical agent that substantially reduces the potential for onset of the disease or disorder being prevented.

As used herein, the term "composition" is intended to encompass a product comprising the specified ingredients in the specified amounts, as well as any product which results, directly or indirectly, from combinations of the specified ingredients in the specified amounts.

Hereinbefore and hereinafter, the term “compound of Formula (I)” is meant to include the addition salts, the solvates and the stereoisomers thereof.

The terms “stereoisomers” or “stereochemically isomeric forms” hereinbefore or hereinafter are used interchangeably.

The invention includes all stereoisomers of the compound of Formula (I) either as a pure stereoisomer or as a mixture of two or more stereoisomers.

Enantiomers are stereoisomers that are non-superimposable mirror images of each other. A 1 : 1 mixture of a pair of enantiomers is a racemate or racemic mixture. Diastereomers (or diastereoi somers) are stereoisomers that are not enantiomers, i.e. they are not related as mirror images. If a compound contains a double bond, the substituents may be in the E or the Z configuration. If a compound contains a disubstituted cycloalkyl group, the substituents may be in the cis or trans configuration. Therefore, the invention includes enantiomers, diastereomers, racemates, E isomers, Z isomers, cis isomers, trans isomers and mixtures thereof.

The absolute configuration is specified according to the Cahn-Ingold-Prelog system. The configuration at an asymmetric atom is specified by either R or S. Resolved compounds whose absolute configuration is not known can be designated by (+) or (-) depending on the direction in which they rotate plane polarized light.

When a specific stereoisomer is identified, this means that said stereoisomer is substantially free, i.e. associated with less than 50%, preferably less than 20%, more preferably less than 10%, even more preferably less than 5%, in particular less than 2% and most preferably less than 1%, of the other isomers. Thus, when a compound of formula (I) is for instance specified as (R), this means that the compound is substantially free of the (S) isomer; when a compound of formula (I) is for instance specified as E, this means that the compound is substantially free of the Z isomer; when a compound of formula (I) is for instance specified as cis, this means that the compound is substantially free of the trans isomer. For use in medicine, the addition salts of the compounds of this invention refer to non toxic "pharmaceutically acceptable addition salts". Other salts may, however, be useful in the preparation of compounds according to this invention or of their pharmaceutically acceptable addition salts. Suitable pharmaceutically acceptable addition salts of the compounds include acid addition salts which may, for example, be formed by mixing a solution of the compound with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulfuric acid, fumaric acid, maleic acid, succinic acid, acetic acid, benzoic acid, citric acid, tartaric acid, carbonic acid or phosphoric acid. Furthermore, where the compounds of the invention carry an acidic moiety, suitable pharmaceutically acceptable addition salts thereof may include alkali metal salts, e.g., sodium or potassium salts; alkaline earth metal salts, e.g., calcium or magnesium salts; and salts formed with suitable organic ligands, e.g., quaternary ammonium salts.

Representative acids which may be used in the preparation of pharmaceutically acceptable addition salts include, but are not limited to, the following: acetic acid, 2,2-dichloroactic acid, acylated amino acids, adipic acid, alginic acid, ascorbic acid, L-aspartic acid, benzenesulfonic acid, benzoic acid, 4- acetamidobenzoic acid, (+)-camphoric acid, camphorsulfonic acid, capric acid, caproic acid, caprylic acid, cinnamic acid, citric acid, cyclamic acid, ethane- 1,2-disulfonic acid, ethanesulfonic acid, 2-hydroxy-ethanesulfonic acid, formic acid, fumaric acid, galactaric acid, gentisic acid, glucoheptonic acid, D-gluconic acid, D-glucoronic acid, L-glutamic acid, beta- oxo-glutaric acid, glycolic acid, hippuric acid, hydrobromic acid, hydrochloric acid, (+)-L-lactic acid, (±)-DL-lactic acid, lactobionic acid, maleic acid, (-)-L-malic acid, malonic acid, (±)-DL-mandelic acid, methanesulfonic acid, naphthalene-2-sulfonic acid, naphthalene- 1,5- disulfonic acid, l-hydroxy-2-naphthoic acid, nicotinic acid, nitric acid, oleic acid, orotic acid, oxalic acid, palmitic acid, pamoic acid, phosphoric acid, L- pyroglutamic acid, salicylic acid, 4-amino-salicylic acid, sebacic acid, stearic acid, succinic acid, sulfuric acid, tannic acid, (+)-L-tartaric acid, thiocyanic acid, p-toluenesulfonic acid, trifluoromethylsulfonic acid, and undecylenic acid. Representative bases which may be used in the preparation of pharmaceutically acceptable addition salts include, but are not limited to, the following: ammonia, L-arginine, benethamine, benzathine, calcium hydroxide, choline, dimethylethanol- amine, diethanolamine, diethylamine, 2-(diethylamino)-ethanol, ethanolamine, ethylene-diamine, l-methyl-glucamine, hydrabamine, 1 //-imidazole, L-lysine, magnesium hydroxide, 4-(2-hydroxyethyl)-morpholine, piperazine, potassium hydroxide, l-(2-hydroxyethyl)-pyrrolidine, secondary amine, sodium hydroxide, triethanolamine, tromethamine and zinc hydroxide.

The names of compounds were generated according to the nomenclature rules agreed upon by the Chemical Abstracts Service (CAS) or according to the nomenclature rules agreed upon by the International Union of Pure and Applied Chemistry (IUPAC).

PREPARATION OF THE FINAL COMPOUNDS

The compounds according to the invention can generally be prepared by a succession of steps, each of which is known to the skilled person. In particular, the compounds can be prepared according to the following synthesis methods.

The compounds of Formula (I) may be synthesized in the form of racemic mixtures of enantiomers which can be separated from one another following art-known resolution procedures. The racemic compounds of Formula (I) may be converted into the corresponding diastereomeric salt forms by reaction with a suitable chiral acid.

Said diastereomeric salt forms are subsequently separated, for example, by selective or fractional crystallization and the enantiomers are liberated therefrom by alkali. An alternative manner of separating the enantiomeric forms of the compounds of Formula (I) involves liquid chromatography using a chiral stationary phase. Said pure stereochemically isomeric forms may also be derived from the corresponding pure stereochemically isomeric forms of the appropriate starting materials, provided that the reaction occurs stereospecifically.

EXPERIMENTAL PROCEDURE 1

The final compounds of Formula (I) can be prepared by reacting an intermediate compound of Formula (II) with a compound of Formula (III) according to reaction scheme (1). The reaction is performed in a suitable reaction-inert solvent, such as, for example, dichloromethane, a metal hydride, such as, for example sodium triacetoxyborohydride, sodium cyanoborohydride or sodium borohydride, and sometimes may require the presence of a suitable acid, such as acetic acid, or the presence of a suitable base, such as, for example, triethylamine, and/or a Lewis acid, such as, for example titanium tetraisopropoxide or titanium tetrachloride. The reaction is usually carried out at room temperature, stirring for example for 1 hour or up to 24 hours. In reaction scheme (1) all variables are defined as in Formula (I).

Reaction scheme 1

EXPERIMENTAL PROCEDURE 2

Additionally, final compounds of Formula (I) can be prepared by reacting an intermediate compound of Formula (II) with a compound of Formula (IV) according to reaction scheme (2). The reaction is performed in a suitable reaction-inert solvent, such as, for example, acetonitrile or DMF, a suitable base, such as, for example, potassium carbonate, cesium carbonate, triethylamine or diisopropylethylamine, under thermal conditions, such as, 75 °C or 80 °C, for example for 1 hour or up to 24 hours. In reaction scheme (2) all variables are defined as in Formula (I), and wherein halo is chloro, bromo or iodo.

Reaction scheme 2

EXPERIMENTAL PROCEDURE 3

Additionally, final compounds of Formula (I), wherein R = CFF, herein referred to as (I-b), can be prepared by reacting an intermediate compound of Formula (II) with a compound of Formula (V) followed by reaction of the formed imine derivative with a reagent of Formula (VI) according to reaction scheme (3). The reaction is performed in a suitable reaction-inert solvent, such as, for example, anhydrous dichloromethane, a Lewis acid, such as, for example titanium tetraisopropoxide or titanium tetrachloride, usually at room temperature, for example for 16 hours to 24 hours. In reaction scheme (3) all variables are defined as in Formula (I), and wherein halo is chloro, bromo or iodo.

EXPERIMENTAL PROCEDURE 4 Intermediate compounds of Formula (II) can be prepared cleaving a protecting group (PG) in an intermediate compound of Formula (VII) according to reaction scheme (4). In reaction scheme (4) all variables are defined as in Formula (I), and PG is a suitable protecting group of the nitrogen function such as, for example, tert- butoxycarbonyl (Boc), ethoxycarbonyl, benzyl, benzyloxycarbonyl (Cbz). Suitable methods for removing such protecting groups are widely known to the person skilled in the art and comprise but are not limited to: Boc deprotection: treatment with a protic acid, such as, for example, trifluoroacetic acid or hydrochloric acid, in a reaction inert solvent, such as, for example, dichloromethane or 1,4-dioxane; ethoxycarbonyl deprotection: treatment with a strong base, such as, for example, sodium hydroxide, in a reaction inert solvent such as for example wet tetrahydrofuran; benzyl deprotection: catalytic hydrogenation in the presence of a suitable catalyst, such as, for example, palladium on carbon, in a reaction inert solvent, such as, for example, methanol or ethanol; benzyloxycarbonyl deprotection: catalytic hydrogenation in the presence of a suitable catalyst, such as, for example, palladium on carbon, in a reaction inert solvent, such as, for example, methanol or ethanol.

Reaction scheme 4 EXPERIMENTAL PROCEDURE 5

Intermediate compounds of Formula (Vll-a), wherein L ^A = -0-, can be prepared by reaction of a hydroxy compound of Formula (VIII) and a halo derivative of Formula (IX) according to reaction scheme (5). The reaction is performed in a suitable reaction- inert solvent, such as, for example, dimethylformamide or dimethylsulfoxide, and a suitable base, such as, sodium hydride or potassium tert-butoxide, under thermal conditions, such as, for example, 60 °C, for example for 4 or 18 hours. In reaction scheme (5) all variables are defined as in Formula (I), and halo is preferably chloro, bromo or iodo. PG is defined as in Formula (VII).

(VIII) ( ^Vl| - ^a )

Reaction scheme 5

EXPERIMENTAL PROCEDURE 6

Alternatively, intermediate compounds of Formula (Vll-a), wherein L ^A = -0-, can also be prepared by reaction of a hydroxy compound of Formula (VIII) and a nitro derivative of Formula (X) according to reaction scheme (6). The reaction is performed in a suitable reaction-inert solvent, such as, for example, tetrahydrofuran, and a suitable base, such as sodium hydride, under thermal conditions, such as, for example, stirring at 50 °C or 60 °C overnight. In reaction scheme (6) all variables are defined as in Formula (I). PG is defined as in Formula (VII).

(VIII) (Vll-a)

Reaction scheme 6

EXPERIMENTAL PROCEDURE 7

Intermediate compounds of Formula (Vll-b), wherein L ^A = -CH2-O-, can be prepared by reaction of a hydroxy compound of Formula (VIII) and a halo derivative of Formula (XI) according to reaction scheme (7). The reaction is performed in a suitable reaction-inert solvent, such as, for example, dimethylformamide or acetonitrile, and a suitable base, such as, sodium hydride or sodium tert-butoxide, under thermal conditions, such as, for example, room temperature or 40 °C overnight, or 60 °C for 90 min. In reaction scheme (7) all variables are defined as in Formula (I), and halo is preferably chloro, bromo or iodo. PG is defined as in Formula (VII).

Reaction scheme 7 EXPERIMENTAL PROCEDURE 8

Intermediate compounds of Formula (VII-c), wherein L ^A = -O-CH2-, can be prepared by “Mitsunobu reaction” of a hydroxy compound of Formula (XII) and a hydroxy derivative of Formula (XIII) according to reaction scheme (8). The reaction is performed in a suitable reaction-inert solvent, such as, for example, toluene or tetrahydrofuran, a phosphine, such as, triphenylphosphine, a suitable coupling agent, such as, for example DIAD (CAS: 2446-83-5), under thermal conditions, such as, for example, 70 °C, for example for 16 hours. In reaction scheme (8) all variables are defined as in Formula (I). PG is defined as in Formula (VII). Reaction scheme 8

Intermediates of Formulae (III), (IV), (V), (VI), (VIII), (IX), (X), (XI), (XII) and (XIII) are commercially available or can be prepared by known procedures to those skilled in the art. PHARMACOLOGY

The compounds of the present invention and the pharmaceutically acceptable compositions thereof inhibit O-GlcNAc hydrolase (OGA) and therefore may be useful in the treatment or prevention of diseases involving tau pathology, also known as tauopathies, and diseases with tau inclusions. Such diseases include, but are not limited to Alzheimer’s disease, amyotrophic lateral sclerosis and parkinsonism-dementia complex, argyrophilic grain disease, chronic traumatic encephalopathy, corticobasal degeneration, diffuse neurofibrillary tangles with calcification, Down’s syndrome, Familial British dementia, Familial Danish dementia, Frontotemporal dementia and parkinsonism linked to chromosome 17 (caused by MAPT mutations), Frontotemporal lobar degeneration (some cases caused by C90RF72 mutations), Gerstmann-Straussler- Scheinker disease, Parkinson’s disease, Guadeloupean parkinsonism, myotonic dystrophy, neurodegeneration with brain iron accumulation, Niemann-Pick disease, type C, non-Guamanian motor neuron disease with neurofibrillary tangles, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, progressive supranuclear palsy, SLC9A6-related mental retardation, subacute sclerosing panencephalitis, tangle-only dementia, and white matter tauopathy with globular glial inclusions.

The compounds of the present invention and the pharmaceutically acceptable compositions thereof inhibit O-GlcNAc hydrolase (OGA) and therefore may be also useful in the treatment or prevention of diseases involving an alpha synucleinopathy, in particular Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease.

As used herein, the term “treatment” is intended to refer to all processes, wherein there may be a slowing, interrupting, arresting or stopping of the progression of a disease or an alleviation of symptoms, but does not necessarily indicate a total elimination of all symptoms. As used herein, the term “prevention” is intended to refer to all processes, wherein there may be a slowing, interrupting, arresting or stopping of the onset of a disease.

The invention also relates to a compound according to the general Formula (I), a stereoisomeric form thereof or a pharmaceutically acceptable acid or base addition salt thereof, for use in the treatment or prevention of diseases or conditions selected from the group consisting of Alzheimer’s disease, amyotrophic lateral sclerosis and parkinsonism-dementia complex, argyrophilic grain disease, chronic traumatic encephalopathy, corticobasal degeneration, diffuse neurofibrillary tangles with calcification, Down’s syndrome, Familial British dementia, Familial Danish dementia, Frontotemporal dementia and parkinsonism linked to chromosome 17 (caused by MAPT mutations), Frontotemporal lobar degeneration (some cases caused by C90RF72 mutations), Gerstmann-Straussler-Scheinker disease, Guadeloupean parkinsonism, myotonic dystrophy, neurodegeneration with brain iron accumulation, Niemann-Pick disease, type C, non-Guamanian motor neuron disease with neurofibrillary tangles, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, progressive supranuclear palsy, SLC9A6-related mental retardation, subacute sclerosing panencephalitis, tangle- only dementia, white matter tauopathy with globular glial inclusions, Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, and alpha synucleinopathy caused by Gaucher’s disease.

The invention also relates to a compound according to the general Formula (I), a stereoisomeric form thereof or a pharmaceutically acceptable acid or base addition salt thereof, for use in the treatment, prevention, amelioration, control or reduction of the risk of diseases or conditions selected from the group consisting of Alzheimer’s disease, amyotrophic lateral sclerosis and parkinsonism-dementia complex, argyrophilic grain disease, chronic traumatic encephalopathy, corticobasal degeneration, diffuse neurofibrillary tangles with calcification, Down’s syndrome, Familial British dementia, Familial Danish dementia, Frontotemporal dementia and parkinsonism linked to chromosome 17 (caused by MAPT mutations), Frontotemporal lobar degeneration (some cases caused by C90RF72 mutations), Gerstmann-Straussler- Scheinker disease, Guadeloupean parkinsonism, myotonic dystrophy, neurodegeneration with brain iron accumulation, Niemann-Pick disease, type C, non- Guamanian motor neuron disease with neurofibrillary tangles, Pick’s disease, postencephalitic parkinsonism, prion protein cerebral amyloid angiopathy, progressive subcortical gliosis, progressive supranuclear palsy, SLC9A6-related mental retardation, subacute sclerosing panencephalitis, tangle-only dementia, white matter tauopathy with globular glial inclusions, Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, and alpha synucleinopathy caused by Gaucher’s disease. In particular, the diseases or conditions may in particular be selected from a tauopathy, more in particular a tauopathy selected from the group consisting of Alzheimer’s disease, progressive supranuclear palsy, Down’s syndrome, frontotemporal lobe dementia, frontotemporal dementia with Parkinsonism- 17, Pick’s disease, corticobasal degeneration, and agryophilic grain disease; or the diseases or conditions may in particular be neurodegenerative diseases accompanied by a tau pathology, more in particular a neurodegenerative disease selected from amyotrophic lateral sclerosis or frontotemporal lobe dementia caused by C90RF72 mutations.

In particular, the diseases or conditions may in particular be selected from an alpha synuclinopathy, more in particular a tauopathy selected from the group consisting of Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, and alpha synucleinopathy caused by Gaucher’s disease.

Preclinical states in Alzheimer’s and tauopathy diseases:

In recent years the United States (US) National Institute for Aging and the International Working Group have proposed guidelines to better define the preclinical (asymptomatic) stages of AD (Dubois B, et al. Lancet Neurol. 2014;13:614-629; Sperling, RA, et al. Alzheimers Dement. 2011;7:280-292). Hypothetical models postulate that Ab accumulation and tau-aggregation begins many years before the onset of overt clinical impairment. The key risk factors for elevated amyloid accumulation, tau-aggregation and development of AD are age (i.e, 65 years or older), APOE genotype, and family history. Approximately one third of clinically normal older individuals over 75 years of age demonstrate evidence of Ab or tau accumulation on PET amyloid and tau imaging studies, the latter being less advanced currently. In addition, reduced Abeta-levels in CSF measurements are observed, whereas levels of non-modified as well as phosphorylated tau are elevated in CSF. Similar findings are seen in large autopsy studies and it has been shown that tau aggregates are detected in the brain as early as 20 years of age and younger. Amyloid-positive (Ab+) clinically normal individuals consistently demonstrate evidence of an “AD-like endophenotype” on other biomarkers, including disrupted functional network activity in both functional magnetic resonance imaging (MRI) and resting state connectivity, fluorodeoxyglucose ¹⁸ F (FDG) hypometabolism, cortical thinning, and accelerated rates of atrophy. Accumulating longitudinal data also strongly suggests that Ab+ clinically normal individuals are at increased risk for cognitive decline and progression to mild cognitive impairment (MCI) and AD dementia. The Alzheimer’s scientific community is of the consensus that these Ab+ clinically normal individuals represent an early stage in the continuum of AD pathology. Thus, it has been argued that intervention with a therapeutic agent that decreases Ab production or the aggregation of tau is likely to be more effective if started at a disease stage before widespread neurodegeneration has occurred. A number of pharmaceutical companies are currently testing BACE inhibition in prodromal AD.

Thanks to evolving biomarker research, it is now possible to identify Alzheimer’s disease at a preclinical stage before the occurrence of the first symptoms. All the different issues relating to preclinical Alzheimer’s disease such as, definitions and lexicon, the limits, the natural history, the markers of progression and the ethical consequences of detecting the disease at the asymptomatic stage, are reviewed in Alzheimer’s & Dementia 12 (2016) 292-323.

Two categories of individuals may be recognized in preclinical Alzheimer’s disease or tauopathies. Cognitively normal individuals with amyloid beta or tau aggregation evident on PET scans, or changes in CSF Abeta, tau and phospho-tau are defined as being in an “asymptomatic at-risk state for Alzheimer’s disease (AR-AD)” or in a “asymptomatic state of tauopathy”. Individuals with a fully penetrant dominant autosomal mutation for familial Alzheimer’s disease are said to have “presymptomatic Alzheimer’s disease”. Dominant autosomal mutations within the tau-protein have been described for multiple forms of tauopathies as well.

Thus, in an embodiment, the invention also relates to a compound according to the general Formula (I), a stereoisomeric form thereof or a pharmaceutically acceptable acid or base addition salt thereof, for use in control or reduction of the risk of preclinical Alzheimer’s disease, prodromal Alzheimer’s disease, or tau-related neurodegeneration as observed in different forms of tauopathies.

Prodromal states of Parkinson’s disease have also been studied. Thus, in an embodiment, the invention also relates to a compound according to the general Formula (I), a stereoisomeric form thereof or a pharmaceutically acceptable acid or base addition salt thereof, for use in control or reduction of the risk of prodromal Parkinson’s disease.

As already mentioned hereinabove, the term “treatment” does not necessarily indicate a total elimination of all symptoms, but may also refer to symptomatic treatment in any of the disorders mentioned above. In view of the utility of the compound of Formula (I), there is provided a method of treating subjects such as warm-blooded animals, including humans, suffering from or a method of preventing subjects such as warm blooded animals, including humans, suffering from any one of the diseases mentioned hereinbefore.

Said methods comprise the administration, i.e. the systemic or topical administration, preferably oral administration, of a prophylactically or a therapeutically effective amount of a compound of Formula (I), a stereoisomeric form thereof, a pharmaceutically acceptable addition salt or solvate thereof, to a subject such as a warm-blooded animal, including a human.

Therefore, the invention also relates to a method for the prevention and/or treatment of any of the diseases mentioned hereinbefore comprising administering a prophylactically or a therapeutically effective amount of a compound according to the invention to a subject in need thereof.

The invention also relates to a method for modulating O-GlcNAc hydrolase (OGA) activity, comprising administering to a subject in need thereof, a prophylactically or a therapeutically effective amount of a compound according to the invention and as defined in the claims or a pharmaceutical composition according to the invention and as defined in the claims.

A method of treatment may also include administering the active ingredient on a regimen of between one and four intakes per day. In these methods of treatment the compounds according to the invention are preferably formulated prior to administration. As described herein below, suitable pharmaceutical formulations are prepared by known procedures using well known and readily available ingredients.

The compounds of the present invention, that can be suitable to treat or prevent any of the disorders mentioned above or the symptoms thereof, may be administered alone or in combination with one or more additional therapeutic agents. Combination therapy includes administration of a single pharmaceutical dosage formulation which contains a compound of Formula (I) and one or more additional therapeutic agents, as well as administration of the compound of Formula (I) and each additional therapeutic agent in its own separate pharmaceutical dosage formulation. For example, a compound of Formula (I) and a therapeutic agent may be administered to the patient together in a single oral dosage composition such as a tablet or capsule, or each agent may be administered in separate oral dosage formulations.

A skilled person will be familiar with alternative nomenclatures, nosologies, and classification systems for the diseases or conditions referred to herein. For example, the fifth edition of the Diagnostic & Statistical Manual of Mental Disorders (DSM-5™) of the American Psychiatric Association utilizes terms such as neurocognitive disorders (NCDs) (both major and mild), in particular, neurocognitive disorders due to Alzheimer’s disease. Such terms may be used as an alternative nomenclature for some of the diseases or conditions referred to herein by the skilled person. PHARMACEUTICAL COMPOSITIONS

The present invention also provides compositions for preventing or treating diseases in which inhibition of O-GlcNAc hydrolase (OGA) is beneficial, such as Alzheimer’s disease, progressive supranuclear palsy, Down’s syndrome, frontotemporal lobe dementia, frontotemporal dementia with Parkinsonism- 17, Pick’s disease, corticobasal degeneration, agryophilic grain disease, amyotrophic lateral sclerosis, frontotemporal lobe dementia caused by C90RF72 mutations, Parkinson’s disease, dementia due to Parkinson’s (or neurocognitive disorder due to Parkinson’s disease), dementia with Lewy bodies, multiple system atrophy, or alpha synucleinopathy caused by Gaucher’s disease, said compositions comprising a therapeutically effective amount of a compound according to formula (I) and a pharmaceutically acceptable carrier or diluent.

While it is possible for the active ingredient to be administered alone, it is preferable to present it as a pharmaceutical composition. Accordingly, the present invention further provides a pharmaceutical composition comprising a compound according to the present invention, together with a pharmaceutically acceptable carrier or diluent. The carrier or diluent must be “acceptable” in the sense of being compatible with the other ingredients of the composition and not deleterious to the recipients thereof.

The pharmaceutical compositions of this invention may be prepared by any methods well known in the art of pharmacy. A therapeutically effective amount of the particular compound, in base form or addition salt form, as the active ingredient is combined in intimate admixture with a pharmaceutically acceptable carrier, which may take a wide variety of forms depending on the form of preparation desired for administration. These pharmaceutical compositions are desirably in unitary dosage form suitable, preferably, for systemic administration such as oral, percutaneous or parenteral administration; or topical administration such as via inhalation, a nose spray, eye drops or via a cream, gel, shampoo or the like. For example, in preparing the compositions in oral dosage form, any of the usual pharmaceutical media may be employed, such as, for example, water, glycols, oils, alcohols and the like in the case of oral liquid preparations such as suspensions, syrups, elixirs and solutions; or solid carriers such as starches, sugars, kaolin, lubricants, binders, disintegrating agents and the like in the case of powders, pills, capsules and tablets. Because of their ease in administration, tablets and capsules represent the most advantageous oral dosage unit form, in which case solid pharmaceutical carriers are obviously employed. For parenteral compositions, the carrier will usually comprise sterile water, at least in large part, though other ingredients, for example, to aid solubility, may be included. Injectable solutions, for example, may be prepared in which the carrier comprises saline solution, glucose solution or a mixture of saline and glucose solution. Injectable suspensions may also be prepared in which case appropriate liquid carriers, suspending agents and the like may be employed. In the compositions suitable for percutaneous administration, the carrier optionally comprises a penetration enhancing agent and/or a suitable wettable agent, optionally combined with suitable additives of any nature in minor proportions, which additives do not cause any significant deleterious effects on the skin. Said additives may facilitate the administration to the skin and/or may be helpful for preparing the desired compositions. These compositions may be administered in various ways, e.g., as a transdermal patch, as a spot-on or as an ointment.

It is especially advantageous to formulate the aforementioned pharmaceutical compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used in the specification and claims herein refers to physically discrete units suitable as unitary dosages, each unit containing a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Examples of such dosage unit forms are tablets (including scored or coated tablets), capsules, pills, powder packets, wafers, injectable solutions or suspensions, teaspoonfuls, tablespoonfuls and the like, and segregated multiples thereof.

The exact dosage and frequency of administration depends on the particular compound of Formula (I) used, the particular condition being treated, the severity of the condition being treated, the age, weight, sex, extent of disorder and general physical condition of the particular patient as well as other medication the individual may be taking, as is well known to those skilled in the art. Furthermore, it is evident that said effective daily amount may be lowered or increased depending on the response of the treated subject and/or depending on the evaluation of the physician prescribing the compounds of the instant invention.

Depending on the mode of administration, the pharmaceutical composition will comprise from 0.05 to 99% by weight, preferably from 0.1 to 70% by weight, more preferably from 0.1 to 50% by weight of the active ingredient, and, from 1 to 99.95% by weight, preferably from 30 to 99.9% by weight, more preferably from 50 to 99.9% by weight of a pharmaceutically acceptable carrier, all percentages being based on the total weight of the composition.

The present compounds can be used for systemic administration such as oral, percutaneous or parenteral administration; or topical administration such as via inhalation, a nose spray, eye drops or via a cream, gel, shampoo or the like. The compounds are preferably orally administered. The exact dosage and frequency of administration depends on the particular compound according to Formula (I) used, the particular condition being treated, the severity of the condition being treated, the age, weight, sex, extent of disorder and general physical condition of the particular patient as well as other medication the individual may be taking, as is well known to those skilled in the art. Furthermore, it is evident that said effective daily amount may be lowered or increased depending on the response of the treated subject and/or depending on the evaluation of the physician prescribing the compounds of the instant invention.

The amount of a compound of Formula (I) that can be combined with a carrier material to produce a single dosage form will vary depending upon the disease treated, the mammalian species, and the particular mode of administration. However, as a general guide, suitable unit doses for the compounds of the present invention can, for example, preferably contain between 0.1 mg to about 1000 mg of the active compound. A preferred unit dose is between 1 mg to about 500 mg. A more preferred unit dose is between 1 mg to about 300 mg. Even more preferred unit dose is between 1 mg to about 100 mg. Such unit doses can be administered more than once a day, for example, 2, 3, 4, 5 or 6 times a day, but preferably 1 or 2 times per day, so that the total dosage for a 70 kg adult is in the range of 0.001 to about 15 mg per kg weight of subject per administration. A preferred dosage is 0.01 to about 1.5 mg per kg weight of subject per administration, and such therapy can extend for a number of weeks or months, and in some cases, years. It will be understood, however, that the specific dose level for any particular patient will depend on a variety of factors including the activity of the specific compound employed; the age, body weight, general health, sex and diet of the individual being treated; the time and route of administration; the rate of excretion; other drugs that have previously been administered; and the severity of the particular disease undergoing therapy, as is well understood by those of skill in the area.

A typical dosage can be one 1 mg to about 100 mg tablet or 1 mg to about 300 mg taken once a day, or, multiple times per day, or one time-release capsule or tablet taken once a day and containing a proportionally higher content of active ingredient. The time-release effect can be obtained by capsule materials that dissolve at different pH values, by capsules that release slowly by osmotic pressure, or by any other known means of controlled release.

It can be necessary to use dosages outside these ranges in some cases as will be apparent to those skilled in the art. Further, it is noted that the clinician or treating physician will know how and when to start, interrupt, adjust, or terminate therapy in conjunction with individual patient response.

The invention also provides a kit comprising a compound according to the invention, prescribing information also known as “leaflet”, a blister package or bottle, and a container. Furthermore, the invention provides a kit comprising a pharmaceutical composition according to the invention, prescribing information also known as “leaflet”, a blister package or bottle, and a container. The prescribing information preferably includes advice or instructions to a patient regarding the administration of the compound or the pharmaceutical composition according to the invention. In particular, the prescribing information includes advice or instruction to a patient regarding the administration of said compound or pharmaceutical composition according to the invention, on how the compound or the pharmaceutical composition according to the invention is to be used, for the prevention and/or treatment of a tauopathy in a subject in need thereof. Thus, in an embodiment, the invention provides a kit of parts comprising a compound of Formula (I) or a stereoisomeric for thereof, or a pharmaceutically acceptable salt or a solvate thereof, or a pharmaceutical composition comprising said compound, and instructions for preventing or treating a tauopathy. The kit referred to herein can be, in particular, a pharmaceutical package suitable for commercial sale. For the compositions, methods and kits provided above, one of skill in the art will understand that preferred compounds for use in each are those compounds that are noted as preferred above. Still further preferred compounds for the compositions, methods and kits are those compounds provided in the non-limiting Examples below. EXPERIMENTAL PART

Hereinafter, the term “m.p.” means melting point, “min” means minutes, “ACN” means acetonitrile, “aq.” means aqueous, “Boc” means /cvV-butyloxy carbonyl, “DCM” means dichloromethane, “DIAD” means diisopropylazodicarboxylate, “DMF” means dimethylformamide, “DMSO” means dimethylsulfoxide, “Pd(PPh3)4” means tetrakis(triphenylphosphine)palladium(0), “Pd ₂ (dba) ₃ ” means tris(dibenzylideneacetone)dipalladium(0), “X-Phos” means 2-dicyclohexylphosphino- 2',4',6'-tri-isopropyl-l,r-biphenyl, “rt” or “RT” means room temperature, “rac” or “RS” means racemic, “LC-MS” means liquid chromatography/mass spectrometry, “HPLC” means high-performance liquid chromatography, “RP” means reversed phase, “R _t ” means retention time (in minutes), “[M+H] ⁺ ” means the protonated mass of the free base of the compound, “wt” means weight, “EtOAc” means ethyl acetate, “MeOH” means methanol, “sat” means saturated, “soltn” or “sol.” means solution, “TBAF” means tetrabutylammonium fluoride, “TFA” means trifluoroacetic acid, “TMDA” means N,N,N’N’-tetramethylethylenediamine, “SFC” means supercritical fluid chromatography, and “SFC-MS” means supercritical fluid chromatography/mass spectrometry.

Whenever the notation “RS” is indicated herein, it denotes that the compound is a racemic mixture at the indicated centre, unless otherwise indicated. The stereochemical configuration for centres in some compounds has been designated “i?” or “X” when the mixture(s) was separated; for some compounds, the stereochemical configuration at indicated centres has been designated as “i?*” or ‘A*” when the absolute stereochemistry is undetermined although the compound itself has been isolated as a single stereoisomer and is enantiomerically/diastereomerically pure. The enantiomeric excess of compounds reported herein was determined by analysis of the racemic mixture by supercritical fluid chromatography (SFC) followed by SFC comparison of the separated enantiomer(s).

Microwave assisted reactions were performed in a single-mode reactor: Initiator TM Sixty EXP microwave reactor (Biotage AB).

Thin layer chromatography (TLC) was carried out on silica gel 60 F254 plates (Merck) using reagent grade solvents. Open column chromatography was performed on silica gel, particle size 60 A, mesh = 230-400 (Merck) using standard techniques.

Automated flash column chromatography was performed using ready-to-connect cartridges, on irregular silica gel, particle size 15-40 pm (normal phase disposable flash columns) on different flash systems: either a SPOT or LAFLASH systems from Armen Instrument, or PuriFlash® 430evo systems from Interchim, or 971-FP systems from Agilent, or Isolera lSV systems from Biotage.

PREPARATION OF THE INTERMEDIATES

PREPARATION OF INTERMEDIATE 1 Potassium /er/-butoxide (353 mg, 3.14 mmol) was added to a stirred solution of (2S,4S)-tert-butyl 4-hydroxy-2-methylpiperidine-l-carboxylate (CAS: 790667-99-1; 338 mg, 1.57 mmol) in DMSO (4.5 mL) at rt, followed by the addition of 4-chloro-2,6- dimethylpyridine (CAS: 3512-75-2; 223 mg, 1.57 mmol) in a microwave vial under nitrogen at rt. Then the mixture was stirred at 60 °C for 18 h. The mixture was cooled down to rt, was treated with water and extracted with EtOAc. The organic layer was separated, dried (Na ₂ S0 ₄ ), filtered and the solvent was evaporated in vacuo. The crude product was purified by flash column chromatography (silica, EtOAc in DCM, 0/100 to 40/60). The desired fractions were collected and evaporated in vacuo to yield intermediate 1 (455 mg, 90%) as an oil.

PREPARATION OF INTERMEDIATE 2

Intermediate 2 was prepared following an analogous procedure to the one described for the synthesis of intermediate 1, using ( 2N, 4/^ ) - / /V-b ut y 1 4-hydroxy-2-methylpiperidine- 1-carboxylate (CAS: 790667-91-3) as starting material, and stirring the reaction mixture at 60 °C for 4 h. Intermediate 2 was obtained as an oil (72.5% yield).

PREPARATION OF INTERMEDIATE 3

Intermediate 3 was prepared following an analogous procedure to the one described for the synthesis of intermediate 1, using (2i?,4A)-/er/-butyl 4-hydroxy-2-methylpiperidine- 1-carboxylate (CAS: 790668-06-3) as starting material, and stirring the reaction mixture at 60 °C for 4 h. Intermediate 3 was obtained as an oil (51.6% yield).

PREPARATION OF INTERMEDIATE 4 Di-/er/-butyl azodicarboxylate (CAS: 870-50-8; 240.6 mg, 1.05 mmol) was added to a mixture of (2V,4//)-/ _<2/7 -butyl 4-hydroxy-2-methylpiperi dine- 1-carboxylate (CAS: 790667-91-3; 150 mg, 0.70 mmol), 5-hydroxy-2-methylpyridine (CAS: 1121-78-4; 76 mg, 0.70 mmol) and triphenylphosphine (274.1 mg, 1.05 mmol) in THF (1.5 mL) at 0 °C, and the resulting reaction mixture was stirred in a microwave oven at 120 °C for 20 min. Then, the solvent was evaporated in vacuo and the residue was purified by flash column chromatography (SiC , EtOAc in heptane 0/100 to 70/30). The desired fractions were collected and concentrated in vacuo to yield intermediate 4, contaminated with triphenylphosphine oxide, as a colorless oil, which was used in next step without further purification.

PREPARATION OF INTERMEDIATE 5 To a stirred solution of (2ri',4ri)-/er/-butyl 4-hydroxy-2-methylpiperidine-l-carboxylate (CAS: 790667-99-1; 200 mg, 0.93 mmol)) in DMF (4 mL) at 0 °C, sodium hydride (60% dispersion in mineral oil, 111.5 mg, 2.79 mmol) and 15-crown-5 (CAS: 33100- 27-5; 185 pL, 1.11 mmol) were added. Then, 2-chloro-4, 5-dimethyl pyridine ((CAS: 343268-69-9; 145 mg, 1.02 mmol) was added and the mixture was stirred at 80 °C for 16 h. Then, water was added at 0 °C and the mixture was extracted with DCM. The organic layer was separated, dried, filtered and solvents concentrated in vacuo. The residue was purified by flash column chromatography (SiCh, EtOAc in heptane 0/100 to 60/40). The desired fractions were collected and concentrated in vacuo to yield intermediate 5 as a colorless oil (153 mg, 51.4%). PREPARATION OF INTERMEDIATE 6

Trimethylboroxine (0.25 mL, 1.78 mmol) was added to a stirred suspension of intermediate 7 (260 mg, 0.71 mmol), K3PO4 (302 mg, 1.42 mmol), X-Phos (CAS: 564483-18-7; 33.9 mg, 0.07 mmol) and Pd2(dba)3 (32.6 mg, 0.036 mmol) in 1,4- dioxane under nitrogen. The mixture was stirred at 95 °C for 16 h. After cooling to rt water and EtOAc were added, the organic layer was separated, dried (MgS0 ₄ ) and filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in Heptane 0/100 to 80/20). The desired fractions were collected and concentrated in vacuo to yield intermediate 6 (151.7 mg, 65%) as a yellow oil. PREPARATION OF INTERMEDIATE 7

To a stirred solution of intermediate 8 (216 mg, 0.98 mmol) in dry THF (2 mL) at 0 °C sodium hydride (60% dispersion in mineral oil, 42.5 mg, 1.06 mmol) was added and the mixture was stirred for 30 minutes at 0 °C. Then, 2,6-dichloro-4-nitropyridine (CAS: 25194-01-8; 186.3 mg, 0.97 mmol) was added and the reaction mixture was stirred for 16 h at 50 °C. The reaction was quenched with a few drops of water at 0 °C. The mixture was diluted with sat. NaHCC and extracted with EtOAC. The organic layer was dried (MgSCE), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; DCM/MeOH (9: 1) in DCM 0/100 to 30/70). The desired fractions were collected and concentrated to yield intermediate 7 (260 mg, 73.7%) as a yellow solid.

PREPARATION OF INTERMEDIATE 8 TBAF (1.0 M solution in THF, 5.07 mL, 5.07 mmol) was added to a solution of intermediate 9 (564 mg, 1.69 mmol) in dry THF (10 mL) at 0 °C. The mixture was stirred at rt for 18 h. The reaction mixture was diluted with water and extracted with EtOAc (x2). The combined organic layer was washed with brine, dried (MgS0 ₄ ), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane 0/100 to 50/50). The desired fractions were collected and concentrated in vacuo to yield intermediate 8 (216 mg, 58.2%) as a yellowish oil.

PREPARATION OF INTERMEDIATE 9 Zirconium (IV) chloride (691 mg, 2.97 mmol) was added to a stirred solution of intermediate 10 (948 mg, 2.97 mmol) in dry THF (30 mL) at -20 °C. The mixture was stirred at -10 °C for 30 min. Then, methylmagnesium bromide (1.4 M solution in THF/toluene (1:3), 12.72 mL, 17.8 mmol) was added dropwise at -10°C for 10 min and the reaction mixture was stirred at -10 °C for 10 additional min. Then, the reaction mixture was stirred at rt for 18 h. The mixture was diluted with NFECl and extracted with EtOAc (3x). The combined organic layers were dried (MgS0 ₄ ), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane from 0/100 to 15/85). The desired fractions were collected and concentrated to yield intermediate 9 (564 mg, 57%) as a colourless oil.

PREPARATION OF INTERMEDIATE 10

Sodium hydride (60% dispersion in mineral oil, 568 mg, 14.19 mmol) was added in portions to a stirred solution of intermediate 11 (3.10 g, 13.5 mmol) in DMF (30 mL) at 0 °C. The mixture was stirred at rt for 30 min. Then, benzyl bromide (2.09 mL, 17.57 mmol) was added at 0 °C and the reaction mixture was stirred at rt for 18 h. The mixture was diluted with sat. NaHC0 ₃ and extracted with EtOAc (3x). The combined organic layers were washed with brine, dried (MgS0 ₄ ), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane from 0/100 to 70/30). The desired fractions were collected and concentrated to yield intermediate 10 (0.95 g, 22%) as a yellowish oil.

PREPARATION OF INTERMEDIATE 11

/tv/- Butyl di ethy 1 si 1 y 1 chloride (2.88 g, 19.11 mmol) was added portionwise to a stirred solution of 4-hydroxy-2-piperidinone (CAS: 476014-76-3; 2.0 g, 17.37 mmol) and imidazole (2.36 g, 34.74 mmol) in DCM (100 mL) at 0 °C. The reaction mixture was stirred at rt for 2 h. The mixture was filtered, the liquid phase was then washed with HC1 1M, NaHCCb and brine solution. The organic layer was separated, dried (MgSCE), filtered and the solvents evaporated in vacuo to yield intermediate 11 (3.1 g, 78%) as a colourless oil, which was used in the next step without further purification. PREPARATION OF INTERMEDIATE 12

Sodium hydride (60% dispersion in mineral oil, 217 mg, 1.39 mmol) was added to a stirred solution of (2S,4S)~ l-Boc-2-methyl-4-hydroxypiperi dine (CAS: 790667-99-1; 300 mg, 1.39 mmol) in DMF (80 mL) at rt. The mixture was stirred at rt for 15 min and then intermediate 13 (217 mg, 1.39 mmol) was added. The reaction mixture was stirred at rt for 16 h. Then, sat NH ₄ CI was added and the mixture was extracted with EtOAc. The organic layer was separated, dried over NaiSCE, filtered and concentrated in vacuo. The residue was purified by flash column chromatography (S1O2, EtOAc in heptane 0/100 to 100/0). The desired fractions were collected and concentrated in vacuo to yield intermediate 12 (353 mg, 75.7%) as a colorless oil.

PREPARATION OF INTERMEDIATE 13

To a stirred suspension of (2,6-dimethylpyridin-4-yl)methanol (CAS: 18088-01-2; 1.0 g, 7.26 mmol) in DCM (25 mL), was added thionyl chloride (2.14 mL, 29.45 mmol) at rt in sealed tube. The reaction mixture was stirred at 60 °C for 40 min. Then sat. NaHC0 ₃ was added. The organic layer was separated and washed with brine, dried (Na ₂ S0 ₄ ), filtered and concentrated in vacuo to yield intermediate 13 (714 mg, 63.2%) as a brown oil, which was used in the next step without further purification.

PREPARATION OF INTERMEDIATE 14

(2ri ^, ,4ri)-l-Boc-2-methyl-4-hydroxypiperidine (CAS: 790667-99-1; 79 mg, 0.73 mmol) was added to a mixture of sodium /<2/7-but oxide (105.8 mg, 1.10 mmol) in acetonitrile (2 mL) at 0 °C. After 30 min, 5-chloromethyl-2-methylpyridine (CAS: 52426-66-1; 103.9 mg, 0.73 mmol) was slowly added. After addition, the reaction mixture was heated at 40 °C for 16 h. The mixture was diluted with water and extracted with EtOAc. The organic layer was separated, dried (MgSCE), filtered and the solvents evaporated in vacuo. The crude was purified by flash column chromatography (silica; EtOAc in DCM 0/100 to 80/20). The desired fractions were collected, and solvents evaporated in vacuo to yield intermediate 14 (31.7 mg, 27%) as a colorless oil.

PREPARATION OF INTERMEDIATE 15

Intermediate 15 was prepared following an analogous procedure to the one described for the synthesis of intermediate 14, using 5-chloromethyl-2-methylpyridine (CAS: 52426-66-1) as starting material. Intermediate 15 was obtained as a colorless oil (27% yield).

PREPARATION OF INTERMEDIATE 16

Intermediate 16 was prepared following an analogous procedure to the one described for the synthesis of intermediate 14, using 5-chloromethyl-2-methylpyrimidine (CAS: 1427367-66-5) as starting material. Intermediate 16 was obtained as a colorless oil (41.6% yield).

PREPARATION OF INTERMEDIATE 17

Intermediate 17 was prepared following an analogous procedure to the one described for the synthesis of intermediate 14, using 3-(chloromethyl)-5-methyl-l,2,4-oxadiaxole (CAS: 1192-80-9) as starting material, and stirring the reaction mixture at rt for 16 h and then at 60 °C for 90 min. Intermediate 17 was obtained as a colorless oil (69% yield). PREPARATION OF INTERMEDIATE 18

Intermediate 18 was prepared following an analogous procedure to the one described for the synthesis of intermediate 12, using 4-(chloromethyl)-2-methoxy-6- methylpyridine (intermediate 19) as starting material, and stirring the reaction mixture at rt for 16 h and then at 60 °C for 90 min. Intermediate 18 was obtained as an oil (21.4% yield).

PREPARATION OF INTERMEDIATE 19 Thionyl chloride (0.75 mL, 10.07 mmol) was added dropwise to a solution of intermediate 20 (385 mg, 2.52 mmol) in DCM (10 mL) keeping the temperature at 0 - 3 °C. The reaction mixture was stirred at rt for 20 min. The mixture was cooled to 0 °C and NaHCCb was carefully added and the mixture was extracted with EtOAc. The combined organic layers were dried (MgSCri), filtered and evaporated in vacuo to yield intermediate 19 (427 mg, 99%) as a colorless oil.

PREPARATION OF INTERMEDIATE 20

Sodium borohydride (250 mg, 6.61 mmol) was added to a solution of 2-methoxy-6- methylisonicotinaldehyde (CAS: 951795-43-0; 0.50 g, 3.31 mmol) in EtOH (17 mL) at 0 °C. The mixture was stirred at 0 °C for 80 min. Water was added and the mixture was extracted with DCM. The organic layers were combined, dried (MgS0 ₄ ), filtered and concentrated in vacuo to give intermediate 20 (385.5 mg, 76%) as a colorless oil. PREPARATION OF INTERMEDIATES 21 AND 22

2,6-Dimethyl-4-hydroxypyridine (CAS: 13603-44-6; 316 mg, 2.49 mmol) and triphenylphosphine (824 mg, 3.11 mmol) were added to a stirred solution of intermediate 23 (546 mg, 2.07 mmol) in toluene (27 mL) under nitrogen atmosphere at rt. The mixture was stirred at rt for 15 min. Then, DIAD (0.62 mL, 3.11 mmol) diluted in toluene (3 mL) was added dropwise to the previous mixture at 70 °C. The mixture was stirred at 70 °C for 16 h. After this time the solvent was evaporated in vacuo. The residue was triturated with DIPE and filtered. Solvent from filtrate was evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane 0/100 to 68/32). The desired fractions were collected and concentrated in vacuo to yield a mixture of diastereomers as a colorless sticky solid (contaminated with triphenylphosphine oxide). The mixture of diastereomers was further purified by RP HPLC (stationary phase: C18 XBridge 30 x 100 mm 5 pm), (mobile phase: gradient from 90% [0.1% HCOOH] - 10% [MeCNMeOH (1:1)] to 54% [0.1% HCOOH] - 46% [MeCNMeOH (1:1)]. The desired fractions were collected, neutralized with sat. NaHCCb, partially evaporated in vacuo and extracted with DCM. The organic layer was separated, dried (MgSCE), filtered and the solvent evaporated in vacuo to yield intermediate 21 (321 mg, 32%) and intermediate 22 (121 mg, 12%) as colorless sticky solids.

PREPARATION OF INTERMEDIATE 23

Benzyl chloroformate (8.94 mL, 62.15 mmol) was added to a stirred solution of intermediate 24 (8.03 g, 62.15 mmol) and triethylamine (17.5 mL, 124.3 mmol) in DCM (34 mL) at 0°C. The reaction mixture was stirred at rt for 4 h. The solvent was evaporated in vacuo. The residue was diluted with sat. NaHC0 ₃ and extracted with EtOAc. The organic layer was separated, dried (MgS0 ₄ ), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane 0/100 to 37/63). The desired fractions were collected and concentrated in vacuo to yield intermediate 23 (cis/trans mixture 24/76, 6.57 g, 40.1%) as a colorless sticky solid.

PREPARATION OF INTERMEDIATE 24

Lithium aluminium hydride (7.67 g, 192.1 mmol) was added portionwise to a stirred suspension of intermediate 25 (12.4 g, 64 mmol) in dry THF (350 mL) at 0°C. The reaction mixture was stirred at 0 °C for 20 min and then at rt for additional 20 min. The mixture was quenched with water (7.3 mL), NaOH 15% w/v (7.3 mL) and water (21.9 mL) sequentially at 0 °C. The mixture was stirred at rt for 30 min, and then was extracted with EtOAc. The organic layer was separated, dried (MgSCL), filtered and the solvents evaporated in vacuo to yield intermediate 24 (cis/trans mixtures, 8.03 g, 97%) as a yellow waxy solid.

PREPARATION OF INTERMEDIATE 25

Pt0 ₂ (0.73 g, 3.22 mmol) was added to a stirred solution of methyl 6-methylnicotinate (CAS: 5470-70-2; 9.75 g, 64.5 mmol) in acetic acid (65 mL) and EtOH (85 mL). The mixture was stirred under EL atmosphere (10 bar) at rt for 16. The reaction mixture was recharged with EL 4 times (10 bar) until constant final pressure (8 bar aprox.). The mixture was filtered over a pad of celite® and the cake was washed with methanol several times. The solvents were evaporated in vacuo to yield intermediate 25 (14 g, 99.9%) as a yellow sticky solid. The product obtained was used in the next step without further purification.

PREPARATION OF INTERMEDIATE 26 . 2 HC1 1-26

Hydrogen chloride (4 M in 1,4-dioxane, 9 mL, 36 mmol) was added to intermediate 1 (0.45 g, 0.98 mmol) and the reaction mixture was stirred at rt for 5 h. The reaction mixture was concentrated to dryness to give intermediate 26 as hydrochloride salt (285 mg, 98.9%) as a white solid which was used in the next step without further purification.

PREPARATION OF INTERMEDIATE 27

Resin Amberlyst™ 15 PS-SO3 (4.11 mmol/g; 1.08 g, 5.06 mmol) was added to intermediate 2 (0.47 g, 1.01 mmol) in MeOH (50 mL). The reaction mixture was shaken at rt for 5h. The solvent was removed and discarded, and the resin was washed several times with MeOH. Then, a 7 N soln. of N¾ in MeOH was added to the resin and stirred for lh. The solvent was evaporated in vacuo, and the resin was washed again several times with 7N N¾ in MeOH. The organic solvent extracts were evaporated in vacuo to yield intermediate 27 (159 mg, 71.4%) as a brown oil.

PREPARATION OF INTERMEDIATE 28

Intermediate 28 was prepared following an analogous procedure to the one described for the synthesis of intermediate 27, using intermediate 3 as starting material. Intermediate 28 (100 mg, quant.) was obtained as an oil.

PREPARATION OF INTERMEDIATE 29

Intermediate 29 was prepared following an analogous procedure to the one described for the synthesis of intermediate 27, using intermediate 4 as starting material. Intermediate 29 (102.5 mg, 51.8%) was obtained as a colorless oil.

PREPARATION OF INTERMEDIATE 30 Intermediate 30 was prepared following an analogous procedure to the one described for the synthesis of intermediate 26, using intermediate 5 as starting material. Intermediate 30 (123.5 mg, quant.) was obtained as hydrochloride and as white solid.

PREPARATION OF INTERMEDIATE 31

Palladium hydroxide 20% on carbon (64 mg, 0.09 mmol) was added to a stirred solution of intermediate 6 (151.7 mg, 0.47 mmol) in MeOH (32 mL) at rt under nitrogen. Then, the nitrogen atmosphere was replaced by ¾ and the reaction mixture was stirred at rt for 18 h. Then, the mixture was filtered through celite® and the filtrate was concentrated in vacuo to yield intermediate 31 (104.1 mg, 95%) as a colourless oil. The crude product was used in the next step without further purification.

PREPARATION OF INTERMEDIATE 32

Hydrogen chloride (4 M in 1,4-dioxane, 2.64 mL, 10.55 mmol) was added to a solution of intermediate 12 (353 mg, 1.05 mmol) in 1,4-dioxane (10 mL) in a sealed tube at room temperature. The reaction mixture was stirred at rt for 48 h. The mixture was concentrated in vacuo and the crude was purified by ion exchange chromatography using an ISOLUTE SCX2 cartridge eluting first with MeOH and then with 7N soln. of N¾ in MeOH. The desired fractions were collected and concentrated in vacuo to afford intermediate 32 (205 mg, 82.9%) as a white solid.

PREPARATION OF INTERMEDIATE 33

Intermediate 33 was prepared following an analogous procedure to the one described for the synthesis of intermediate 26, using intermediate 14 as starting material. Intermediate 33 was obtained as hydrochloric acid salt (25.5 mg, quant.) as an oil, and was used in the following step without further purification.

PREPARATION OF INTERMEDIATE 34 . 2 HC1 1-34 Intermediate 34 was prepared following an analogous procedure to the one described for the synthesis of intermediate 26, using intermediate 15 as starting material. Intermediate 34 was obtained as hydrochloric acid salt as an oil (quant.) and was used in the following step without further purification.

PREPARATION OF INTERMEDIATE 35

Intermediate 35 was prepared following an analogous procedure to the one described for the synthesis of intermediate 26, using intermediate 16 as starting material. Intermediate 35 was obtained as hydrochloric acid salt (54 mg, quant.) as a colorless oil. PREPARATION OF INTERMEDIATE 36

Intermediate 36 was prepared following an analogous procedure to the one described for the synthesis of intermediate 27, using intermediate 17 as starting material. Intermediate 36 (331 mg, 49%) was obtained as a colorless oil. PREPARATION OF INTERMEDIATE 37

Intermediate 37 was prepared following an analogous procedure to the one described for the synthesis of intermediate 26, using intermediate 18 as starting material. Intermediate 37 was obtained as hydrochloric acid salt (20.3 mg, 72%) as a colorless oil.

PREPARATION OF INTERMEDIATE 38 1-38

To a stirred solution of intermediate 21 (318 mg, 0.86 mmol) in MeOH (20 mL) was added Pd/C (10%) (46 mg, 0.04 mmol) at rt under nitrogen atmosphere. Then, nitrogen atmosphere was replaced by ¾ and the reaction mixture was stirred at rt for 4h. The reaction mixture was filtered over a pad of celite® and was washed with MeOH/DCM mixture, then the solvents were removed in vacuo to yield intermediate 38 (204 mg, 98.9%) as a white solid. PREPARATION OF INTERMEDIATES 39 AND 40

The enantiomers of intermediate 38 (105 mg, 0.45 mmol) were separated by semipreparative SFC using Lux Amylose-1 column and an isocratic mode 20% [EtOH + 0.1% DEA] - 80% [CO2]. The desired fractions were collected and concentrated in vacuo to yield intermediate 39 (36 mg) and intermediate 40 (33 mg) both as colorless sticky solids. PREPARATION OF INTERMEDIATE 41

Thionyl chloride (6.51 mL, 89 mmol) was added to a solution of intermediate 42 (4.04 g, 22.3 mmol) in DCM (150 mL) at 0 °C. The mixture was stirred at rt for 12 h. Water (80 mL) was added and the mixture was extracted with DCM (80 mL x 3). The combined organic layers were dried (Na ₂ S0 ₄ ), filtered and evaporated in vacuo to yield crude intermediate 41 (3.53 g, 79%) as a brown oil that solidified upon standing.

PREPARATION OF INTERMEDIATE 42

Sodium borohydride (3.54 g, 94 mmol) was added to a solution of l-(2,3-dihydro- [l,4]dioxino[2,3-b]pyridin-6-yl)ethenone (CAS: 1254044-25-1; 4.5 g, 23.4 mmol) in EtOH (109 mL) at 0 °C. The mixture was stirred at rt for 10 min. Water was added and the mixture was extracted with DCM (80 mL x 3). The organic layers were combined, dried (NaiSCE), filtered and concentrated in vacuo to yield intermediate 42 (4.04 g, 95%) as a pale-yellow oil.

PREPARATION OF INTERMEDIATE 43

Intermediate 43 was prepared following an analogous procedure to the one described for the synthesis of intermediate 41 using intermediate 44 as starting material. Intermediate 43 was obtained in 80% yield as a brown oil.

PREPARATION OF INTERMEDIATE 44

Intermediate 44 was prepared following an analogous procedure to the one described for the synthesis of intermediate 42 using intermediate 45 as starting material. Intermediate 44 was obtained in 81% yield as a yellowish oil. PREPARATION OF INTERMEDIATE 45

To a mixture of intermediate 46 (900 mg, 4.75 mmol) in toluene (16.7 mL) were added Pd(PPh ₃ ) ₂ Cl ₂ (366 mg, 0.52 mmol) and tributyl(l-ethoxyvinyl)tin (2.25 mL, 6.65 mmol). The reaction mixture was stirred at 92 °C for 16 h. Then HC1 (2N, 1 mL) was added and the mixture was stirred at rt for 3 h. The mixture was neutralized with NaHCCb (sat.) and extracted with EtOAc. The organic layer was dried (MgSCL), filtered and concentrated in vacuo. The crude mixture was purified by flash column chromatography (S1O2, EtOAc in heptane, gradient from 0/100 to 100/0). The desired fractions were collected and concentrated in vacuo to afford intermediate 45 (563 mg, 60%) as a brown solid.

PREPARATION OF INTERMEDIATE 46

To a mixture of intermediate 47 (1.30 g, 5.77 mmol) in /-BuOH (32.6 mL) was added t- BuOK (777 mg, 6.92 mmol). The reaction mixture was heated at 90 °C for 1 h, cooled down and the solvent was removed in vacuo. The residue was diluted with water and EtOAc. The mixture was filtered through a pad of Celite® and washed with EtOAc.

The organic layer was washed with brine, dried (Na ₂ S0 ₄ ), filtered and concentrated in vacuo. The crude product was purified by flash column chromatography (S1O2, EtOAc in heptane, gradient from 0/100 to 50/50). The desired fractions were collected and concentrated in vacuo to yield intermediate 46 (470 mg, 43%) as a white solid.

PREPARATION OF INTERMEDIATE 47

(2-Bromoethoxy)-/er/-butyldimethylsilane (CAS: 86864-60-0; 1.51 mL, 7.06 mmol) was added to a stirred suspension of 2,6-dichloro-5-fluoropyridin-3-ol (CAS: 2228660- 663-5; 1.13 g, 6.21 mmol) and K ₂ CO ₃ (1.22 g, 8.82 mmol) in DMF (5.95 mL). The reaction mixture was stirred at 90 °C for 16 h, diluted with water and extracted with EtOAc (twice). The combined organic layers were dried (Na ₂ S0 ₄ ), filtered and the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography (S1O2, EtOAc in heptane, gradient from 0/100 to 50/50). The desired fractions were collected and the solvents were evaporated in vacuo to afford intermediate 47 (1.095 g, 78%) as white solid.

PREPARATION OF INTERMEDIATE 48

Intermediate 49 was added to a mixture of CFPCN (25 mL) and water (1.3 mL) containing three drops of indicator Sudan III (CAS: 85-86-9). The solution was cooled to 0 °C and a mixture of O ₃ /O ₂ was passed through the flask until the red color dissipated. The reaction was purged with N2 for 10 min. Then, the reaction was diluted with water and DCM. The organic layer was separated, dried (MgS0 ₄ ), filtered and the solvents removed in vacuo to yield intermediate 48 (411 mg, 93.2%) as a white solid.

PREPARATION OF INTERMEDIATE 49

Intermediate 46 (703 mg, 3.71 mmol), Pd(PPh3)4 (214 mg, 0.18 mmol), vinylboronic acid pinacol ester (CAS: 75927-49-0; 0.94 mL, 5.56 mmol) and sat. Na ₂ C0 ₃ (0.3 mL) were added to 1,4-dioxane (11 mL) in a sealed tube. The mixture was stirred at 125 °C for 90 min under microwave irradiation. The crude was neutralized with a sat. solution of NaHC0 ₃ and extracted with EtOAc, and the organic layer was separated, dried (MgS0 ₄ ), filtered and concentrated in vacuo. The crude product was purified by flash column chromatography (silica, MeOH in DCM 0/100 to 10/90). The desired fractions were collected and evaporated in vacuo to give intermediate 49 (436 mg, 64.9%) as a white solid.

PREPARATION OF INTERMEDIATE 50 Thionyl chloride (243.70 pL, 3.24 mmol) was added to a stirred solution of (7-fluoro-2, 3-dihydro-l,4-dioxino[2,3-b]pyridin-6-yl)-methanol (CAS: 1095276-15-5; 300 mg,

1.62 mmol), which was synthesized following the same procedure as described in patent W02009/001126, in DCM (6 mL) at 0 °C. The reaction mixture was stirred from 0 °C to rt for 3 h. Then, the solvent was evaporated in vacuo to yield intermediate 50 (320 mg, 96%) as a white solid, which was used for next reaction step without further purification.

PREPARATION OF INTERMEDIATE 51

Intermediate 51 was prepared following an analogous procedure to the one described for the synthesis of intermediate 48 using intermediate 52 as starting material. Intermediate 51 (340 mg, 41%) was obtained as an oil which became a light-yellow solid upon standing. PREPARATION OF INTERMEDIATE 52

A 10% aq. solution of K ₂ CO ₃ (30 mL) followed by vinylboronic acid pinacol ester (CAS: 75927-49-0; 1.48 mL, 8.71 mmol) and Pd(PPli3)4 (752 mg, 0.65 mmol) were added to a stirred solution of 6-chloro-2,3-dihydrofuro[2,3-b]pyridine (CAS: 161454- 93-9; 1.0 g, 6.31 mmol) in 1,4-dioxane (60 mL) in a round-bottom flask under a condenser and under N2. The mixture was stirred at 100 °C for 20 h. The mixture was treated with water and extracted with EtOAc. The organic layer was separated, dried (MgSCE), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (S1O2, EtOAc in heptane 0/100 to 20/80). The desired fractions were collected and concentrated in vacuo to yield intermediate 52 (820 mg, 88.2%) as a yellow oil.

PREPARATION OF INTERMEDIATE 53

A solution of BuLi (2.5 M in hexane; 2.87 mL, 7.19 mmol) was added a stirred solution of TMDA (CAS: 110-18-9, 816.5 pL, 5.39 mmol) in dry Et ₂ 0 (40 mL) at -20 °C, and the mixture was stirred at -20 °C for 1 h. The mixture was cooled down to -78 °C, and then intermediate 54 (500 mg, 3.59 mmol) diluted in dry Et ₂ 0 (5 mL) was added dropwise, and the mixture was stirred at -78 °C for 1 h. Then, L -formyl pi peri di ne (806.2 pL, 7.19 mmol) diluted in dry Et ₂ 0 (5 mL) was added dropwise to the previous mixture and the reaction mixture was stirred at -78 °C for 10 min. The reaction mixture was diluted with water at 0 °C and extracted with EtOAc. The organic layer was separated, washed with water, dried (MgSCE), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; EtOAc in heptane 0/100 to 40/60). The desired fractions were collected and concentrated in vacuo to yield intermediate 53 (213 mg, 35.5%) as a yellow solid.

PREPARATION OF INTERMEDIATE 54 A mixture of intermediate 55 (60 g, 361.1 mmol) in nitrobenzene (50 mL) was heated at 230 °C for 2 h. The reaction mixture was connected via cannula to a bubbler containing a sat. aq. soltn of NaOH (to trap the HCN released in the reaction). After the reaction was completed the crude was cooled and treated with an aq. solution of HC1 2N. The mixture was stirred for 1 h and the aq. layer was separated and then was treated with NaHC0 ₃ to basic pH, the crude was extracted with EtOAc (200ml x 3).

The organic layer was separated, dried over Na ₂ S0 ₄ , filtered and concentrated in vacuo. The crude product was purified by column chromatography (silica; petroleum ether/EtOAc 100/0 to 1/2). The pure fractions were collected, and the solvent was evaporated under vacuum to give intermediate 54 (46.6 g, 92.8%) as a white solid. PREPARATION OF INTERMEDIATE 55

A mixture of sodium hydride (25.7 g, 641.4 mmol) in THF (900 mL) was stirred at 0 °C under N2. Then, 3-butyn-l-ol (CAS: 927-74-2; 39.7 g, 566 mmol) was added dropwise and the mixture was stirred at 0 °C for 0.5 h. After that time, a solution of 2- chloro-5-fhioropyrimidine (CAS: 62802-42-0; 50 g, 377.3 mmol) in THF (100 mL) was added dropwise and the mixture was stirred at 0 °C. The reaction mixture was stirred at rt for 5 h. Then, water (1 L) was added and the mixture was extracted with DCM (1000 mL x 3). The organic layer was separated, dried over Na ₂ SC> ₄ filtered and concentrated in vacuo to give the crude product as yellow oil. The crude product was purified by column chromatography (silica; petroleum ether/EtOAc 100/0 to 1/1). The pure fractions were collected and the solvent was evaporated under vacuum to give the desired product intermediate 55 (37.5 g, 56.7%) as a white solid. PREPARATION OF INTERMEDIATE 56

Mn0 ₂ (7.48 g, 86.0 mmol) was added to a stirred suspension of intermediate 57 (7.55 g, 36.0 mmol) in 1,4-dioxane (50 mL). The mixture was stirred at 80 °C for 16 h and then filtered through a Celite® pad. The filtrate was evaporated in vacuo and the residue was purified by flash column chromatography (S1O2; EtOAc in petroleum ether, gradient from 0/100 to 50/50). The desired fractions were collected and concentrated in vacuo to yield intermediate 56 (2.0 g, 65%) as a yellow solid. PREPARATION OF INTERMEDIATE 57

NaBFE (6.81 mL, 180.0 mmol) was added to a stirred suspension of intermediate 58 (7.55 g, 36.0 mmol) in THF (60 mL). The mixture was stirred at 25 °C for 5 h and then a saturated NH ₄ CI solution (100 mL) was added. The mixture was extracted with DCM and the organic layer was separated, dried (Na ₂ S0 ₄ ), filtered and the solvents were evaporated in vacuo to yield intermediate 57 as a yellow solid (3.1 g, 51%).

PREPARATION OF INTERMEDIATE 58

Phosphorus pentasulfide (13.7 g, 61.5 mmol) was added to a suspension of intermediate 59 (14.0 g, 51.3 mmol) in THF (200 mL) under N2. The mixture was stirred at 25 °C for

16 h and then at 70 °C for 48 h. Then, the solvent was evaporated in vacuo and the residue purified by flash column chromatography (S1O2; EtOAc in petroleum ether, gradient from 0/100 to 50/50). The desired fractions were collected and concentrated in vacuo to yield intermediate 58 as a yellow solid (7.5 g, 69%). PREPARATION OF INTERMEDIATE 59 Acetic anhydride (13.2 g, 129.8 mmol) was added to a stirred mixture of methyl 6- amino-5-bromopyridine-2-carboxylate (CAS: 178876-82-9; 30 g, 129.8 mmol) in toluene (600 mL) under N2. The mixture was stirred at 100 °C for 36 h and then the solvent evaporated in vacuo. The residue was purified by flash column chromatography (S1O2; EtOAc in petroleum ether, gradient from 0/100 to 50/50). The desired fractions were collected and concentrated in vacuo to yield intermediate 59 as a white solid (14.0 g, 40%).

PREPARATION OF INTERMEDIATE 60 Intermediate 60 was prepared following an analogous procedure to the one described for the synthesis of intermediate 48 using intermediate 61 as starting material. Intermediate 60 (498 mg, 94.7%) was obtained as a yellow solid.

PREPARATION OF INTERMEDIATE 61 Intermediate 61 was prepared following an analogous procedure to the one described for the synthesis of intermediate 52 using intermediate 62 as starting material. Intermediate 61 (570.8 mg, 80.7%) was obtained as an orange solid.

PREPARATION OF INTERMEDIATE 62 A mixture of intermediate 63 (1.93 g, 8.92 mmol), tetrabutylammonium bromide (4.31 g, 13.38 mmol) and molecular sieves 4 A in DCM (80 mL) was stirred at rt for 10 min. Then, />-toluenesulfonic anhydride (4.37 g, 13.38 mmol) was added and the mixture was stirred at rt for 20 h under N2. The reaction mixture was filtered off and the filtrate was evaporated in vacuo. The crude was purified by flash column chromatography (S1O2; DCM). The desired fractions were collected and concentrated to give intermediate 62 as a white solid (907 mg, 41.2%). PREPARATION OF INTERMEDIATE 63 w-Chloroperbenzoic acid (1.13 g, 6.42 mmol) was added to a mixture of intermediate 64 (0.72 g, 4.28 mmol) in DCM (24 mL). The mixture was stirred at rt for 16 h and then more w-chloroperbenzoic acid (1.13 g, 6.42 mmol) was added. The mixture was stirred at rt for a further 3 days and then water was added, and the mixture extracted with DCM. The organic layer was separated, dried (MgSCri), filtered and the solvents were evaporated in vacuo. The residue was taken up into DCM and the solid formed was filtered off and discarded. The filtrate was evaporated in vacuo and the residue purified by flash column chromatography (SiCk; MeOH in DCM, gradient from 0/100 to 10/90). The desired fractions were collected and concentrated in vacuo to yield intermediate 63 as a white solid (0.51 g, 65%).

PREPARATION OF INTERMEDIATE 64 Phosphorus pentasulfide (1.70 g, 7.67 mmol) was added to a suspension of intermediate 65 (1.38 g, 5.90 mmol) in THF (32.2 mL). The mixture was stirred at rt for 16 h and an additional amount of phosphorus pentasulfide (0.39 g, 1.77 mmol) was added. The mixture was stirred at rt for another 16 h and then CS2CO3 (3.08 g, 9.44 mmol) was added. The mixture was stirred at 70 °C for 16 h and then additional quantity of CS2CO3 (3.08 g, 9.44 mmol) was added. The mixture was stirred at 70 °C for a further 16 h and then water was added. The mixture was extracted with EtOAc and the organic layer was separated, dried (Na ₂ SC> ₄ ), filtered and the solvents were evaporated in vacuo. The residue was purified by flash column chromatography (S1O2; EtOAc in heptane, gradient from 0/100 to 60/40). The desired fractions were collected and concentrated in vacuo to yield intermediate 64 as a pale-orange solid (0.78 g, 78%).

PREPARATION OF INTERMEDIATE 65 Intermediate 65 was prepared following an analogous procedure to the one described for the synthesis of intermediate 59 using 2-amino-3-bromo-5-fluoropyridine (CAS: 869557-43-7) as starting material. Intermediate 65 was obtained as a yellow solid in quantitative yield. PREPARATION OF FINAL COMPOUNDS

El. PREPARATION OF PRODUCT 1

Sodium triacetoxyborohydride (142.3 mg, 0.67 mmol) was added to a stirred suspension of intermediate 26 (49.3 mg, 0.22 mmol) and 2,3-dihydro-[l,4]dioxino[2,3- b]pyridine-6-carbaldehyde (CAS: 615568-24-6; 40.65 mg, 0.25 mmol) in DCM (1.5 mL). The reaction mixture was stirred at rt for 24 h. The mixture was diluted with a sat. aq. sol. of NaHC0 ₃ and extracted with DCM. The organic layer was separated, dried (MgS0 ₄ ), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; 100% DCM). The desired fractions were collected and concentrated in vacuo. The residue was re-purified by RP HPLC

(stationary phase: Cl 8 XBridge 30 x 100 mm 5 mm), (mobile phase: gradient from 80% lOmM NH ₄ HCO ₃ /NH ₄ OH pH=9 solution in water, 20% CH ₃ CN to 60% lOmM NH ₄ HCO ₃ /NH ₄ OH pH=9 solution in water, 40% CH ₃ CN), yielding product 1 (14.9 mg, 18%) as a colorless oil. E2. PREPARATION OF PRODUCT 2

Product 2 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 27 (50 mg, 0.23 mmol) and 2,3-dihydro-[l,4] dioxino[2,3-b]pyridine-6-carbaldehyde (CAS: 615568-24-6; 41.23 mg, 0.25 mmol) as starting materials. Product 2 was obtained as a colorless oil (20 mg, 23.8%).

E3. PREPARATION OF PRODUCT 3 Product 3 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 26 (75 mg, 0.34 mmol) and intermediate 48 (64.06 mg, 0.34 mmol) as starting materials. Product 3 was obtained as a white sticky solid (103 mg, 78.1%).

E4. PREPARATION OF PRODUCT 4

Product 4 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 26 (75 mg, 0.34 mmol) and intermediate 51 (64.06 mg, 0.34 mmol) as starting materials. After the RP HPLC purification, product 4 was obtained as a colorless oil, which was treated with 2 equivalents of citric acid in a mixture of Et ₂ 0/l,4-dioxane (1 :2) to yield product 4 in its di-citrate form as a light yellow solid (130 mg, 51,8%).

E5. PREPARATION OF PRODUCT 5

Product 5 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 26 (49.3 mg, 0.22 mmol) and intermediate 56 (44.35 mg, 0.25 mmol) as starting materials. Product 5 was obtained as a colorless oil (12.6 mg, 14.7%).

E6. PREPARATION OF PRODUCT 6

Product 6 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 26 (75 mg, 0.34 mmol) and intermediate 60 (73.5 mg, 0.37 mmol) as starting materials. Product 6 was obtained as a light-yellow solid (92 mg, 67.5%). E7. PREPARATION OF PRODUCT 7

Product 7 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 26 (75 mg, 0.34 mmol) and intermediate 53 (64.1 mg, 0.34 mmol) as starting materials. Product 7 was obtained as a beige solid (25 mg, 19.8%).

E8. PREPARATION OF PRODUCT 8

Product 8 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 27 (46.7 mg, 0.21 mmol) and intermediate 56 (41.55 mg, 0.23 mmol) as starting materials. Product 8 was obtained as a colorless oil (14.6 mg, 18%).

E9. PREPARATION OF PRODUCT 9

Product 9 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 31 (208.2 mg, 0.89 mmol) and intermediate 53 (135 mg, 0.81 mmol) as starting materials. Product 9 was obtained as a brown oil (10 mg, 3.2%).

E10. PREPARATION OF PRODUCT 10 . 2 HC1

Product 10 was prepared following an analogous procedure to the one described for the synthesis of product 1, using intermediate 32 (100 mg, 0.43 mmol) and intermediate 48 (78.2 mg, 0.43 mmol) as starting materials. After the RP HPLC purification, product 10 was obtained as a light-yellow oil, which was dissolved in Et ₂ 0 and treated with a 2N HC1 sol. in Et ₂ 0 to yield product 10 in its di-hydrochloride salt form as a white solid (35 mg, 19.1%).

Ell. PREPARATION OF PRODUCT 11

Titanium(IV) isopropoxide (0.22 mL, 0.75 mmol) was added to a solution of intermediate 29 (102.5 mg, 0.5 mmol) and intermediate 53 (83 mg, 0.5 mmol) in DCM (2.5 mL) under N2. The mixture was stirred at rt for 6 h. Then, sodium triacetoxyborohydride (263.3 mg, 1.24 mmol) was added at 0 °C and the reaction mixture was stirred at rt for 16 h. After this time, H2O was added and the mixture was extracted with DCM. The organic layer was separated, dried, filtered and solvents concentrated in vacuo. The crude was purified by flash column chromatography (silica; MeOH in DCM 0/100 to 5/95). The desired fractions were collected and solvents concentrated in vacuo to give product 11 as a yellow oil (112 mg, 63%). This residue was treated with citric acid (107.5 mg, 0.56 mmol) in a mixture of Et ₂ 0 (5.3 mL) and 1,4-dioxane (1.8 mL) for 1 h, and the solid that precipitated was filtered off, washed with Et20 and dried to yield product 11 in its di-citrate form as a white solid (161 mg, 48.9%).

E12. PREPARATION OF PRODUCT 12

Product 12 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 30 (144 mg, 0.56 mmol) and intermediate 53 (93.7 mg, 0.56 mmol) as starting materials, and in the presence of Et3N (0.23 mL, 1.68 mmol). The residue obtained after the column chromatography was further purified by RP HPLC (stationary phase: Cl 8 XBridge 50 x 100 mm 5 pm), (mobile phase: gradient from 55% NH4HCO3 0.25% solution in water, 45% CH3CN to 25% NH4HCO3 0.25% solution in water, 75% CH3CN), yielding product 12 as an oil. The crude was treated with citric acid in an analogous manner to the one described for product 11, to yield product 12 in its di-citrate form as a white solid (105 mg, 28%). El 3. PREPARATION OF PRODUCT 13

Product 13 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 32 (49 mg, 0.21 mmol) and intermediate 56 (41.4 mg, 0.23 mmol) as starting materials. The crude was purified by RP HPLC

(stationary phase: C18 XBridge 30 x 100 nm 5 pm), (mobile phase: gradient from 74% 0.1% NH4HCO3/NH4OH pH = 9 solution in water, 26% CH3CN to 58 % 0.1% NH4HCO3/NH4OH pH = 9 solution in water, 42% CH3CN), yielding a residue which was treated with DIPE to give product 13 as a white solid (34.7 mg, 41.8%). E14. PREPARATION OF PRODUCT 14

Product 14 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 34 (21.8 mg, 0.099 mmol) and intermediate 48 (18.12 mg, 0.099 mmol) as starting materials, and in the presence of Et3N (41.2 pL, 0.30 mmol). Product 14 was purified by flash column chromatography (silica; MeOH in DCM 0/100 to 5/95) yielding 15.6 mg (41%) as a colorless oil.

El 5. PREPARATION OF PRODUCT 15

Product 15 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 35 (54.7 mg, 0.25 mmol) and intermediate 48 (45.27 mg, 0.25 mmol) as starting materials, and in the presence of Et3N (0.10 mL, 0.74 mmol). The residue obtained after the column chromatography was further purified by RP HPLC (stationary phase: Cl 8 XBridge 50 x 100 mm 5 pm), (mobile phase: gradient from 90% NH ₄ HCO ₃ 0.25% solution in water, 10% CEPCN to 60% NH4HCO3 0.25% solution in water, 40% CH3CN), yielding product 15 as a colorless oil (22.9 mg, 24%).

E16. PREPARATION OF PRODUCT 16 Product 16 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 36 (25 mg, 0.12 mmol) and intermediate 56 (23.45 mg, 0.13 mmol) as starting materials. The residue obtained after the column chromatography was further purified by RP HPLC (stationary phase: Cl 8 XBridge 50 x 100 mm 5 pm), (mobile phase: gradient from 74% 0.1% NH4HCO3/NH4OH pH=9 solution in water, 26% CH3CN to 58% 0.1% NH4HCO3/NH4OH pH=9 solution in water, 42% CH3CN), yielding product 16 as a yellow oil (16.3 mg, 37%).

E17. PREPARATION OF PRODUCT 17

Product 17 was prepared following an analogous procedure to the one described for the synthesis of product 11, using intermediate 37 (20.3 mg, 0.081 mmol) and intermediate 48 (14.85 mg, 0.081 mmol) as starting materials, and in the presence of Et3N (33.81 pL, 0.24 mmol). Product 17 was purified by flash column chromatography (silica; MeOH in DCM 0/100 to 5/95) yielding 13.9 mg (41%) as a colorless oil.

El 8. PREPARATION OF PRODUCTS 18 AND 19

Intermediate 43 (54.33 mg, 0.25 mmol) and K2CO3 (94.1 mg, 0.68 mmol) were added to a stirred solution of intermediate 26 (50 mg, 0.23 mmol) in ACN (1.12 mL). The mixture was stirred at 80 °C for 18 h. Water was added, and the mixture was extracted with EtOAc. The organic phase was separated, dried (MgS0 ₄ ), filtered and evaporated under vacuum. The crude product was purified by flash column chromatography (silica; MeOH in DCM 0/100 to 10/90). The desired fractions were collected and concentrated in vacuo to yield a mixture of stereoisomers. The mixture was purified by RP HPLC (stationary phase: Cl 8 XBridge 30 x 100 mm 5 pum), (mobile phase: gradient from 67% 0.1% NH ₄ HCO ₃ /NH ₄ OH pH 9 solution in water, 33% CH ₃ CN to 50% 0.1% NH ₄ HCO ₃ /NH ₄ OH pH 9 solution in water, 50% CH ₃ CN). The desired fractions were collected and concentrated in vacuo to afford product 18 as an oil (containing 11% of an impurity) and product 19 as a yellow sticky solid (34 mg, 37.3%). Product 18 was again purified by RP HPLC (stationary phase: C18 XBridge 30 x 100 mm 5 pm), (mobile phase: gradient from 67% 0.1% NH4HCO3/NH4OH pH=9 solution in water, 33% CH3CN to 50% 0.1% NH4HCO3/NH4OH pH=9 solution in water, 50% CH3CN). The desired fractions were collected and concentrated in vacuo to afford product 18 (48 mg, 52.7%) as an oil which solidified upon standing. E19. PREPARATION OF PRODUCTS 20, 21 AND 22

Product 20 was prepared following an analogous procedure to the one described for the synthesis of products 18 and 19, using intermediate 38 (98.5 mg, 0.38 mmol) and intermediate 50 (70 mg, 0.35 mmol) as starting materials. Upon purification by flash column chromatography (silica; MeOH in DCM 0/100 to 4.5/95.5) product 20 was obtained as a yellow sticky solid (139 mg, 99.7%).

130 mg of product 20 (mixture of enantiomers) were subjected to semipreparative SFC separation using Lux Amylose-1 column and an isocratic mode 10% [MeOH + 0.1% DEA] - 90% [C02] The desired fractions were collected and concentrated in vacuo to yield products 21 and 22 as colorless sticky solids. Both compounds were independently taken into DCM and treated with 1.05 equiv. of 4N HC1 in dioxane, and the solvents were evaporated in vacuo. The crude residues were triturated with Et ₂ 0, filtered and dried, to yield product 21 as a white solid (35 mg, 24.7%) and product 22 as a white solid (30 mg, 21.1%) both as hydrochloric acid salts.

Product 23 was prepared following an analogous procedure to the one described in example E18, using intermediate 39 (43.5 mg, 0.19 mmol) and intermediate 43 (52.5 mg, 0.24 mmol) as starting materials. Upon purification by flash column chromatography (silica; MeOH in DCM 0/100 to 10/90) product 23 was obtained as a brown sticky solid (40.2 mg, 51.5%).

35 mg of product 23 were subjected to RP HPLC (stationary phase: C18 XBridge 30 x 100 mm 5 pum), (mobile phase: gradient from 72% [65mMNH ₄ 0Ac + ACN (90:10)] - 28% [ACN: MeOH 1:1] to 36% [65mM H ₄ OAc + ACN (90:10)] - 64% [ACN: MeOH 1:1]). The desired fractions were collected and concentrated in vacuo to yield products 24 (10 mg) and 25 (12 mg) as yellow oils.

Both oily residues were independently taken into DCM and treated with 1 equiv. of 4N HC1 in dioxane (6 pL and 7.5 pL respectively), and the solvents were evaporated in vacuo. The crude residues were triturated with Et ₂ 0 to yield product 24 as a beige sticky solid (7.8 mg, 9.2%) and product 25 as a beige solid (12.2 mg, 14.1%) both as hydrochloric acid salts. E21. PREPARATION OF PRODUCTS 26, 27 AND 28

Products 26, 27 and 28 were prepared following an analogous procedure to the one described in example E20 for the synthesis of products 23, 24 and 25, using intermediate 40 (33 mg, 0.14 mmol) and intermediate 43 (39.84 mg, 0.18 mmol) as starting materials. Product 26 was obtained as a yellow sticky solid (40 mg, 58%).

34 mg of product 26 were used for isolation and purification of compounds 27 and 28 in an analogous manner to the one described in example E20. Hence, product 27 was obtained as a beige solid (12.6 mg, HC1 salt, 19.2%), and product 28 was obtained also as a beige solid (17 mg, HC1 salt, 26.4%). E22. PREPARATION OF PRODUCT 29

2,3-Dihydro-[l,4]dioxino[2,3-b]pyridine-6-carbaldehyde (CAS: 615568-24-6; 90 mg, 0.54 mmol) and titanium(IV) isopropoxide (398.6 pL, 1.36 mmol) were added to a stirred solution of intermediate 28 (100 mg, 0.45 mmol) in DCM (2.5 mL) at rt and under N _2. The mixture was stirred at rt for 16 h. Then, the mixture was cooled at 0 °C and methylmagnesium bromide (1.4 M in THF, 1.62 mL, 2.27 mmol) was added dropwise. The reaction mixture was stirred at this temperature for 25 min and at rt for 2 h. The mixture was treated with sat NH ₄ CI aq. solution, filtered through celite® and washed with DCM, and then washed with H2O and extracted with DCM. The organic layer was separated, dried (Na ₂ S0 ₄ ), filtered and the solvent was evaporated in vacuo. The crude product was purified by flash column chromatography (S1O2; MeOH in DCM 0/100 to 4/96). The desired fractions were collected and concentrated in vacuo, and the residue was triturated with Et ₂ 0 to yield product 29 as a sticky solid (111 mg, 63.8%).

Products 30 and 31 were prepared following an analogous procedure to the one described in example E22, using intermediate 26 (49.3 mg, 0.22 mmol) and intermediate 56 (48.4 mg, 0.27 mmol) as starting materials. After the column chromatography, the residue was purified by RP HPLC (stationary phase: Cl 8 XBridge

30 x 100 mm 5 mm), (mobile phase: Gradient from 80% lOmM NH ₄ HCO ₃ /NH ₄ OH pH=9 solution in water, 20% ACN to 0% lOmM NH ₄ HCO ₃ /NH ₄ OH pH=9 solution in water, 100% ACN), yielding product 30 as a colorless oil (4.5 mg, 5.1%) and product

31 as a brown sticky solid (14.7 mg, 16.6%).

E24. PREPARATION OF PRODUCTS 32 AND 33

Products 32 and 33 were prepared following an analogous procedure to the one described in example E23, using intermediate 27 (46.7 mg, 0.21 mmol) and intermediate 56 (45.83 mg, 0.25 mmol) as starting materials. RP HPLC purification afforded product 32 (4.4 mg, 5.2%) and product 33 (4.7 mg, 5.6%) as oils.

The following compounds were prepared following the methods exemplified in the Experimental Part. In case no salt form is indicated, the compound was obtained as a free base. Έc. No.’ refers to the Example number according to which protocol the compound was synthesized. ‘Co. No.’ means compound number. The values of salt stoichiometry or acid content in the compounds as provided herein, are those obtained experimentally. The content of acid reported herein was determined by 'H NMR integration and/or elemental analysis. TABLE 1

ANALYTICAL PART

MELTING POINTS

Values are peak values and are obtained with experimental uncertainties that are commonly associated with this analytical method.

DSC823e (A): For a number of compounds, melting points were determined with a DSC823e (Mettler-Toledo) apparatus. Melting points were measured with a temperature gradient of 10 °C/minute. Maximum temperature was 300 °C. Values are peak values (A). Mettler Toledo MP50 (B) For a number of compounds, melting points were determined in open capillary tubes on a Mettler FP 81HT / FP90 apparatus. Melting points were measured with a temperature gradient of 1, 3, 5 or 10 °C/minute. Maximum temperature was 300 °C. The melting point was read from a digital display (B).

LCMS

GENERAL PROCEDURE

The High Performance Liquid Chromatography (HPLC) measurement was performed using a LC pump, a diode-array (DAD) or a UV detector and a column as specified in the respective methods. If necessary, additional detectors were included (see table of methods below).

Flow from the column was brought to the Mass Spectrometer (MS) which was configured with an atmospheric pressure ion source. It is within the knowledge of the skilled person to set the tune parameters (e.g. scanning range, dwell time...) in order to obtain ions allowing the identification of the compound’s nominal monoisotopic molecular weight (MW) and/or exact mass monoisotopic molecular weight. Data acquisition was performed with appropriate software.

Compounds are described by their experimental retention times (R _t ) and ions. If not specified differently in the table of data, the reported molecular ion corresponds to the [M+H] ⁺ (protonated molecule) and/or [M-H] (deprotonated molecule). All results were obtained with experimental uncertainties that are commonly associated with the method used.

Hereinafter, “SQD” Single Quadrupole Detector, “MSD” Mass Selective Detector, “QTOF” Quadrupole-Time of Flight, “rt” room temperature, “BEH” bridged ethylsiloxane/silica hybrid, HSS” High Strength Silica, “CSH” charged surface hybrid, “UPLC” Ultra Performance Liquid Chromatography, “DAD” Diode Array Detector. TABLE 2. LC-MS Methods (Flow expressed in mL/min; column temperature (T) in °C;

Run time in min). TABLE 3. Analytical data - melting point (M.p.) and LCMS. “n.m.” means that was not measured, “n.d.” means that could not be determined. [M+H] ⁺ means the protonated mass of the free base of the compound, [M-H] means the deprotonated mass of the free base of the compound or the type of adduct specified [M+CH ₃ COO] ). R _t means retention time (in min). For some compounds, exact mass was determined.

OPTICAL ROTATIONS

Optical rotations were measured on a Perkin-Elmer 341 polarimeter with a sodium lamp and reported as follows: [a]° (l, c g/lOOml, solvent, T °C). [a] _l ^T = (100a) / (lx c): where / is the path length in dm and c is the concentration in g/100 ml for a sample at a temperature T (°C) and a wavelength l (in nm). If the wavelength of light used is 589 nm (the sodium D line), then the symbol D might be used instead. The sign of the rotation (+ or -) should always be given. When using this equation, the concentration and solvent are always provided in parentheses after the rotation. The rotation is reported using degrees and no units of concentration are given (it is assumed to be g/100 mL). ABLE 4. Optical Rotation data.

NMR

For a number of compounds, 'H NMR spectra were recorded on a Bruker AV III HD spectrometer operating at 400 MHz, on a Bruker Avance NEO operating at 500 MHz, or on a Bruker Avance NEO spectrometer operating at 400 MHz, using CHLOROFORM-r/ (deuterated chloroform, CDCb) or DMSO-rL (deuterated DMSO, dimethyl-d6 sulfoxide) as solvent. Chemical shifts (d) are reported in parts per million (ppm) relative to tetramethylsilane (TMS), which was used as internal standard.

PHARMACOLOGICAL EXAMPLES

1) OGA - BIOCHEMICAL ASSAY

The assay is based on the inhibition of the hydrolysis of fluorescein mono-B-D-N- Acetyl-Glucosamine (FM-GlcNAc) (Mariappa et al. 2015, Biochem J 470:255) by the recombinant human Meningioma Expressed Antigen 5 (MGEA5), also referred to as O-GlcNAcase (OGA). The hydrolysis FM-GlcNAc (Marker Gene technologies, cat # M1485) results in the formation of B-D-N-glucosamineacetate and fluorescein. The fluorescence of the latter can be measured at excitation wavelength 485 nm and emission wavelength 538nm. An increase in enzyme activity results in an increase in fluorescence signal. Full length OGA enzyme was purchased at OriGene (cat # TP322411). The enzyme was stored in 25 mM Tris.HCl, pH 7.3, 100 mM glycine, 10% glycerol at -20 °C. Thiamet G and GlcNAcStatin were tested as reference compounds (Yuzwa et al. 2008 Nature Chemical Biology 4:483; Yuzwa et al. 2012 Nature Chemical Biology 8:393). The assay was performed in 200mM Citrate/phosphate buffer supplemented with 0.005% Tween-20. 35.6 g Na ₂ HP0 ₄ 2 ¾0 (Sigma, # C0759) were dissolved in 1 L water to obtain a 200 mM solution. 19.2 g citric acid (Merck, # 1.06580) was dissolved in 1 L water to obtain a 100 mM solution. pH of the sodiumphosphate solution was adjusted with the citric acid solution to 7.2. The buffer to stop the reaction consists of a 500 mM Carbonate buffer, pH 11.0. 734 mg

FM-GlcNAc were dissolved in 5.48 mL DMSO to obtain a 250 mM solution and was stored at -20 °C. OGA was used at a 2nM concentration and FM-GlcNAc at a lOOuM final concentration. Dilutions were prepared in assay buffer.

50 nl of a compound dissolved in DMSO was dispensed on Black Proxiplate TM 384 Plus Assay plates (Perkin Elmer, #6008269) and 3 pi fl-OGA enzyme mix added subsequently. Plates were pre-incubated for 60 min at room temperature and then 2 mΐ FM-GlcNAc substrate mix added. Final DMSO concentrations did not exceed 1%. Plates were briefly centrifuged for 1 min at 1000 rpm and incubate at room temperature for 6 h. To stop the reaction 5 mΐ STOP buffer were added and plates centrifuge again 1 min at lOOOrpm. Fluorescence was quantified in the Thermo Scientific Fluoroskan Ascent or the PerkinElmer EnVision with excitation wavelength 485 nm and emission wavelength 538 nm.

For analysis a best-fit curve is fitted by a minimum sum of squares method. From this an IC50 value and Hill coefficient was obtained. High control (no inhibitor) and low control (saturating concentrations of standard inhibitor) were used to define the minimum and maximum values.

2) OGA - CELLULAR ASSAY

HEK293 cells inducible for P301L mutant human Tau (isoform 2N4R) were established at Janssen. Thiamet-G was used for both plate validation (high control) and as reference compound (reference EC50 assay validation). OGA inhibition is evaluated through the immunocytochemical (ICC) detection of O-GlcNAcylated proteins by the use of a monoclonal antibody (CTD110.6; Cell Signaling, #9875) detecting O- GlcNAcylated residues as previously described (Dorfmueller et al. 2010 Chemistry & biology, 17:1250). Inhibition of OGA will result in an increase of O- GlcNAcylated protein levels resulting in an increased signal in the experiment. Cell nuclei are stained with Hoechst to give a cell culture quality control and a rough estimate of immediate compounds toxicity, if any. ICC pictures are imaged with a Perkin Elmer Opera Phenix plate microscope and quantified with the provided software Perkin Elmer Harmony 4.1.

Cells were propagated in DMEM high Glucose (Sigma, #D5796) following standard procedures. 2 days before the cell assay cells are split, counted and seeded in Poly-D- Lysine (PDL) coated 96-wells (Greiner, #655946) plate at a cell density of 12,000 cells per cm ² (4,000 cells per well) in IOOmI of Assay Medium (Low Glucose medium is used to reduce basal levels of GlcNAcylation) (Park et al. 2014 The Journal of biological chemistry 289:13519). At the day of compound test medium from assay plates was removed and replenished with 90m1 of fresh Assay Medium. 10m1 of compounds at a lOfold final concentration were added to the wells. Plates were centrifuged shortly before incubation in the cell incubator for 6 hours. DMSO concentration was set to 0.2%. Medium is discarded by applying vacuum. For staining of cells medium was removed and cells washed once with 100 pi D-PBS (Sigma, #D8537). From next step onwards unless other stated assay volume was always 50m1 and incubation was performed without agitation and at room temperature. Cells were fixed in 50m1 of a 4% paraformaldehyde (PFA, Alpha aesar, # 043368) PBS solution for 15 minutes at room temperature. The PFA PBS solution was then discarded and cells washed once in lOmM Tris Buffer (LifeTechnologies, # 15567-027), 150mMNaCl (LifeTechnologies, #24740-0110, 0.1% Triton X (Alpha aesar, # A16046), pH 7.5 (ICC buffer) before being permeabilized in same buffer for 10 minutes. Samples are subsequently blocked in ICC containing 5% goat serum (Sigma, #G9023) for 45-60 minutes at room temperature. Samples were then incubated with primary antibody (1/1000 from commercial provider, see above) at 4°C overnight and subsequently washed 3 times for 5 minutes in ICC buffer. Samples were incubated with secondary fluorescent antibody (1/500 dilution, Lifetechnologies, # A-21042) and nuclei stained with Hoechst 33342 at a final concentration of lpg/ml in ICC (Lifetechnologies, # H3570) for 1 hour. Before analysis samples were washed 2 times manually for 5 minutes in ICC base buffer.

Imaging is performed using Perkin Elmer Phenix Opera using a water 20x objective and recording 9 fields per well. Intensity readout at 488nm is used as a measure of O-GlcNAcylation level of total proteins in wells. To assess potential toxicity of compounds nuclei were counted using the Hoechst staining. ICso-values are calculated using parametric non-linear regression model fitting. As a maximum inhibition Thiamet G at a 200uM concentration is present on each plate. In addition, a concentration response of Thiamet G is calculated on each plate.

TABLE 6. Results in the biochemical and cellular assays.