DERIVATIVE PRODRUGS

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Application Serial No. 62/081,515, the disclosure of which is incorporated by reference herein in its entirety for all purposes.

BACKGROUND OF THE INVENTION

[0002] Pulmonary hypertension (PH) is characterized by an abnormally high blood pressure in the lung vasculature. It is a progressive, lethal disease that leads to heart failure and can occur in the pulmonary artery, pulmonary vein, or pulmonary capillaries. Symptomatically patients experience shortness of breath, dizziness, fainting, and other symptoms, all of which are made worse by exertion. There are multiple causes, and can be of unknown origin, idiopathic, and can lead to hypertension in other systems, for example, portopulmonary hypertension in which patients have both portal and pulmonary hypertension.

[0003] Pulmonary hypertension has been classified into five groups by the World Health Organization (WHO). Group I is called pulmonary arterial hypertension (PAH), and includes PAH that has no known cause (idiopathic), inherited PAH (i.e., familial PAH or FPAH), PAH that is caused by drugs or toxins, and PAH caused by conditions such as connective tissue diseases, HIV infection, liver disease, and congenital heart disease. Group II pulmonary hypertension is characterized as pulmonary hypertension associated with left heart disease. Group III pulmonary hypertension is characterized as PH associated with lung diseases, such as chronic obstructive pulmonary disease and interstitial lung diseases, as well as PH associated with sleep-related breathing disorders (e.g., sleep apnea). Group IV PH is PH due to chronic thrombotic and/or embolic disease, e.g., PH caused by blood clots in the lungs or blood clotting disorders. Group V includes PH caused by other disorders or conditions, e.g., blood disorders (e.g., polycythemia vera, essential thrombocythemia), systemic disorders (e.g., sarcoidosis, vasculitis), metabolic disorders (e.g., thyroid disease, glycogen storage disease).

[0004] Pulmonary arterial hypertension (PAH) afflicts approximately 200,000 people globally with approximately 30,000-40,000 of those patients in the United States. PAH patients experience constriction of pulmonary arteries which leads to high pulmonary arterial pressures, making it difficult for the heart to pump blood to the lungs. Patients suffer from shortness of breath and fatigue which often severely limits the ability to perform physical activity.

[0005] The New York Heart Association (NYHA) has categorized PAH patients into four functional classes, used to rate the severity of the disease. Class I PAH patients as categorized by the NYHA, do not have a limitation of physical activity, as ordinary physical activity does not cause undue dyspnoea or fatigue, chest pain, or near syncope. Treatment is not needed for class I PAH patients. Class II PAH patients as categorized by the NYHA have a slight limitation on physical activity. These patients are comfortable at rest, but ordinary physical activity causes undue dyspnoea or fatigue, chest pain or near syncope. Class III PAH patients as categorized by the NYHA have a marked limitation of physical activity. Although comfortable at rest, class III PAH patients experience undue dyspnoea or fatigue, chest pain or near syncope as a result of less than ordinary physical activity. Class IV PAH patients as categorized by the NYHA are unable to carry out any physical activity without symptoms. Class IV PAH patients might experience dyspnoea and/or fatigue at rest, and discomfort is increased by any physical activity. Signs of right heart failure are often manifested by class TV PAH patients.

[0006] Patients with PAH are treated with an endothelin receptor antagonist (ERA), phosphodiesterase type 5 (PDE-5) inhibitor, a guanylate cyclase stimulator, a prostanoid (e.g., prostacyclin), or a combination thereof. ERAs include abrisentan (Letairis®), sitaxentan, bosentan (Tracleer®), and macitentan (Opsumit®). PDE-5 inhibitors indicated for the treatment of PAH include sildenafil (Revatio®), tadalafil (Adcirca®). Prostanoids indicated for the treatment of PAH include iloprost, epoprosentol and treprostinil (Remodulin®, Tyvaso®). The one approved guanylate cyclase stimulator is riociguat (Adempas®). Additionally, patients are often treated with combinations of the aforementioned compounds.

[0007] Portopulmonary hypertension is defined by the coexistence of portal and pulmonary hypertension, and is a serious complication of liver disease. The diagnosis of portopulmonary hypertension is based on hemodynamic criteria: (1) portal hypertension and/or liver disease (clinical diagnosis-ascites/varices/splenomegaly), (2) mean pulmonary artery pressure > 25 mmHg at rest, (3) pulmonary vascular resistance > 240 dynes s/cm ⁵ , (4) pulmonary artery occlusion pressure < 15mmHg or transpulmonary gradient > 12 mmHg. PPH is a serious complication of liver disease, and is present in 0.25 to 4% of patients suffering from cirrhosis. Today, PPH is comorbid in 4-6% of those referred for a liver transplant.

[0008] Despite there being treatments for PAH and PPH, the current prostacyclin therapies are associated with severe toxicity and tolerability issues, as well as the requirement for inconvenient dosing schedules. The present invention overcomes addresses these factors by providing compounds and that provide for less toxicity, better tolerability and more convenient dosing schedules, and methods for manufacturing the same.

SUMMARY OF THE INVENTION

[0009] Methods for the manufacture of treprostinil prodrugs and treprostinil derivative prodrugs are provided herein, e.g., compounds of the Formulae (I), (II) or (III). The treprostinil or treprostinil derivative prodrug, in one embodiment, comprises an ester or amide linkage to the prodrug moiety.

[0010] One aspect of the invention relates to the synthesis of a carboxylic acid derivative of treprostinil. In one embodiment, a treprostinil ester derivative of the formula

is esterified by mixing the appropriate alcohol (i.e., R2-OH where the R2 is a linear or branched C5-C18 alkyl, a linear C2-C18 alkenyl or a branched C3-C18

alkenyl) with treprostinil or a compound of the formula ^K 3 in the presence of an acid catalyst. The acid catalyst in one embodiment is a resin or in some other solid form. The acid catalyst in one embodiment is sulfuric acid or sulfonic acid. Other acid catalysts (in solid, e.g., a resin, or liquid form) include but are not limitied to hydrofluoric acid, phosphoric acid, toluenesulfonic acid, polystyrene solfonate, hyeteropoly acid, zeolites, metal oxides, and graphene oxygene diments, the treprostinil or treprostinil compound of the formula

³ (where R3, R4 and n are defined above) and/or alcohol R2-OH is dissolved in a solvent prior to the esterification reaction.

[0012] In another embodiment, the Mitsunobu reaction can be used, where a mixture of triphenylphosphine (PPI1 ₃ ) and diisoporpyl azodicarboxylate (DIAD or its diethyl analogue, DEAD) convert an alcohol and carboxylic acid to the ester to form one of the carboxylic acid ester prodrugs provided herein.

[0013] In yet another embodiment, N, N'-dicyclohexylcarbodiimide (DCC) or N, N'- diisopropylcarbodiimide (DIC) is used in combination with 4-dimethylaminopyridine (DMAP) in an esterification reaction (sometimes referred to as Steglich esterification).

[0014] Treprostinil amide derivatives (e.g., of the formula: ) can be manufactured according to well known protocols of amide functionalization of a carboxylic

acid group. For example, treprostinil (or a compound of the formula

(for example, dissolved in dioxane) is combined with HATU or PyBOP and alkylamine R ₂ -

NH ₂ R2, R3, R4 and n are defined herein.

[0015] The methods provided herein in one embodiment, are used to manufacture a prostacyclin compound of Formula (I), or a pharmaceutically acceptable salt: Formula (I)

wherein Ri is NH, O or S; R2 is H, a linear C5-C1 ₈ alkyl, branched C5-C1 ₈ alkyl, linear C2-C1 ₈ alkenyl, branched C3-C1 ₈ alkenyl, aryl; aryl-Ci-Cis alkyl; an amino acid or a peptide; R3 is H, OH, O-alkyl or O-alkenyl; R4 is an optionally substituted linear or branched C1-C15 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl; and n is an integer from 0 to 5, with the proviso that the prostacyclin compound is not treprostinil.

[0016] In another embodiment, a method provided herein is used to manufacture a prostacyclin compound of Formula (II), or a pharmaceutically acceptable salt:

Formula (II)

wherein Ri is NH, O or S; R2 is a linear or branched C5-C18 alkyl, a linear C2-C18 alkenyl or a branched C3-C1 ₈ alkenyl, aryl, aryl-Ci-Cis alkyl, an amino acid or a peptide; and n is an integer from 0 to 5.

[0017] In one embodiment, a compound of Formula (I) and/or (II) is manufactured by a method described herein, wherein one or more hydrogen atoms is substituted with a deuterium. Accordingly, in one embodiment, the present invention relates to an isotopologue of Formula (I) and/or (II), substituted with one or more deuterium atoms. The isotopologue of Formula (I) and/or (II) may be used to accurately determine the concentration of compounds of Formula (I) and/or (II) in biological fluids and to determine metabolic patterns of compounds of Formula (I) and/or (II) and its isotopologues.

[0018] Yet another embodiment of the invention relates to a method for manufacturing the prostacyclin compound of Formula (III), or a pharmaceutically acceptable salt,: Formula (III), wherein Ri and R2 are defined above, and

R ₅ and R6 are independently selected from H, optionally substituted linear or branched C1-C15 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)- optionally substituted linear or branched C1-C15 alkyl, or (C=0)-optionally substituted linear or branched C2-C15 alkenyl, with the proviso that the prostacyclin compound of Formula (III) is not treprostinil.

BRIEF DESCRIPTION OF THE FIGURES

[0019] Figure 1 is an esterification scheme for an alkyl ester-TR prodrug compound provided herein.

[0020] Figure 2 is a general scheme for synthesis of acylated treprostinil derivative prodrugs.

DETAILED DESCRIPTION OF THE INVENTION

[0021] The term "alkyl" as used herein refers to both a straight chain alkyl, wherein alkyl chain length is indicated by a range of numbers, and a branched alkyl, wherein a branching point in the chain exists, and the total number of carbons in the chain is indicated by a range of numbers. In exemplary embodiments, "alkyl" refers to an alkyl chain as defined above containing 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 carbons (i.e., Ce-Cie alkyl).

[0022] The term "alkenyl" as used herein refers to a carbon chain containing one or more carbon-carbon double bonds.

[0023] The term "aryl" as used herein refers to a cyclic hydrocarbon, where the ring is characterized by delocalized π electrons (aromaticity) shared among the ring members, and wherein the number of ring atoms is indicated by a range of numbers. In exemplary embodiments, "aryl" refers to a cyclic hydrocarbon as described above containing 6, 7, 8, 9, or 10 ring atoms (i.e., Ce-Cw aryl). Examples of an aryl group include, but are not limited to, benzene, naphthalene, tetralin, indene, and indane. [0024] The term "alkoxy" as used herein refers to -O-(alkyl), wherein "alkyl" is as defined above.

[0025] The term "substituted" in connection with a moiety as used herein refers to a further substituent which is attached to the moiety at any acceptable location on the moiety. Unless otherwise indicated, moieties can bond through a carbon, nitrogen, oxygen, sulfur, or any other acceptable atom.

[0026] The term "amino acid" refers to both natural (genetically encoded) and non-natural (non-genetically encoded) amino acids, and moieties thereof. Of the twenty natural amino

R

H ₂ N-C-C0 ₂ H

acids, 19 have the general structure: ^H , where R is the amino acid sidechain.

The 20 ^th amino acid, proline, is also within the scope of the present invention, and has the Of the twenty natural amino acids, all but glycine is chiral, and both the D- and L- amino acid isomers, as well as mixtures thereof, are amenable for use with the prostacyclin compounds described herein. It is also noted that an amino acid moiety is encompassed by the term "amino acid." For example, the amino acid moieties -CO- are encompassed by the term

"amino acid."

[0027] Examples of non-natural amino acids amenable for use with the present invention include β-alanine (β-Ala); 2,3-diaminopropionic acid (Dpr); nipecotic acid (Nip); pipecolic acid (Pip); ornithine (Om); citrulline (Cit); t-butylalanine (t-BuA); 2-tbutylglycine (t-BuG); N-methylisoleucine (Melle); phenylglycine (PhG); cyclohexylalanine (ChA); norleucine (Nle); naphthylalanine (Nal); 4-chlorophenylalanine (Phe(4-Cl)); 2-fluorophenylalanine (Phe(2-F)); 3-fluorophen ylalanine (Phe(3-F)); 4-fluorophenylalanine (Phe( 4-F)); penicillamine (Pen); l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic); β-2- thienylalanine (Thi); methionine sulfoxide (MSO); homoarginine (hArg); N-acetyllysine (AcLys); 2,4-diaminobutyric acid (Dbu); 2,3-diaminobutyric acid (Dab); p- aminophenylalanine (Phe (pNH^)); N-methyl valine (MeVal); homocysteine (hCys), homophenylalanine (hPhe); homoserine (hSer); hydroxyproline (Hyp); homoproline (hPro); and the corresponding D-enantiomer of each of the foregoing. Other non-genetically encoded amino acid residues include 3-aminopropionic acid; 4-aminobutyric acid; isonipecotic acid (Inp); aza-pipecolic acid (azPip); aza-proline (azPro); a-aminoisobutyric acid (Aib); ε- aminohexanoic acid (Aha); δ-aminovaleric acid (Ava); N-methylglycine (MeGly).

[0028] A "peptide" is a polymer of amino acids (or moieties thereof) linked by a peptide bond. Peptides for use with the present invention, comprise from about two to about fifteen amino acids, for example, two, three, four, five, six, seven, eight, nine or ten amino acids (or moieties thereof).

[0029] The term "salt" or "salts" as used herein encompasses pharmaceutically acceptable salts commonly used to form alkali metal salts of free acids and to form addition salts of free bases. The nature of the salt is not critical, provided that it is pharmaceutically acceptable. Suitable pharmaceutically acceptable acid addition salts may be prepared from an inorganic acid or from an organic acid. Exemplary pharmaceutical salts are disclosed in Stahl, P.H., Wermuth, C.G., Eds. Handbook of Pharmaceutical Salts: Properties, Selection and Use; Verlag Helvetica Chimica Acta/Wiley-VCH: Zurich, 2002, the contents of which are hereby incorporated by reference in their entirety. Specific non-limiting examples of inorganic acids are hydrochloric, hydrobromic, hydroiodic, nitric, carbonic, sulfuric and phosphoric acid. Appropriate organic acids include, without limitation, aliphatic, cycloaliphatic, aromatic, arylaliphatic, and heterocyclyl containing carboxylic acids and sulfonic acids, for example formic, acetic, propionic, succinic, glycolic, gluconic, lactic, malic, tartaric, citric, ascorbic, glucuronic, maleic, fumaric, pyruvic, aspartic, glutamic, benzoic, anthranilic, mesylic, stearic, salicylic, -hydroxybenzoic, phenylacetic, mandelic, embonic (pamoic), methanesulfonic, ethanesulfonic, benzenesulfonic, pantothenic, toluenesulfonic, 2-hydroxyethanesulfonic, sulfanilic, cyclohexylaminosulfonic, algenic, 3-hydroxybutyric, galactaric or galacturonic acid. Suitable pharmaceutically acceptable salts of free acid-containing compounds disclosed herein include, without limitation, metallic salts and organic salts. Exemplary metallic salts include, but are not limited to, appropriate alkali metal (group la) salts, alkaline earth metal (group Ila) salts, and other physiological acceptable metals. Such salts can be made from aluminum, calcium, lithium, magnesium, potassium, sodium and zinc. Exemplary organic salts can be made from primary amines, secondary amines, tertiary amines and quaternary ammonium salts, for example, tromethamine, diethylamine, tetra-N-methylammonium, N,N- dibenzylethylenediamine, chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine (N-methylglucamine) and procaine. [0030] Methods are provided herein for the synthesis of treprostinil prodrugs, as well as treprostinil derivative prodrugs, for example prodrugs of Formulae (I), (II) and (III). The prodrugs find utility in the treatment of pulmonary hypertension, for example, pulmonary arterial hypertension and portopulmonary hypertension, as well as other indicaitons, as described in U.S. Patent Application Publication No. 2015/0148414, published May 28, 2015, the disclosure of which is incorporated by reference in its entirety for all purposes., For example, the treprostinil derivative prodrug or treprostinil prodrug, or a composition comprising the same, is effective when employed in a once-daily, twice-daily or three-times daily dosing regimen, for example, for the treatment of pulmonary arterial hypertension or portopulmonary hypertension in a patient in need thereof. The prostacyclin compound provided herein, in one embodiment, can be administered less frequently than treprostinil, with equal or greater efficacy. Moreover, in one embodiment, the side effect profile of the compounds provided herein is less deleterious than the side effect profile resulting from treprostinil administration.

[0031] One aspect of the invention relates to the synthesis of a carboxylic acid derivative of treprostinil. In one embodiment, a treprostinil ester derivative of the formula

the R2 is a linear or branched C5-C1 ₈ alkyl, a linear C2-C1 ₈ alkenyl or a branched C3-C1 ₈

alkenyl) with treprostinil or a compound of the formula in the presence of an acid catalyst. As provided herein, R ₃ is H, OH, optionally substituted linear or branched C1-C 5 alkyoxy, O-optionally substituted linear or branched C2-C15 alkenyl, O- (C=0)-optionally substituted linear or branched C1-C15 alkyl, or 0-(C=0)-optionally substituted linear or branched C2-C15 alkenyl; R4 is an optionally substituted linear or branched C1-C 5 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl; and n is an integer from 0 to 5. It will be appreciated by one of ordinary skill in the art that the purity of the final product will depend in part on the purity of the reagents employed in the esterification reaction, and/or the cleanup procedure after the reaction has completed. For example, a high purity alcohol will give a higher purity treprostinil ester derivative than a lower purity alcohol. Similarly, a higher purity product is obtained through clean-up procedures such as HPLC, diafiltration, etc.

[0032] The acid catalyst in one embodiment is a resin or in some other solid form. However, in other embodiment, the acid catalyst is in liquid form. The acid catalyst in one embodiment is sulfuric acid or sulfonic acid. Other acid catalysts (in solid, e.g., a resin, or liquid form) include but are not limited to hydrofluoric acid, phosphoric acid, toluenesulfonic acid, polystyrene solfonate, hyeteropoly acid, zeolites, metal oxides, and graphene oxygene.

[0033] Acid catalyst resins, e.g., sulfonic acid resin catalysts are available commercially, e.g., from Sigma-Aldrich, under the trade name AMBERLYST. Other resins are available commercially, e.g., from Purolite®, and are amenable for use with the methods described herein.

[0034] In some embodiments, the treprostinil or the treprostinil compound of the formula

n are defined above) and/or alcohol R2-OH is dissolved in a solvent prior to the esterification reaction. For example, in one embodiment, where treprostinil is esterified with an alkyl group having 12 carbon atoms or more, treprostinil is first dissolved in a solvent such as dioxane prior to the esterification reaction. Other solvents besides dioxane, or in combination with dioxane can also be used. For example, acetonitrile (MeCN), Ν,Ν'-dimethylformamide (DMF), dichloromethane (DCM), or a combination thereof can be used. Various examples of solvents are provided in Table 1 below.

Table 1

Solvents amenable for use in

esterification reactions.

Dioxane Dioxane (2 niL/100 μηιοΐ TRP)

Dioxane (1 niL/100 μηιοΐ TRP)

DMF

DCM

MeCN

1 : 1 Dioxane:MeCN

DMF/DCM

10% DMF/DCM

20% DMF/DCM

[0035] Carboxylic acid esterification reactions other than the ones described above are known to those of ordinary skill in the art and are amenable for use in manufacturing the treprostinil alkyl esters described herein. For example, the Mitsunobu reaction can be used, where a mixture of triphenylphosphine (PPI1 ₃ ) and diisoporpyl azodicarboxylate (DIAD or its diethyl analogue, DEAD) convert an alcohol and carboxylic acid to the ester. In this reaction, the DIAD is reduced as it serves as the hydrogen acceptor, and the PPh ₃ is oxidized to OPPh ₃ .

[0036] In yet another embodiment, N, N'-dicyclohexylcarbodiimide (DCC) or N, N'- diisopropylcarbodiimide (DIC) is used in combination with 4-dimethylaminopyridine (DMAP) (additive) in an esterification reaction (sometimes referred to as Steglich esterification). In this reaction, DCC or DIC and the carboxylic acid (treprostinil or its non- esterified derivative) are able to form an O-acylisourea activated carboxylic acid intermediate. The alcohol is added to the activated compound to form the stable dicyclohexylurea and the ester. In one embodiment, the treprostinil or its non-esterified derivative is first dissolved in solvent, e.g., one of the solvents described above, prior to performing the Steglich esterification.

[0037] Other esterification reactions can be employed. For example, l-[Bis (dimethylamino) methylene]- lH-l,2,3-triazolo[4,5-b] pyridinium 3-oxid hexafluorophosphate (HATU) or benzotriazol-l-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP) can be used as a coupling reagent. These reagents can be used with or without an additive to facilitate the coupling. For example, triethylamine (TEA) can be used in some embodiments in conjunction with either HATU or PyBOP coupling reagents to form a treprostinil alkyl ester. As with the other esterification reactions described herein, the treprostinil or non-esterified treprostinil derivative can first be dissolved in solvent prior to performing the esterification reaction. [0038] In yet another embodiment, an esterification of treprostinil or a treprostinil derivative proceeds through steps 1 through 5 of the reaction scheme set forth in Example 3 of PCT Publication No. WO 201 1/153363, incorporated by reference herein in its entirety for all purposes.

[0039] Treprostinil amide derivatives (e.g., of the formula: ) can be manufactured according to protocols of amide functionalization of a carboxylic acid group.

For example, treprostinil (or a compound of the formula (for example, dissolved in dioxane) is combined with HATU or PyBOP and alkylamine R2-NH2 R2, R3, R4 and n are defined above.

[0040] Other reaction conditions for forming treprostinil amide derivatives with alkylamine R2-NH2, are provided below in Table 2.

Table 2

Coupling Amine

Entry Solvent Time Reagent Additive Base (Equiv) Amine Delav

12 DMF 48 h DSC - DIPEA 5.0 24 h

13 Dioxane 48 h DCC DMAP — 10.0 —

14 Dioxane 48 h DCC — — 10.0 -

115

15 Dioxane h DSC DIPEA 5.0 91 h

16 Dioxane 18 h DSC DMAP DIPEA 5.0 150 m

115

17 Dioxane h DSC DMAP DIPEA 5.0 91 h

18 Dioxane 86 h DSC — DIPEA 7.5 68 h

19 DMF 1 h HATU — DIPEA 1.2 —

20 DMF 1 h PyBOP - DIPEA 1.2 —

1 :2

21 Dioxane:MeCN lh PyBOP DIPEA 1.2

22 Dioxane 18 h DCC HOBt DIPEA 1.2 -

23 Dioxane 18 h DIC HOBt DIPEA 1.2 —

24 Dioxane 18 h EDC HOBt DIPEA 1.2 —

25 Dioxane 48 h DCC NHS DIPEA 1.2 24 h

26 Dioxane 48 h DIC NHS DIPEA 1.2 24 h

27 Dioxane 48 h EDC NHS DIPEA 1.2 24 h

28 Dioxane 48 h DCC PfpOH DIPEA 1.2 24 h

29 Dioxane 48 h DIC PfpOH DIPEA 1.2 24 h

30 Dioxane 48 h EDC PfpOH DIPEA 1.2 24 h

DCC = N,N'-Dicyclohexylcarbodiimide

DIC = N,N'-Diisopropylcarbodiimide

DSC = Ν,Ν'-Disuccinimidyl carbonate

DIPEA = N,N-Diisopropylethylamine

DMF = N,N'-dimethylformamide

EDC = N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride

HATU = l-[Bis(dimethylamino)methylene]-lH-l,2,3-triazolo[4,5-b]pyri dinium 3-oxid hexafluorophosphate

HOBt = 1-Hydroxybenzotriazole hydrate

MIBA = 5-methoxy-2-iodophenylboronie acid

PyBOP = benzotriazol- 1-yl-oxytripyrrolidinophosphonium hexafluorophosphate

PfpOH = 2,2,3,3,3-Pentafluoro-l-propanol [0041] In one aspect of the invention described herein, a prostacyclin compound of Formula (I), or a pharmaceutically acceptable salt thereof, is manufactured by a method described herein:

Formula (I),

wherein Ri is NH, O or S;

R2 is H, a linear C5-C1 ₈ alkyl, branched C5-C1 ₈ alkyl, linear C2-C1 ₈ alkenyl, branched C3-C1 ₈ alkenyl, aryl, aryl-Ci-Cis alkyl; an amino acid or a peptide;

R ₃ is H, OH, optionally substituted linear or branched C1-C15 alkyoxy, O-optionally substituted linear or branched C2-C15 alkenyl, 0-(C=0)-optionally substituted linear or branched C1-C15 alkyl, or 0-(C=0)-optionally substituted linear or branched C2-C15 alkenyl;

R4 is an optionally substituted linear or branched C1-C15 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl; and

n is an integer from 0 to 5, with the proviso that the prostacyclin compound of Formula (I) is not treprostinil.

[0042] In a further embodiment, a prostacyclin compound of Formula (I) is manufactured, wherein R ₃ is OH and n is 0 or 1. In even a further embodiment, R4 is an optionally substituted linear or branched C1-C 5 alkyl. In even a further embodiment, Ri is NH or O.

[0043] In one embodiment, a prostacyclin compound of Formula (I) is manufactured, wherein Ri is NH, O or S; R2 is a linear C5-C1 ₈ alkyl, branched C5-C1 ₈ alkyl, linear C2-C1 ₈ alkenyl, branched C3-C18 alkenyl; R3 is H, OH or O-alkyl; R4 is an optionally substituted linear or branched C1-C15 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl; and n is an integer from 0 to 5. In even a further embodiment, Ri is NH or O and R2 is a linear C5-C1 ₈ alkyl or a branched C5-C1 ₈ alkyl.

[0044] In one embodiment, R2 is aryl or aryl-Ci-Cis alkyl; R ₃ is OH and n is 0 or 1. In even a further embodiment, R4 is an optionally substituted linear or branched C1-C15 alkyl. [0045] In one embodiment, the present invention provides a method for manufacturing prostacyclin compound of Formula (I), wherein the compound is a compound of one Formulae (la), (lb), (Ic) or (Id), or a pharmaceutically acceptable salt thereof:

Formula (la) Formula (lb) Formula (Ic) Formula (Id) wherein, R2 is H, a linear or branched C5-C1 ₈ alkyl, linear C2-C1 ₈ alkenyl, or a branched C3-C1 ₈ alkenyl;

R3 is H, OH, optionally substituted linear or branched C1-C15 alkyoxy, O-optionally substituted linear or branched C2-C15 alkenyl, -0(C=0)-optionally substituted linear or branched C1-C15 alkyl, or -0(C=0)-optionally substituted linear or branched C2-C15 alkenyl; and

R4 is , an optionally substituted linear or branched C1-C 5 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl, where R5 is H, optionally substituted linear or branched C1-C 5 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)-optionally substituted linear or branched C1-C15 alkyl, or (C=0)-optionally r branched C2-C15 alkenyl. In a further embodiment, R4 is , with the proviso that the compound is not treprostinil, i.e., R2 and R5 cannot both be H.

[0046] In one embodiment of Formula (la), Formula (lb), Formula (Ic) and Formula (Id), R2

is a linear or branched C5-C1 ₈ alkyl. In even a further embodiment, R2 _is m1 ' m2 _or

\

CR'R'

R ,' A ^R , , where ml and m2 are each independently an integer selected from 1 to 9 and each occurrence of R' is independently H, a linear or branch C -C alkyl, or a linear or branched

Ci-C alkenyl. In even a further embodiment, R2 is ^{m1 m2} and ml and m2 are both 4.

In another embodiment, R2 is ^{m1 m2} and ml is 3 and m2 is 4, or ml is 2 and m2 is 3.

[0047] When ml and/or m2 is an integer from 2-9, the ml/m2 at the end of the carbon chain is CH ₃ , while the remaining ml/m2 groups are CI¾.

[0048] In one embodiment of Formula (la), Formula (lb), Formula (Ic) and Formula (Id), R2

linear or branched C1-C 5 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)-optionally substituted linear or branched C1-C15 alkyl, or (C=0)-optionally substituted linear or branched C2-C15 alkenyl.

[0049] In one embodiment of Formulae (la), (lb), (Ic) or (Id), R2 is H, R ₃ is OH and R4 is

, where ml and m2 are each independently an integer selected from 1 to 9 and each occurrence of R' is independently H, a linear or branched Ci-Cs alkyl, or a linear or branched Ci-Cs alkenyl. When ml and/or m2 is an integer from 2-9, the ml/m2 at the end of the carbon chain is CH ₃ , while the remaining ml/m2 groups are CH ₂ .

[0050] In another embodiment, a method for manufacturing a prostacyclin compound of one of Formula (la), (lb), (Ic) or (Id) is provided wherein R ₃ is OH, as provided in one of Formulae (la'), (lb'), (Ic') or (Id'):

Formula (la') Formula (lb') Formula (Ic') Formula (Id') wherein, branched C5-C1 ₈ alkyl, or a linear or branched C5-C1 ₈ alkenyl;

and R4 is , an optionally substituted linear or branched C1-C15 alkyl, or an optionally substituted linear or branched C2-C15 alkenyl, wherein R5 is H, optionally substituted linear or branched C1-C 5 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)-optionally substituted linear or branched C1-C 5 alkyl, or (C=0)-optionally substituted linear or branched C2-C15 alkenyl, with the proviso that R2 and R5 are not both H.

occurrence of R' is independently H, a linear or branched -Cs alkyl, or a linear or branched

Ci-Cs alkenyl. In even a further embodiment, R2 is

[0051] Yet another embodiment of the invention relates to a method for manufacturing a prostacyclin compound of one of Formula (la"), (lb"), (Ic") or (Id"), or a pharmaceutically acceptable salt thereof:

Formula (la") Formula (lb")

Formula (Ic") Formula (Id") wherein,

R2 is H, a linear or branched C5-C1 ₈ alkyl, linear C2-C1 ₈ alkenyl, branched C3-C1 ₈ alkenyl, aryl, aryl-Ci-Cis alkyl; an amino acid or a peptide; and

R3 is H, OH, optionally substituted linear or branched C1-C15 alkyoxy, O-optionally substituted linear or branched C2-C15 alkenyl, 0-(C=0)-optionally substituted linear or branched C1-C15 alkyl, or 0-(C=0)-optionally substituted linear or branched C2-C15 alkenyl; and

R5 is H, optionally substituted linear or branched C1-C 5 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)-optionally substituted linear or branched C1-C 5 alkyl, or (C=0)-optionally substituted linear or branched C2-C15 alkenyl, with the proviso that R2 and R5 are not both H. In a further embodiment, R ₃ is OH and R2 is 5-nonanyl, 4-heptyl, 4-octyl, 3-octyl, 2-dimethyl-l -propyl, 3,3-dimethyl-l-butyl, 2-ethyl-l -butyl, 3-pentyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl. In even a further embodiment, R ₂ is decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl. In even a further embodiment, R2 is a linear alkyl.

[0052] One embodiment of the present invention is directed to a method for manufacturing a compound of Formula (Ic), (Ic') and (Ic"). In a further embodiment, R ₂ is a linear C5-C1 ₈ alkyl or a branched C5-C1 ₈ alkyl. In even a further embodiment, R2 is a linear C6-C1 ₈ alkyl or a branched C6-C1 ₈ alkyl. In yet a further embodiment, R2 is a linear C6-C14 alkyl, e.g., a linear Ce alkyl, Cs alkyl, C ₁₀ alkyl, C ₁₂ alkyl or C ₁₄ alkyl.

[0053] In one embodiment, a compound of Formula (Ic") is provided wherein R2 is a linear C5-C1 ₈ alkyl; R ₃ is OH and R5 is H. In another embodiment, a compound of Formula (Ic") is provided wherein R ₂ is a linear C6-C1 ₈ alkyl; R ₃ is OH and R5 is H. In yet embodiment, a compound of Formula (Ic") is provided wherein R ₂ is a linear C6-C1 ₆ alkyl; R ₃ is OH and R5 is H. In even another embodiment, a compound of Formula (Ic") is provided wherein R2 is a linear Cs-Ci4 alkyl; R ₃ is OH and R5 is OH.

[0054] In one embodiment, a method for manufacturing a prostacyclin compound of Formula (Ic") is provided wherein R2 is a linear C5-C1 ₈ alkyl; R ₃ is OH and R5 is H. In another embodiment, a compound of Formula (Ic") is provided wherein R2 is a branched C6-C18 alkyl; R ₃ is OH and R5 is H. In yet embodiment, a compound of Formula (Ic") is provided wherein R2 is a branched C6-C1 ₆ alkyl; R ₃ is OH and R5 is H. In even another embodiment, a compound of Formula (Ic") is provided wherein R ₂ is a branched Cs-Ci4 alkyl; R ₃ is OH and R ₅ is H.

[0055] In yet another embodiment a method for manufacturing a prostacyclin compound of Formula (la"), (lb"), (Ic") or (Id") is provided, wherein R ₃ is OH, R ₅ is H and R ₂ is and ml and m2 are each independently an integer selected from

1 to 9. In even a further embod

rmula (la"), (lb"), (Ic") or (Id"), R ₂ is H, R ₃ is OH,

where ml and m2 are each independently an integer selected from 1 to 9. In even a further embodiment, I¾ is

[0057] In one embodiment, a method for manufacturing a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is provided where R2 is a linear or branched C5-C1 ₈ alkyl. In a further embodiment, R2 is 5-nonanyl, 4-heptanyl, 4-octanyl, 3-octanyl, 2-dimethyl-l- propanyl, 3,3-dimethyl-l-butanyl, 2-ethyl-l-butanyl, 3-pentanyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl.

[0058] In one embodiment, a method for manufacturing a prostacyclin compound of Formula (I), (la), (lb), (Ic), (Id), (la'), (lb'), (Ic'), (Id'), (la"), (lb"), (Ic") or (Id") is provided where R2 is a linear or branched C5-C18 alkyl. In even a further embodiment, R2 is a linear C5-C18

alkyl. In another embodiment, R2 is , where ml and m2 are each independently an integer selected from 1 to 9 and each occurrence of R' is independently H, a linear or branched Ci-Cs alkyl, or a linear or branched Ci-Cs alkenyl. In even a further

[0059] In another embodiment, a method for manufacturing a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is provided wherein R ₂ is a branched C5-C1 ₈ alkyl. In a further embodiment, R ₂ is 5-nonanyl, 4-heptyl, 4-octyl, 3-octyl, 2-dimethyl-l -propyl, 3,3- dimethyl-1 -butyl, 2-ethyl-l -butyl, 3 -pentyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl.

[0060] In one embodiment of the invention, the prostacyclin compound manufactured by the methods provided herein has the following structure:

wherein Ri is NH, O or S.

[0061] For example, Ri is O or N, and one of the following compounds (5-nonanyl treprostinil (alkyl ester, 5C ₉ -TR) or 5-nonanyl treprostinil (amide linked; 5C9-TR-A), is provided:

[0062] In one embodiment, a method for manufacturing a prostacyclin compound of Formula

(I), (la), (lb), (Ic) or (Id) is provided wherein R ₂ is , where ml and m2 are each independently each an integer selected from 1 to 9 and each occurrence of R' is independently H, a linear or branched Ci-Cs alkyl, or a linear or branched Ci-Cs alkenyl.

[0063] When ml and/or m2 is an integer from 2-9, the ml/m2 at the end of the carbon chain is CH ₃ , while the remaining ml/m2 groups are CH ₂ .

[0064] In even another embodiment, a method for manufacturing a prostacyclin compound of

'), (lb'), (Ic'), (Id'), (la"), (lb"), (Ic") or (Id") is

[0065] The compounds provided herein can include a symmetrical branched alkyl or an asymmetrical branched alkyl as the R2 moiety.

and m2 can be the same integer and R2 is therefore a symmetrical branched alkyl. R2 is an assymetrical branched alkyl when ml and m2 are different.

[0066] In another embodiment, a compound of Formula (I), (la), (lb), (Ic), (Id), (la'), (lb'),

(Ic'), (Id'), (la"), (lb"), (Ic") or (Id") is provided, , ml is 2 and m2 is 3, ml and m2 are each independently 4, or ml and m2 are each independently 3 is provided via one of the methods described herein.

[0067] In another embodiment, the prostacyclin compound manufactured by the disclosed methods comprises an asymmetrical branched alkyl at the R2 position, such as, for example, 3-hexanyl (3Ce), 2-heptanyl (2C ₇ ), 3-heptanyl (3C ₇ ), 2-octanyl (2C ₈ ), 3-octanyl (3C ₈ ), or 4- octanyl (4C ₈ ).

[0068] In another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is manufactured by the disclosed methods, wherein R ₂ is a branched alkyl selected from 2,2- diethyl-l-pentyl, 3-pentyl, 4-octyl, 5-nonanyl, 2-ethyl-l -butyl, 2-propyl-l-pentyl, 12-butyl-l- octyl, 2-dimethyl-l -propyl, and 3,3-dimethyl-l-butyl.

[0069] In yet another embodiment, a method for manufacturing a prostacyclin compound of Formula (I), (la), (lb), (Ic), (Id), (la'), (lb'), (Ic') or (Id') is provided, wherein, R ₂ is a linear or branched C5-C18 alkenyl. For example, in one embodiment, R2 is a linear C5-C1 ₈ alkenyl selected from pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl or octadecenyl. In a further embodiment, R3 is OH. In another embodiment, R2 is a branched C5-C1 ₈ alkenyl selected from pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl or octadecenyl. In a further embodiment, R ₃ is OH. [0070] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is provided and R4 is is synthesized by one of the methods provided

herein. In a further embodiment, R4 is ^OH

[0071] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is is synthesized by one of the methods provided herein and R2 a linear C5-C18 alkyl, R ₃ is OH and In a further embodiment, R2 is 5-nonanyl, 4-heptyl, 4- octanyl, 3-octanyl, 2-dimethyl-l -propyl, 3,3-dimethyl-l-butyl, 2-ethyl-l -butyl, 3-pentyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl.

[0072] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is is synthesized by one of the methods provided herein and R2 hexyl, dodecyl, tetradecyl, hexadecyl, 5-nonanyl, 4-heptanyl, 4-octanyl, 3-o l, 3,3-dimethyl-l- butyl, 2-ethyl-l -butyl, 3-pentyl, R ₃ is OH and R4

[0073] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is is synthesized by one of the methods provided herein and R2 hexyl, R ₃ is OH and R4 is

[0074] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id) is is synthesized by one of the methods described herein and R2 hexyl, R3 is OH and R4 is

[0075] In another embodiment, a method for manufacturing a prostacyclin compound of Formula (la"), (lb"), (Ic") or (Id") is provided and R ₂ hexyl, R ₃ is OH R4 is H. In a further embodiment, the prostacyclin compound is a compound of Formula (Ic"). In yet another embodiment, a prostacyclin compound of Formula (la"), (lb"), (Ic") or (Id") is provided and R2 dodecyl, tetradecyl, pentadecyl or hexadecyl, R ₃ is OH R4 is H. In a further embodiment, the compound is a compound of Formula (la"). In even a further embodiment, the compound is present in a lipid nanoparticle formulation as described in more detail below.

[0076] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is synthesized by a method described herien, and R2 heptyl,

[0077] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and R2 octyl, R ₃ is OH and R4

[0078] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and R2 nonyl, R3 is OH and R4 is

[0079] In another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and

R2 decyl, R ₃ is OH and R4 is

[0080] In yet another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and

R2 undecyl, R ₃ is OH and R4

[0081] In even another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and R2 dodecyl, R ₃ is OH and R4

[0082] In one embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herien, and R2 tridecyl, R ₃ is OH and R4 is [0083] In another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic), or (Id), or pharmaceuticall ed by a method described herein, and

R ₂ tetradecyl, R ₃ is OH

[0084] In even another embodiment, a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt, is is synthesized by a method described herein, and R2 pentadecyl, R3 is OH and R4 is

[0085] Another embodiment of the invention concerns a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or pharmaceutically acceptable salt is synthesized by a method described herien, wherein R ₂ hexadecyl, R ₃ is OH and R4 is

[0086] Yet another embodiment of the invention concerns a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), a or pharmaceutically acceptable salt is synthesized by a method described herein, wherein R ₂ heptadecyl, R ₃ is OH and R4 is

[0087] Yet another embodiment of the invention concerns a prostacyclin compound of Formula (I), (la), (lb), (Ic) or (Id), or a pharmaceutically acceptable salt is synthesized by a method described herien, wherein R ₂ octadecyl, R ₃ is OH and R4 is

[0088] In one embodiment, a method is provided for manufacturing a compound of Formula (I), (la), (lb), (Ic) or (Id), or a pharmaceutically acceptable salt, wherein one or more hydrogen atoms is substituted with a deuterium. Accordingly, in one embodiment, the present invention relates to an isotopologue of Formula (I), (la), (lb), (Ic) or (Id), substituted with one or more deuterium atoms. The isotopologue of Formula (I), (la), (lb), (Ic) or (Id) may be used to accurately determine the concentration of compounds of Formula (I), (la), (lb), (Ic) or (Id) in biological fluids and to determine metabolic patterns of compounds of Formula (I), (la), (lb), (Ic) or (Id) and its isotopologues.

[0089] In another embodiment of the invention, a method for manufacturing a prostacyclin compound of Formula (II), or a pharmaceutically acceptable salt thereof, is provided: Formula (II),

wherein Ri is NH, O or S;

R2 is a linear or branched C5-C1 ₈ alkyl, a linear C2-C1 ₈ alkenyl or a branched C3-C1 ₈ alkenyl, aryl, aryl-Ci-Cis alkyl, an amino acid or a peptide; and

n is an integer from 0 to 5.

[0090] In one embodiment, the method comprises manufacturing a prostacyclin compound of Formula (II), or a pharmaceutically acceptable salt thereof, wherein Ri is NH, O or S; R2 is a linear or branched C5-C1 ₈ alkyl, a linear C2-C1 ₈ alkenyl or a branched C3-C1 ₈ alkenyl; and n is an integer from 0 to 5. In a further embodiment, n is 1 and Ri is NH or O.

[0091] In one embodiment, the method comprises manufacturing a prostacyclin compound of Formula (II), wherein the prostacyclin compound is a compound of formula (Ila), (lib), (lie) or (lid), or a pharmaceutically acceptable salt thereof:

Formula (lie) Formula (lid) wherein R2 is a linear or branched C5-C1 ₈ alkyl, a linear C2-C1 ₈ alkenyl or a branched C3-C1 ₈ alkenyl, aryl, aryl-Ci-Cis alkyl, an amino acid or a peptide. In a further embodiment, a compound of formula (Ila), (lib), (lie) or (lid) is provided wherein R ₂ is a linear or branched C5-C1 ₈ alkyl, a linear C2-C1 ₈ alkenyl or a branched C3-C1 ₈ alkenyl. In one embodiment, a compound of Formula (II), (Ila), (lib), (lie) or (lid) is provided, wherein one or more hydrogen atoms is substituted with a deuterium. Accordingly, in one embodiment, the present invention relates to an isotopologue of Formula (II), (Ila), (lib), (lie) or (lid), substituted with one or more deuterium atoms. The isotopologue of Formula (II), (Ila), (lib), (lie) or (lid) may be used to accurately determine the concentration of compounds of Formula (II), (Ila), (lib), (lie) or (lid) in biological fluids and to determine metabolic patterns of compounds of Formula (II), (Ila), (lib), (lie) or (lid) and its isotopologues. The invention further provides compositions comprising these deuterated isotopologues and methods of treating diseases and conditions, as set forth herein.

[0092] In another embodiment, the method comprises manufacturing a prostacyclin compound of Formula (lie). In a further embodiment, R2 is a linear C5-C1 ₈ alkyl or a branched C5-C1 ₈ alkyl. For example, in one embodiment, R2 is a linear C6-C1 ₈ alkyl. In another embodiment of Formula (lie), R2 is a linear C6-C1 ₀ alkyl. In even a further embodiment of Formula (lie), R2 is a hexyl, heptyl or octyl.

[0093] Compounds of Formula (Ila) and Formula (lid) that can be manufactured by the methods described herein are provided in tables 3 and 4 below.

Table 4. Compounds of Formula (He)

R2 = linear C ₅ -Cis alk l R ₂ = branched C ₅ -Ci ₈ alkyl R2 = linear C6 alkyl R ₂ = branched C6 alkyl

R2 = linear C6-C18 alkyl R ₂ = branched C6-Cis alkyl R2 = linear C7 alkyl R2 = branched C7 alkyl

R2 = linear C ₇ -Cis alkyl R ₂ = branched C ₇ -Ci ₈ alkyl R2 = linear C§ alkyl R ₂ = branched C§ alkyl

R2 = linear Cj-Cis alkyl R ₂ = branched C ₈ -Ci ₈ alkyl R2 = linear Cg alkyl R ₂ = branched Cg alkyl

R2 = linear Cg-Cis alkyl R ₂ = branched Cg-Cis alkyl R2 = linear C10 alkyl R ₂ = branched Qo alkyl

R2 = linear Cio-Cis alkyl R ₂ = branched Cio-Cis alkyl R2 = linear Cn alkyl R ₂ = branched Cn alkyl

R2 = linear C5-C12 alkyl R ₂ = branched C5-C12 alkyl R2 = linear C12 alkyl R ₂ = branched C12 alkyl

R2 = linear C6-C10 alkyl R ₂ = branched C ₆ -Ci ₀ alkyl R2 = linear C13 alkyl R ₂ = branched C13 alkyl

[0094] Yet another embodiment of the invention relates to a method for manufacturing a prostacyclin compound of Formula (III), or a pharmaceutically acceptable salt thereof:

(Formula III), wherein Ri and R2 are defined as provided for Formula (I) and (II), and

R5 and Re are independently selected from H, optionally substituted linear or branched C1-C15 alkyl, optionally substituted linear or branched C2-C15 alkenyl, (C=0)- optionally substituted linear or branched C1-C15 alkyl, or (C=0)-optionally substituted linear or branched C2-C15 alkenyl, with the proviso that the prostacyclin compound of Formula (III) is not treprostinil.

[0095] In one embodiment, the manufacturing methods provide prostacyclin compounds that contain a chiral moiety at one or more of the R ₂ , R5 and/or Re positions. For example, the moiety at position R ₂ , in one embodiment, is a chiral moiety and comprises either the R isomer, the S isomer, or a mixture thereof. An optical isomer at position R ₂ , R5 and/or Re can also be classified with the D/L nomenclature. For example, where R2 is an amino acid or an amino acid moiety, the amino acid or amino acid moiety can be the D-isomer, L-isomer, or a mixture thereof.

[0096] In one embodiment, one or more of the R2, 5 and/or I¾ moieties is the R isomer or S isomer. In another embodiment, one or more of the R2, R5 and/or R^ moieties provided herein comprise a mixture of R and S moieties. The "R isomer" or "S isomer" as used herein refers to an enantiomerically pure isomer. An "enantiomerically pure isomer" has at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% pure R- or S- isomer or when using the D/L nomenclature, D- or L-isomer. A racemic compound is a compound having a mixture in equal amounts of both enantiomers.

EXAMPLES

[0097] The present invention is further illustrated by reference to the following Examples. However, it should be noted that these Examples, like the embodiments described above, are illustrative and are not to be construed as restricting the scope of the invention in any way.

Example 1 - Synthesis of treprostinil alkyl esters

[0098] Treprostinil compounds derivatized with alkyl groups at the carboxylic acid moiety were prepared. Specifically, treprostinil was derivatized at the carboxylic acid moiety with C ₂ , C3, C ₄ , C5, Ce, Cs, Cio, C12, Ci6, and C ₁₈ alkyl chains (i.e., R2 in Formula (A), below, is C ₂ , C3, C ₄ , C5, Ce, Cs, Cio, C12, Ci ₆ or C ₁₈ alkyl) to make treprostinil alkyl esters of various ester chain lengths. Treprostinil can be synthesized, for example, by the methods disclosed in U.S. Patent Nos. 6,765, 117 and 8,497,393. Synthesis of prostaglandin derivatives is described in U.S. Patent No. 4,668,814. The disclosures of U.S. Patent Nos. 6,765,1 17; 8,497,393 and 4,668,814 are each incorporated by reference in their entireties for all purposes.

Formula (A)

[0099] Scheme 1 : [00100] Treprostinil esterification was catalyzed by strongly acidic resin Amberlyst®

15 (Rohm and Haas). Treprostinil acid was dissolved in anhydrous dioxane/alcohol at a concentration 10 mg/mL (typically 4 mL). Alcohol (R2-OH) added was appropriate to make corresponding chain length at the R2 group. By way of example, for the C2 (ethyl ester) compound, the alcohol was ethanol. The molar amount of alcohol in the solvent was ten times the molar amount of treprostinil.

[00101] Treprostinil in dioxane/alcohol solution was added to washed and dry

Amberlyst resin. Per each 40 mg treprostinil, 1 g resin in a glass vial was added. The mixture was placed on a shaker and incubated overnight at 40 °C. Next, the liquid portion was taken out of the vial, washed twice with 3 mL dioxane. All recovered solvent was then collected. The solvent was dried by nitrogen stream until the evaporation stopped. The remaining treprostinil alkyl ester and nonvolatile alcohol (if long chain alcohol used) was dissolved in 2 mL hexane/ethyl acetate 1 : 1, and cleaned by liquid-liquid extraction vs. equal volume of phosphate buffer, and then water. Next, the organic layer was separated and dried by nitrogen stream and further in vacuum. If a long chain alcohol used, an additional purification step was required to separate alcohol by liquid chromatography. ACE CN, 5 μιη, Ultra-Inert HPLC Column, 100x21.2 mm was used, with mobile phase of hexane/propanol 98:2%.

[00102] Scheme 2:

[00103] To a solution of (lR,2R,3aS,9aS)-[[2,3,3a,4,9,9a-hexahydro-2-hydroxy-l-

[(3S)-3-hydroxyoctyl]-lH-benz[f]inden-5-yl]oxy]acetic acid (treprostinil) (78.1 mg, 200 μιηο^) dissolved in 1,4-dioxane (2.0 mL) was added Amberlyst® 15 resin (2.0 g) and alcohol R2-OH (2.0 mmoles, 10 equivalents). The reaction mixture was heated to 40 °C and allowed to shake at approximately 100 rpm for 18-196 hours. Solvent was removed and the resin was washed with acetonitrile (MeCN) (3 x 3 mL). The 1,4-dioxane and MeCN extracts were combined and dried using a gentle stream of warmed N2 gas and gentle heat to yield a thick waxy solid. The crude material was dissolved in 20% "PrOH/Hexanes and submitted to preparatory HPLC purification. Solvent was removed from the purified material using a gentle stream of warmed N2 gas and gentle heat to yield an off-white waxy solid. The pure material was suspended in ethyl lactate for storage and was submitted to analytical HPLC for concentration determination. [00104] By way of example, the following compounds of Formula (A), set forth in

Table 5 were s nthesized by the method of scheme 2.

Table 5.

R2 group Compound

abbreviation

C5-TR

R _{2 =} ^^ ^ (C ₅ )

C ₄ -TR

R _{2 =} ^^ ^ (C ₄ )

C ₃ -TR

R ₂ = (C ₃ )

C ₂ -TR

R ₂ = (C ₂ )

[00105] A general diagram for synthesis of the alkyl ester of treprostinil is shown in Scheme I, below as well as Figure 1. The alcohol can be modified based on the desired alkyl ester chain length (e.g., C5-C18 alkyl esters of even or odd chain length, straight chain or branched). Other reaction conditions used to synthesize treprostinil ester prodrugs are provided in Table 6, below.

Scheme 1 : Esterification Mechanism for alkyl ester-TR Compounds

Table 6.

Entry Ester Solvent Coupling

Additive Time Reagent

1 C12TR Dioxane (2 mL/100 μιηοΐ TRP) DCC DMAP 84 h

2 C12TR 10% DMF/DCM DCC DMAP 84 h

3 C12TR Dioxane (2 mL/100 μιηοΐ TRP) Amberlyst-15 - 72 h

4 C12TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 18h

5 C14TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 18 h

6 C14TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 18 h

7 C14TR DMF DCC DMAP 18 h

8 C14TR DMF PyBOP TEA 18 h

9 C14TR DMF HATU TEA 18 h

1 l Oo

10 C14TR Dioxane (2 mL/100 μιηοΐ TRP) Amberlyst-15 h

11 5C9TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 72 h

12 5C9TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 72 h

13 5C9TR Dioxane (1 mL/100 μιηοΐ TRP) Amberlyst-15 - 168 Table 6.

Coupling

Entry Ester Solvent Additive Time

Reasent

h

14 5C9TR 10% DMF/DCM DCC DMAP 18 h

15 5C9TR 1 : 1 Dioxane:MeCN HATU - 18 h

16 5C9TR 1 : 1 Dioxane:MeCN PyBOP - 18 h

17 5C9TR DMF HATU - 18 h

18 5C9TR DMF PyBOP - 18 h

19 C16TR Dioxane (1 mL/100 μηιοΐ TRP) Amberlyst-15 - 18 h

20 C16TR DCM DCC DMAP 18 h

21 C16TR DCM PPh ₃ , DEAD - 18h

DCC = N,N'-Dicyclohexylcarbodiimide;

DMAP = 4-dimethylaminopyridine

DMF = N,N'-dimethylformamide;

HATU = l-[Bis(dimethylamino)methylene]-lH-l,2,3-triazolo[4,5-b]pyri dinium 3-oxid Hexafluorophosphate;

PyBOP = benzotriazol-l-yl-oxytripyrrolidinophosphonium hexafluorophosphate

Example 2 - Acylation of Treprostinil Derivatives

[00106] Treprostinil or treprostinil ester derivatives (e.g., derivatized with alkyl or alkenyl groups at the carboxylic acid moiety as prepared in Example 1) are acylated as follows.

[00107] The compound of Example 1 (0.05 mol) or treprostinil is dissolved in 10 mL of dichloromethane at 0 °C. Dimethylaminopyridine is added (20 mol%), and then a solution of an acyl chloride R(CO)Cl (2.1 equivalents) at 0 °C (wherein R is R5 or R ₆ as described herein) is added to the compound of Example 1 or treprostinil. The solution is allowed to stir and warm to 23 °C over 1 hour. The reaction is monitored by thin layer chromatography, and when no further change is observed, the reaction is quenched with aHC0 ₃ (sat), and the quenched mixture is extracted with dichloromethane (3 x 10 mL). The combined organic extracts are dried over anhydrous sodium sulfate, and the solvent is removed under vacuum to afford the crude product. Purification is effected by column chromatography on silica gel with 2% methanol in dichloromethane.

[00108] A general scheme for synthesis of the acylated treprostinil prodrugs and treprostinil derivative prodrugs is shown below and in Figure 2 (R ₂ is described herein, for example as H or a linear or branched alkyl group):

[00109] Other acylation techniques known in the art, including selective acylation of each of the secondary alcohols, can be employed. In addition, R ₂ can be selected such that the R2 group can be selectively removed after acylation of the secondary hydroxyl functionalities. Such protecting group strategies are well known to those skilled in the art, and are described in, e.g., Peter G.M. Wutes and Theodora W. Greene, Greene's Protective Groups in Organic Synthesis, 4th Edition, Wiley (2006), which is incorporated herein by reference in its entirety for all purposes. An exemplary scheme of such a process is shown below:

[00110] Synthesis of CiiTR-OAc:

[00111] To a solution of Hexadecyl Treprostinil (C16TR) (78.1 mg, 200 μηιο^) dissolved in 1,4-Dioxane (2.0 niL) was added triethylamine (TEA) (98 μΐ,, 700 μηιο1ε8, 3.5 equivalents), acetic anhydride (166 μί, 1,760 μηιο^, 8.8 equivalents), and a catalytic amount of dimethylaminopyridine (DMAP). The reaction mixture was allowed to shake at 40 °C for 72 hours. Solvent was removed under reduced pressure to yield a thick colorless oil. The crude material was dissolved in hexanes and washed with a solution of saturated aHC03 (3 x 5 mL). The organic layers were combined and solvent was removed using a gentle stream of warmed ₂ gas and gentle heat to yield a thick colorless oil. The crude material was dissolved in 20% "PrOH/Hexanes, passed through a 0.45 μιη syringe filter, and submitted to preparatory HPLC purification. Solvent was removed from the purified material using a gentle stream of warmed ₂ gas and gentle heat to yield a thick colorless oil. The pure material was suspended in ethyl lactate for storage and was submitted to analytical HPLC for concentration determination.

[00112] Ci ₆ -TR-OAc: 73% overall yield. The compound was also characterized by

NMR spectroscopy:

[00113] ^X H NMR (500 MHz, CDC1 ₃ ) δ 0.89 (t, J = 7.0 Hz, 6H), 1.17-1.32 (m, 33H),

1.43-1.46 (m, 2H), 1.49-1.66 (m, 8H), 1.89-1.93 (m, 1H), 1.99 (s, 3H), 2.06 (s, 3H), 2.30- 2.35 (m, 2h), 2.47 (d of d, J = 14.5 Hz, J = 6.0 Hz, 1H), 2.55 (d of d, J = 15.0 Hz, J = 6.0 Hz, 1H), 2.76 (d, of d, J = 14.5 Hz, J = 6.0 Hz, 1H), 2.90 (d of d, J = 15.0 Hz, J = 6.0 Hz, 1H), 4.19 (t, J = 7.0 Hz, 2H), 4.62 (s, 2H), 4.70-4.74 (m, 1H), 4.87 (p, J = 6.0 Hz, 1H), 6.63 (d, J = 8.0 Hz, 1H), 6.82 (d, J = 8.0 Hz, 1H), 7.08 (t, J = 8.0 Hz, 1H) ppm; ¹³ C NMR (125 MHz, CDCI ₃ ) δ 14.2, 14.3, 21.5 (2), 22.7, 22.9, 25.1, 26.0 (2), 28.3, 28.8, 29.4, 29.6, 29.7, 29.8, 29.9, 31.9, 32.1, 33.6, 33.7, 34.3, 37.8, 40.7, 49.0, 65.6, 66.2, 74.6, 79.0, 109.8, 121.8, 126.4, 127.6, 140.7, 155.1, 169.6, 171.0, 171.1 ppm.

Example 3 -Synthesis of treprostinil amide derivatives

[00114] Treprostinil is available commercially, and can be synthesized, for example, by the methods disclosed in U.S. Patent Nos. 6,765, 117 and 8,497,393. Synthesis of prostaglandin derivatives is described in U.S. Patent No. 4,668,814. The disclosures of U.S. Patent Nos. 6,765, 117; 8,497,393 and 4,668,814 are each incorporated by reference in their entireties for all purposes.

[00115] To a solution of (lR,2R,3aS,9aS)-[[2,3,3a,4,9,9a-hexahydro-2-hydroxy-l-

[(3S)-3-hydroxyoctyl]-lH-benz[f]inden-5-yl]oxy]acetic acid (i.e., treprostinil) (78.1 mg, 200 μηιο^) dissolved in 1,4-Dioxane (2.0 niL) was added triethylamine (TEA) (98 μί, 700 μηιο^, 3.5 equivalents), alkylamine Ri-NH ₂ (240 μmoles, 1.2 equivalents), and a solution of PyBOP (364 mg, 700 μιηο^, 3.5 equivalents) dissolved in 2.0 mL MeCN (acetonitrile).

[00116] The reaction mixture was heated to 40 °C and allowed to shake at approximately 100 rpm overnight. Solvent was removed under reduced pressure to yield the crude product as a thick yellow oil. The product was extracted (1-1 extraction) from the oil by repeated washings with 20% "PrOH/Hexanes (3 x 3 mL). Solvent was removed from the organic extract using a gentle stream of warmed 2 gas and gentle heat to yield a thick, slightly yellow oil. The crude material was dissolved in 20% "PrOH/Hexanes, passed through a 0.45 μιη syringe filter, and submitted to preparatory HPLC purification. Solvent was removed from the purified material using a gentle stream of warmed 2 gas and gentle heat to yield a thick, colorless oil. The pure material was suspended in ethyl lactate for storage and was submitted to analytical HPLC for concentration determination.

[00117] The following treprostinil amide derivatives of Formula B were made by the synthesis scheme provided above. (Table 6) Percentage yield is also provided in parentheses.

[00118] C ₆ -TR-A and C ₁₂ -TR-A were characterized by NMR spectroscopy.

NMR Characterization of C6-TR-A ¾ NMR (500 MHz, CDC1 ₃ ) δ 0.90 (q, J = 7.0 Hz, 6 H), 1.17 (q, J = 12.0 Hz, 1H), 1.30-1.70 (m, 18 H), 1.81-1.83 (m, 1H), 1.80-1.93 (m, 1H), 2.20 (p, J = 6.0 Hz, 1H), 2.22-2.23 (m, 1H), 2.47-2.54 (m, 2H), 2.75-2.82 (m, 2H), 3.16 (sextet, J = 4.0 Hz, 1H), 3.35 (q, J = 7.0 Hz, 2H), 3.63 (s, 1H), 3.70-3.80 (m, 1H), 4.48 (s, 2H), 6.55 (s, 1H), 6.70 (d, J = 7.5 Hz, 1H), 6.85 (d, J = 7.5 Hz, 1H), 7.11 (t, J = 7.5 Hz, 1H) ppm; ¹³ C NMR (125 MHz, CDC1 ₃ ) δ 14.2, 14.3, 22.8, 22.9, 25.6, 26.4, 26.7(2), 28.8, 29.7, 31.6, 32.1, 33.0, 33.8, 35.1, 37.7, 39.2, 41.4, 41.6, 46.5, 52.4, 68.4, 72.8, 1 10.4, 122.2, 126.8, 127.3, 141.2, 154.5, 168.7 ppm; HRMS (ESI, 2:2: 1 MeCN, MeOH, H ₂ 0): m/z = 474.35717 ([M+H] ⁺ ).

NMR Characterization of C12-TR-A

HRMS (ESI, 2:2: 1 MeCN, MeOH, H ₂ 0): m/z = 558.45099 ([M+H] ⁺ ).

[00119] While the described invention has been described with reference to the specific embodiments thereof it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adopt a particular situation, material, composition of matter, process, process step or steps, to the objective spirit and scope of the described invention. All such modifications are intended to be within the scope of the claims appended hereto.

[00120] Patents, patent applications, patent application publications, journal articles and protocols referenced herein are incorporated by reference in their entireties, for all purposes.