Efficient and scalable syntheses of nicotinoyl ribosides and reduced nicotinoyl ribosides, modified derivatives thereof, phosphorylated analogs thereof, adenylyl dinucleotide conjugates thereof, and novel crystalline forms thereof

Abstract

The present description provides methods for fabricating nicotinoyl riboside compounds or derivatives, their reduced analogs, modified derivatives, phosphorylated analogs and adenylyl dinucleotide conjugates or their salts, solvates or prodrugs and their novel crystal forms according to formula (I): where X'', Z1, Z2, n, R1, R2, R3, R4, R5, R6, R7 and R8 are described.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a crystalline form of nicotinic acid riboside and synthetic processes for the preparation thereof.BACKGROUND

[0002] The dietary vitamin B3, which encompasses nicotinamide ("Nam" or "NM"), nicotinic acid ("NA"), and nicotinamide riboside ("NR"), is a precursor to the coenzyme nicotinamide adenine dinucleotide ("NAD +< "), its phosphorylated parent ("NADP +< " or "NAD(P) +< "), and their respective reduced forms ("NADH" and "NADPH," respectively). Once converted intracellularly to NAD(P) +< and NAD(P)H, vitamin B3 metabolites are used as co-substrates in multiple intracellular protein modification processes, which control numerous essential signaling events (e.g., adenosine diphosphate ribosylation and deacetylation), and as cofactors in over 400 redox enzymatic reactions, thus controlling metabolism. This is demonstrated by a range of metabolic endpoints, which include the deacylation of key regulatory metabolic enzymes, resulting in the restoration of mitochondrial activity and oxygen consumption. Critically, mitochondrial dysfunction and cellular impairment have been correlated to the depletion of the NAD(P)(H)-cofactor pool, when the NAD(P)(H)-cofactor pool is present in sub-optimal intracellular concentrations. Vitamin B3 deficiency yields to evidenced compromised cellular activity through NAD(P) +< depletion, and the beneficial effect of additional NAD(P) +< bioavailability through NA, Nam, NR, and nicotinamide mononucleotide ("NMN") supplementation is primarily observed in cells and tissues where metabolism and mitochondrial function have been compromised.

[0003] Despite extensive optimization of solution-based methodologies over many years for nucleotide preparation, difficulties and issues remain in the syntheses of nicotinoyl ribosides, the monophosphorylation of active hydroxyl groups thereof, and subsequent conjugation thereof, with respect to low yields and product stability and isolation from polar solvents. The current methodologies are also plagued by atom and energy inefficiency due, for example, to the use of large solvent excesses and the need for temperature-controlled reaction conditions.

[0004] The reported syntheses of nicotinamide riboside (NR) are becoming more scalable, but use corrosive and expensive reagents, and lengthy deprotection steps, and thus still display batch-to-batch quality variation, thereby presenting difficulties in maintaining good standards.

[0005] Partially protected nucleosides and nucleotides have found broad-ranging application in order to achieve improved bioavailability of the nucleoside and nucleotide parents. Such partial protection includes hydroxyl modifications with ester, carboxylate, and acetyl groups, in addition to the introduction of hydrolyzable phosphoramidate or mixed anhydride modification of the phosphate monoesters in the form of Protides and CycloSal derivatives. While the former type of protection has become more scalable, the modifications at the phosphorus center remain difficult to accomplish at scale, particularly on nucleosidic entities that are highly sensitive to changes in pH and that are readily degraded by heat.

[0006] Reduced nicotinamide riboside ("NRH") has been consistently shown to be more efficient at increasing intracellular NAD +< levels, and surpasses nicotinamide riboside (NR) in that respect. While physiological and potentially therapeutic roles have not yet been examined due to a lack of material accessible in sufficient quantities for broad-ranging studies, it is anticipated that the phosphorylated forms of NRH and reduced nicotinic acid riboside ("NARH"), or derivatives thereof, could also have similar NAD +< -boosting capacities.

[0007] The reported syntheses of reduced nicotinamide riboside (NRH) are becoming more widely available but remain conducted on small scales, using corrosive and expensive reagents, and lengthy deprotection steps, and thus still display batch-to-batch quality variation, thereby presenting difficulties in maintaining good standards. In the current description, reduced nicotinamide riboside (NRH) generally refers to "reduced pyridine" nucleus, more specifically, the 1,4-dihydropyridine compounds.

[0008] Synthetically, the preparation of 5'-nucleotides remains time-consuming, atom-inefficient, and costly, due to the need for numerous protection and deprotection steps. In these preparation methods, the chlorodialkylphosphate, tetraalkylpyrophosphate, chlorophosphite, or phosphoramidite reagents required are also expensive starting materials by virtue of their chemical functionalization and chemical instability, and therefore, consequently associated synthetic difficulties. Phosphorylation reaction conditions are difficult to control and often use non-approved or toxic organic solvents, thus limiting the market of the manufactured compounds.

[0009] One known alternative approach to the protection / deprotection method is to use phosphorus oxychloride (P(O)Cl 3 ) (i.e., Yoshikawa conditions), however there are still drawbacks to this method, as follows. While not being bound by theory, in this method, polar trialkyl phosphate solvents, such as P(O)(OMe) 3 , are used in a large excess, which are believed to enhance reaction rates while limiting the undesirable reactivity of P(O)Cl 3 as a chlorinating agent. Thus, it is believed that use of excess P(O)Cl 3 / P(O)(OR) 3 is a better combination for the chemoselective 5'-O-phosphorylation of unprotected ribosides. However, the use of trialkyl phosphate solvents, such as P(O)(OMe) 3 , precludes their implementation for the preparation of materials for eventual human use, as this class of solvent is highly toxic (known carcinogen, non-GRAS approved) and is difficult to remove from the final polar products. See M. Yoshikawa et al., Studies of Phosphorylation. III. Selective Phosphorylation of Unprotected Nucleosides, 42 BULL. CHEM. Soc. JAPAN 3505 (1969); Jaemoon Lee et al., A chemical synthesis of nicotinamide adenine dinucleotide (NAD+), CHEM. COMMUN. 729 (1999).

[0010] Nicotinamide adenine dinucleotide (NAD +< ) remains an expensive cofactor, and its commercial availability is simply limited by its complex chemical nature and the highly reactive pyrophosphate bond, which is challenging to form at scale.

[0011] Nicotinoyl ribosides such as nicotinamide riboside (NR) and nicotinic acid riboside ("NAR"), nicotinamide mononucleotide (NMN), and NAD +< are viewed as useful bioavailable precursors of the NAD(P)(H) pool to combat and treat a broad range of non-communicable diseases, in particular those associated with mitochondrial dysfunction and impaired cellular metabolism. Optimizing the large-scale syntheses of these vitamin B3 derivatives is therefore highly valuable to make these compounds more widely available to society both in terms of nutraceutical and pharmaceutical entities.

[0012] Reduced nicotinoyl ribosides, such as reduced nicotinamide riboside (NRH), reduced nicotinic acid riboside (NARH), reduced nicotinamide mononucleotide ("NMNH"), reduced nicotinic acid mononucleotide ("NaMNH"), and reduced nicotinamide adenine dinucleotide ("NADH") are viewed as useful bioavailable precursors of the NAD(P)(H) pool to combat and treat a broad range of non-communicable diseases, in particular those associated with mitochondrial dysfunction and impaired cellular metabolism. Optimizing the large-scale syntheses of these vitamin B3 derivatives is therefore highly valuable to make these compounds more widely available to society, both in terms of nutraceutical and pharmaceutical entities.

[0013] Crystalline forms of useful molecules can have advantageous properties relative to the respective amorphous forms of such molecules. For example, crystal forms are often easier to handle and process, for example, when preparing compositions that include the crystal forms. Crystalline forms typically have greater storage stability and are more amenable to purification. The use of a crystalline form of a pharmaceutically useful compound can also improve the performance characteristics of a pharmaceutical product that includes the compound. Obtaining the crystalline form also serves to enlarge the repertoire of materials that formulation scientists have available for formulation optimization, for example by providing a product with different properties, e.g., better processing or handling characteristics, improved dissolution profile, or improved shelf-life.

[0014] WO 2016 / 014927 A2 describes crystalline forms of nicotinamide riboside, including a Form I of nicotinamide riboside chloride. Also disclosed are pharmaceutical compositions comprising the crystalline Form I of nicotinamide riboside chloride, and methods of producing such pharmaceutical compositions.

[0015] WO 2016 / 144660 A1 describes crystalline forms of nicotinamide riboside, including a Form II of nicotinamide riboside chloride. Also disclosed are pharmaceutical compositions comprising the crystalline Form II of nicotinamide riboside chloride, and methods of producing such pharmaceutical compositions.

[0016] US 2012 / 172584 A1 compositions of nicotinoyl ribosides and nicotinamide riboside derivatives and their methods of use. In further embodiments, the disclosure relates to methods of using nicotinoyl ribosides and nicotinamide riboside derivatives that promote the increase of intracellular levels of nicotinamide adenine dinucleotide (NAD+) in cells and tissues for improving cell and tissue survival.

[0017] WO2016 / 149395 A1 discloses nicotinic acid riboside under amorphous form.

[0018] In view of the above, there is a need for processes that are atom-efficient in terms of reagent and solvent equivalency, that bypass the need for polar, non-GRAS ("generally recognized as safe") solvents, that are versatile in terms of limitations associated with solubility and reagent mixing, that are time- and energy-efficient, and that provide efficient, practical, and scalable methods for the preparation of nicotinoyl ribosides, reduced nicotinoyl ribosides, modified derivatives thereof, phosphorylated analogs thereof, and adenylyl dinucleotide conjugates thereof.

[0019] In view of the above, there is a need for novel crystalline forms of nicotinoyl ribosides, reduced nicotinoyl ribosides, modified derivatives thereof, phosphorylated analogs thereof, and adenylyl dinucleotide conjugates thereof.SUMMARY OF THE INVENTION

[0020] The invention is defined in the appended claims. Any disclosure going beyond the scope of said claims is only intended for illustrative purposes and should not be construed as being part of the invention.

[0021] Disclosed but not claimed are scalable methods of preparation of nicotinic acid riboside (NAR) by liquid assisted mixing and / or extrusion.

[0022] Disclosed but not claimed are and semi-continuous processes that enable the production of nicotinic acid riboside (NAR), whereby the use of solvents is kept to a minimum, and whereby conversion and reaction times are optimized by the use of sealed conditions, continuous liquid-liquid extraction, and / or mechanochemistry, and an optimized purification sequence.

[0023] Provided is a crystalline Form I of nicotinic acid riboside (NAR), according to formula (VIII):

[0024] The above crystalline Form I is characterized by a powder X-ray diffraction pattern having peaks at 19.2, 21.6, and 26.4 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks at 15.7, 19.2, 21.6, 26.4, and 28.9 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder x-ray diffraction pattern having peaks at 12.8, 13.2, 15.7, 19.2, 20.5, 21.6, 26.4, 28.3, and 28.9 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern substantially as shown in Figure 17. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 4 ± 0.2 degrees two theta.

[0025] In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, and 773.3 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, and 1359.6 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, 1359.6, 1579.4, 1612.2, 1639.2 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum substantially as shown in Figure 23. In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks substantially as provided in Table 5 ± 0.2 cm -1< .

[0026] In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram substantially as shown in Figure 32. In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset mperature of 156° C ± 2° C. In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with a peak temperature of 164° C ± 2° C. IN yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 156° C ± 2° C and a peak temperature of 164° C ± 2° C.

[0027] The crystalline NAR Form I can be prepared by a method (not claimed) that can includes the steps of: (a) dissolving the compound or derivative having formula (VIII), or salt or solvate thereof, in a volume of methanol; (b) adding a volume of acetone, of an equal volume to the volume of methanol, to the compound or derivative having formula (VIII), or salt or solvate thereof, in the volume of methanol; (c) precipitating the crystalline Form I; and (d) isolating the crystalline Form I.

[0028] In an alternative embodiment of the above method of preparing crystalline NAR Form I, the method (not claimed) can further include the steps of: (a1) providing a compound or derivative having formula (1a), or a salt thereof: wherein Z 2< is oxygen; n is 0; R 1< is hydrogen; wherein the compound or derivative having formula (1a) may optionally take the form of the carboxylate anion conjugate base species of the compound or derivative having formula (1a), further optionally associated with a positively charged counterion selected from the group consisting of calcium, magnesium, potassium, sodium, zinc, and ammonium cations; each of R 2< , R 3< , R 4< , and R 5< is hydrogen; (a2) treating the compound or derivative having formula (1a), or salt thereof, with excess trimethylsilylating reagent(s) so as to produce a compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group; (a3) removing the trimethylsilylating reagent(s); (a4) treating the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, with a molar equivalent amount of a compound or derivative having formula (2), or a salt thereof, and a molar equivalent amount of TMSOTf, in an organic solvent co-reagent: wherein X' is selected from the group consisting of fluoro, chloro, bromo, iodo, HCO 2 , acetoxy, propionoxy, butyroxy, glutamyloxy, aspartyloxy, ascorbyloxy, benzoxy, HOCO 2 , citryloxy, carbamyloxy, gluconyloxy, lactyloxy, succinyloxy, sulfoxy, trifluoromethanesulfoxy, tribromomethanesulfoxy, tribromomethanesulfoxy, and trifluoroacetoxy; each of R 6< , R 7< , and R 8< is -C(O)R'; R' is methyl; (a5) processing the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, the compound or derivative having formula (2), or salt thereof, the TMSOTf, and the organic solvent co-reagent so as to produce the compound or derivative having formula (Ia), or salt or solvate thereof, wherein R 1< is a TMS group; (a6) adding water to, optionally, the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, optionally, the compound or derivative having formula (2), or salt thereof, the TMSOTf, the organic solvent co-reagent, and the compound or derivative having formula (Ia), or salt or solvate thereof, optionally wherein R 1< is a TMS group; (a7) isolating the compound or derivative having formula (Ia), or salt or solvate thereof; (a8) dissolving the compound or derivative having formula (Ia), or salt or solvate thereof, in methanol, in a gas pressure tube; (a9) cooling the solution of the compound or derivative having formula (Ia), or salt or solvate thereof, in methanol, to -78° C; (a10) bubbling ammonia gas into the solution of the compound or derivative having formula (Ia), or salt or solvate thereof, in methanol; (a11) sealing the pressure tube; (a12) raising the temperature to -20° C; (a13) cooling the pressure tube at -20° C for about 12 hours to about 4 days, so as to produce a compound or derivative having formula (VIII), or salt or solvate thereof; (a14) unsealing the gas pressure tube; and (a15) isolating the compound or derivative having formula (VIII), or salt or solvate thereof; wherein the steps (a1) to (a15) are performed sequentially, before step (a).In an embodiment, the present disclosure provides a novel crystalline Form I of nicotinic acid riboside triacetate (NARTA), according to formula (X), which is not claimed:

[0029] In another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, and 20.5 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, 16.5, 16.8, and 20.5 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, 12.0, 16.5, 16.8, 19.9, 20.5, 23.7, and 23.9 degrees two theta ± 0.2 degrees two theta. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern substantially as shown in Figure 19. In yet another embodiment, the above crystalline Form I can be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 9 ± 0.2 degrees two theta.

[0030] In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 603.6, 684.6, 763.7, and 781.0 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 603.6, 684.6, 763.7, 781.0, 858.2, 894.8, 921.8, 1026.0, 1051.0, and 1066.5 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks at 603.6, 684.6, 763.7, 781.0, 858.2, 894.8, 921.8, 1026.0, 1051.0, 1066.5, 1610.3, 1639.2, and 1743.4 cm -1< ± 0.2 cm -1< . In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum substantially as shown in Figure 25. In yet another embodiment, the above crystalline Form I can be characterized by an IR spectrum having peaks substantially as provided in Table 10 ± 0.2 cm -1< .

[0031] In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram substantially as shown in Figure 33. In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 148° C ± 2° C. In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with a peak temperature of 152° C ± 2° C. In yet another embodiment, the above crystalline Form I can be characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 148° C ± 2° C and a peak temperature of 152° C ± 2° C.

[0032] In yet another embodiment, the above crystalline Form I can be prepared by a method that can include the steps of: (a) dissolving the compound or derivative having formula (X), or salt or solvate thereof; (b) adding a volume of acetone, of an equal volume to the volume of methanol, to the compound or derivative having formula (X), or salt or solvate thereof, in the volume of methanol; (c) precipitating the crystalline Form I; and (d) isolating the crystalline Form I.

[0033] In yet another embodiment, the above crystalline Form I can be prepared by a method that can further include the steps of: (a) providing a compound or derivative having formula (1a), or a salt thereof: wherein Z 2< is oxygen; n is 0; R 1< is hydrogen; wherein the compound or derivative having formula (1a) may optionally take the form of the carboxylate anion conjugate species of the compound or derivative having formula (1a), further optionally associated with a positively charged counterion selected from the group consisting of calcium, magnesium, potassium, sodium, zinc, and ammonium cations; each of R 2< , R 3< , R 4< , and R 5< is hydrogen; (a2) treating the compound or derivative having formula (1a), or salt thereof, with excess trimethylsilylating reagent(s) so as to produce a compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group; (a3) removing the trimethylsilylating reagent(s); (a4) treating the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, with a molar equivalent amount of a compound or derivative having formula (2), or a salt thereof, in an organic solvent co-reagent; wherein X' is selected from the group consisting of fluoro, chloro, bromo, iodo, HCO 2 , acetoxy, propionoxy, butyroxy, glutamyloxy, aspartyloxy, ascorbyloxy, benzoxy, HOCO 2 , citryloxy, carbamyloxy, gluconyloxy, lactyloxy, succinyloxy, sulfoxy, trifluoromethanesulfoxy, trichloromethanesulfoxy, tribromomethanesulfoxy, and trifluoroacetoxy; each of R 6< , R 7< , and R 8< is -C(O)R'; R' is methyl; (a5) processing the compound or derivative having formula (1a), or salt thereof, wherien R 1< is a TMS group, the compound or derivative having formula (2), or salt thereof, and the organic solvent co-reagent so as to produce the compound or derivative having formula (Ia), or salt or solvate thereof, wherein R 1< is a TMS group; (a6) adding water to, optionally, the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, optionally, the compound or derivative having formula (2), or salt thereof, the organic solvent co-reagent, and the compound or derivative having formula (Ia), or salt or solvate thereof, optionally wherein R 1< is a TMS group; (a7) adjusting the pH of the aqueous phase; (a8) separating the organic phase from the aqueous phase; and (a9) freeze-drying the aqueous phase to provide the compound or derivative having formula (Ia), or salt or solvate thereof; wherein the steps (a1) to (a9) are performed sequentially, before step (a).

[0034] In yet another embodiment of the above method, the compound or derivative having formula (1a), or salt thereof, wherein R 1< is a TMS group, the compound or derivative having formula (2), or salt thereof, and the organic solvent co-reagent are further treated with a Lewis acid in step (a4).BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 provides an X-ray powder diffraction pattern for the presently disclosed Form I of crystalline nicotinic acid riboside (NAR), the compound having formula (VIII), prepared according to an embodiment of the presently disclosed methods for the preparation of a compound or derivative having general formula (Ia-H), or a salt, solvate, or prodrug thereof, wherein R 6< , R 7< , and R 8< are each hydrogen. FIG. 2 provides an X-ray powder diffraction pattern for the presently disclosed Form I of crystalline nicotinic acid riboside triacetate (1-(2',3',5'-triacetyl-beta-D-ribofuranosyl)-nicotinic acid, "NAR triacetate," or "NARTA"), the compound having formula (X), prepared according to an embodiment of the presently disclosed methods for the preparation of a compound or derivative having general formula (Ia), or a salt, solvate, or prodrug thereof. FIG. 3 provides a solid state IR spectrum for the presently disclosed Form I of crystalline nicotinic acid riboside (NAR), the compound having formula (VIII). FIG. 4 provides a solid state IR spectrum for the presently disclosed Form I of crystalline nicotinic acid riboside triacetate (1-(2',3',5'-triacetyl-beta-D-ribofuranosyl)-nicotinic acid, "NAR triacetate," or "NARTA"), the compound having formula (X). FIG. 5 provides a DSC thermogram for a sample of the presently disclosed Form I of crystalline nicotinic acid riboside (NAR), the compound having formula (VIII), which was heated at a rate of 10 K / min. FIG. 6 provides a DSC thermogram for a sample of the presently disclosed Form I of crystalline nicotinic acid riboside triacetate (1-(2',3',5'-triacetyl-beta-D-ribofuranosyl)-nicotinic acid, "NAR triacetate," or "NARTA"), the compound having formula (X), which was heated at a rate of 10 K / min. FIG. 7 depicts a 19< F NMR spectrum of product nicotinic acid riboside (NAR), the compound having formula (VIII), prepared according to an embodiment of the described methods for the preparation of a compound or derivative having general formula (Ia-H), or a salt, solvate, or prodrug thereof, wherein R 6< , R 7< , and R 8< are each hydrogen, showing the absence of any fluorine shifts corresponding to the absence of any fluorine-containing species in the product, and wherein the method includes the use of a Lewis acid including a trifluoromethanesulfonate ("triflate") species. FIG. 8 depicts a 19< F NMR spectrum of product nicotinic acid riboside triacetate (NARTA), the compound having formula (X), prepared according to an embodiment of the described methods for the preparation of a compound or derivative having general formula (Ia), or a salt, solvate, or prodrug thereof, showing the absence of any fluorine shifts corresponding to the absence of any fluorine-containing species in the product, and wherein the method includes the use of a Lewis acid including a trifluoromethanesulfonate ("triflate") species. DETAILED DESCRIPTION

[0036] The present disclosure relates to crystalline forms of nicotinic acid riboside (NAR), comprising "Form I" of nicotinic acid riboside (NAR), and methods of preparation thereof.

[0037] In yet another embodiment, the present disclosure relates to crystalline forms of nicotinic acid riboside triacetate (1-(2',3',5'-triacetyl-beta-D-ribofuranosyl)-nicotininic acid, "NAR triacetate," or "NARTA"), including, but not limited to, a "Form I" of nicotinic acid riboside triacetate (NARTA), and methods of preparation thereof. Form I of nicotinic acid riboside triacetate is not claimed but can be reacted to form the claimed Form I of nicotinic acid riboside.D. Synthetic preparation of nicotinic acid riboside (Compound 4): Compound of formula (Ia-H): R 1< = hydrogen, n = 0, Z 2< = oxygen, R 2< = R 3< = R 4< = R 5< = R 6< = R 7< = R 8< = hydrogen.

[0038]

[0039] To a dry round-bottom flask was added nicotinic acid (40 g, 324.9 mmol, 1.0 equiv.), followed by HMDS (200 g, 1239.2 mmol, 3.8 equiv.) and a catalytic amount of ammonium sulphate (1% mol equiv.). The suspension was then heated to reflux under an atmosphere of nitrogen gas for 12 hours. The solution was cooled to room temperature, and the excess HMDS was removed under reduced pressure. The gummy oil was then resuspended in freshly distilled dichloroethane (150 mL), followed by the addition of riboside tetraacetate (103 g, 322.6 mmol, 1.0 equiv.) and TMSOTf (58 mL, 322.6 mmol, 1.0 equiv.). The solution was heated to 40° C and left stirring overnight under nitrogen gas. After NMR analysis indicated that the reaction had reached completion, the solution was allowed to cool to room temperature. With intensive stirring, 100 mL of distilled water was added followed by the rapid addition of a saturated NaHCO 3 solution (approximately 50 mL). The pH was adjusted to approximately 6, and the organic phase was separated, then the aqueous layer was washed three additional times with dichloromethane (100 mL), the aqueous layer was then frozen and freeze-dried to give an off-white solid, which was characterized infra as crystalline Form I of nicotinic acid riboside triacetate (NARTA) without further purification. In a glass pressure tube, the crude was suspended into methanol, and ammonia gas was bubbled into the solution for five minutes with the temperature held at -78° C. The tube was then sealed and stored at -20° C for 4 days, after which the solution was concentrated under reduced pressure. The crude was then resolubilized into methanol and an equivalent volume of acetone was added, causing a phase separation to occur. The precipitate was then filtered under reduced pressure and washed an additional five times with cold methanol to yield nicotinic acid riboside (Compound 4) as a free-flowing orange powder in 74% yield.

[0040] 1< H NMR (400 MHz, D 2 O): δ ppm 9.33 (br s, 1H, aromatic), 9.02 (d, J = 6.3 Hz, 1H, aromatic), 8.81 (dt, J = 8.0, 1.3 Hz, 1H, aromatic), 8.06 (dd, J = 8.0, 6.3 Hz, 1H, aromatic), 6.09 (d, J = 4.8 Hz, 1H, H-1 (anomeric)), 4.37 (dd, J = 4.8, 4.5 Hz, 1H, H-2), 4.37 (dd, J = 4.8, 4.5 Hz, 1H, H-2), 4.33-4.36 (m, 1H, H-4), 4.23 (t, J = 4.5 Hz, 1H, H-3), 3.91 (AB X , J A , A' = 12.9 Hz, J A,B = 3.9 Hz, 1H, H-5), 3.78 (AB X , J A , A' = 12.9 Hz, J A,B = 2.9 Hz, 1H, H-5'). 13< C NMR (100 MHz, D 2 O): δ ppm 167.5 (COOH), 146.9, 141.3, 140.9, 137.3, 127.9 (aromatic), 99.6 (C-1 (anomeric)), 87.6 (C-4), 77.5 (C-2), 70.0 (C-3), 60.4 (C-5). HRMS (ES, M + H +< ) calculated 256.0821 for C 11 H 13 NO 6 , found 256.0818.

[0041] Nicotinic acid riboside (Compound 4) was shown to be free of triflate according to 19< F NMR, as shown in FIG. 7. Crude nicotinic acid riboside triacetate (NARTA) was shown to be free of triflate according to 19< F NMR, as shown in FIG. 8.

[0042] The crystalline Form I of nicotinic acid riboside (NAR, Compound 4) may be characterized by a powder X-ray diffraction pattern having peaks at 19.2, 21.6, and 26.4 degrees two theta ± 0.2 degrees two theta. The crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks at 15.7, 19.2, 21.6, 26.4, and 28.9 degrees two theta ± 0.2 degrees two theta. The crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks at 12.8, 13.2, 15.7, 19.2, 20.5, 21.6, 26.4, 28.3, 28.9 degrees two theta ± 0.2 degrees two theta.

[0043] In other embodiments, the crystalline Form I of nicotinic acid riboside (NAR) may be characterized by a powder X-ray diffraction pattern substantially as shown in FIG. 1. The crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 4, below, ± 0.2 degrees two theta. TABLE 4Peak No.Pos. [°2Th.]d-spacing [Å]Height [cts]I / I max [%]110.6348.3123219212.8086.90671120313.1796.71377822414.2986.189438711515.6695.651189253616.9465.22834610718.1374.8872768819.2374.613542100920.5484.31891233351021.55974.11843298931124.0193.702541151225.763.45615041326.3873.3753098871427.873.19816551528.33.151932261628.8743.08971425401730.262.95110931830.9832.88427681931.6432.8253339102032.22.77712842134.3362.6096602172234.9312.5665380112335.512.52611832435.92.499423772536.752.44414842638.532.33516552739.0422.3052384112839.952.2559732940.842.20812133043.9842.05721663145.042.011310133245.4121.99561244

[0044] The crystalline Form I of nicotinic acid riboside (NAR, Compound 4) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 534.2, 680.8, 754.0, and 773.3 cm -1< ± 0.2 cm -1< . The crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, and 1359.6 cm -1< ± 0.2 cm -1< . The crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, 1359.6, 1579.4, 1612.2, and 1639.2 cm -1< ± 0.2 cm -1< . In certain embodiments, the crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a solid-state IR spectrum substantially as shown in FIG. 3. In further embodiments, the crystalline Form I of nicotinic acid riboside (NAR) may also or alternatively be characterized by a solid-state IR spectrum having peaks substantially as provided in Table 5, below, ± 0.2 cm -1< . TABLE 5IR (cm -1< )3257.233091.383060.533041.242950.601639.221612.231579.441492.661465.661359.591346.091322.951309.451267.021214.951182.171135.891114.671087.671052.96979.67948.82923.75867.82773.33754.04680.76632.55620.98534.19

[0045] In another embodiment, crystalline Form I of nicotinic acid riboside (NAR) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 156° C ± 2° C.

[0046] In yet another embodiment, crystalline Form I of nicotinic acid riboside (NAR) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with a peak temperature of 164° C ± 2° C.

[0047] In yet another embodiment, crystalline Form I of nicotinic acid riboside (NAR) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 156° C ± 2° C, a peak temperature of 164° C ± 2° C, or both.

[0048] In yet another embodiment, crystalline Form I of nicotinic acid riboside (NAR) may be characterized by a DSC thermogram substantially as shown in FIG. 5.Characterization Data for Nicotinic Acid Riboside Triacetate (NARTA)

[0049] 1< H NMR (D 2 O, 400 MHz): δ ppm 9.28 (s, 1H, aromatic), 8.98 (d, J = 6.1 Hz, 1H, aromatic), 8.83 (d, J = 7.8 Hz, 1H, aromatic), 8.06 (dd, J = 7.8, 6.1 Hz, 1H, aromatic), 6.46 (d, J = 3.7 Hz, 1H, H-1 (anomeric)), 5.46 (t, J = 4.7 Hz, 1H, H-3), 5.37 (t, J = 5.4 Hz, 1H, H-2), 4.77-4.80 (m, 1H, H-4), 4.41-4.44 (m, 2H, H-5), 2.05 (s, 3H, OAc), 2.03 (s, 3H, OAc), 1.99 (s, 3H, OAc). 13< C NMR (D 2 O, 100 MHz): δ ppm 176.7, 173.5, 172.5, 164.6 (3 x C(=O)CH 3 , COOH), 148.4, 143.7, 141.7, 133.0, 128.8 (aromatic), 97.4 (C-1 (anomeric)), 82.3 (C-3), 76.6 (C-2), 69.7 (C-5), 62.8 (C-4), 20.3 (s, OAc), 20.0 (s, OAc), 19.9 (s, OAc).Crystalline Form I of Nicotinic Acid Riboside Triacetate (NARTA)

[0050] Crystalline Form I of nicotinic acid riboside triacetate (NARTA) may be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, and 20.5 degrees two theta ± 0.2 degrees two theta. The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, 16.5, 16.8, and 20.5 degrees two theta ± 0.2 degrees two theta. The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks at 4.7, 9.5, 12.0, 16.5, 16.8, 19.9, 20.5, 23.7, and 23.9 degrees two theta ± 0.2 degrees two theta.

[0051] In other embodiments, the crystalline Form I of nicotinic acid riboside triacetate (NARTA) may be characterized by a powder X-ray diffraction pattern substantially as shown in FIG. 2. The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a powder X-ray diffraction pattern having peaks substantially as provided in Table 9, below, ± 0.2 degrees two theta. TABLE 9Peak No.Pos. [°2Th.]d-spacing [Å]Height [cts]I / I max [%]14.71518.72523659028.19510.783571439.4649.338181969412.0397.34660823512.5527.04638315613.7876.4181405714.236.21950219814.586.071686916.4865.373848321016.7635.2851337511117.1575.164357141218.0794.903313121319.044.65811441419.8864.4612573221520.4764.333926361001623.693.7527683261723.8833.7228653251824.453.63816461925.7243.460421782026.6533.342333132127.7393.2134299112228.823.09519172330.0329.7319672431.3242.853316762533.622.66313652634.782.57810042726.7362.4445813

[0052] The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 603.6, 684.6, 763.7, and 781.0 cm -1< ± 0.2 cm -1< . The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 603.6, 684.6, 763.7, 781.0, 858.2, 894.8, 921.8, 1026.0, 1051.0, and 1066.5 cm -1< ± 0.2 cm -1< . The crystalline Form I of nicotinic acid riboside triacetate (NARTA) may also or alternatively be characterized by a solid-state IR spectrum having peaks at 603.6, 684.6, 763.7, 781.0, 858.2, 894.8, 921.8, 1026.0, 1051.0, 1066.5, 1610.3, 1639.2, and 1743.4 cm -1< ± 0.2 cm -1< . In certain embodiments, the crystalline Form I of nicotinic acid riboside triacetate (NARTA) may be characterized by a solid-state IR spectrum substantially as shown in FIG. 4. In further embodiments, the crystalline Form I of nicotinic acid riboside triacetate (NARTA) may be characterized by a solid-state IR spectrum having peaks substantially as provided in Table 10, below, ± 0.2 cm -1< . TABLE 10IR (cm -1< )3064.383041.242954.461743.361639.221610.301346.091226.531110.821097.321066.461051.031025.96921.82894.82858.18781.04763.69684.62603.62

[0053] In another embodiment, crystalline Form I of nicotinic acid riboside triacetate (NARTA) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 148° C ± 2° C.

[0054] In yet another embodiment, crystalline Form I of nicotinic acid riboside triacetate (NARTA) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with a peak temperature of 152° C ± 2° C.

[0055] In yet another embodiment, crystalline Form I of nicotinic acid riboside triacetate (NARTA) is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 148° C ± 2° C, a peak temperature of 152° C ± 2° C, or both.

[0056] In yet another embodiment, crystalline Form I of nicotinic acid riboside triacetate (NARTA) is characterized by a DSC thermogram substantially as shown in FIG. 6. Form I of nicotinic acid riboside triacetate is not claimed but can be reacted to form the claimed Form I of nicotinic acid riboside.

Claims

1. A crystalline Form I of nicotinic acid riboside according to formula (VIII): wherein the crystalline Form I is characterized by a powder X-ray diffraction pattern having peaks at 19.2, 21.6, and 26.4 degrees two theta ± 0.2 degrees two theta.

2. The crystalline Form I of claim 1 that is characterized by a powder X-ray diffraction pattern having peaks at 15.7, 19.2, 21.6, 26.4, and 28.9 degrees two theta ± 0.2 degrees two theta.

3. The crystalline Form I of claim 1 that is characterized by a powder X-ray diffraction pattern having peaks at 12.8, 13.2, 15.7, 19.2, 20.5, 21.6, 26.4, 28.3, and 28.9 degrees two theta ± 0.2 degrees two theta.

4. The crystalline Form I of claim 1 that is characterized by a powder X-ray diffraction pattern having peaks at 10.634, 12.808, 13.179, 14.298, 15.669, 16.946, 18.137, 19.237, 20.548, 21.5597, 24.019, 25.76, 26.387, 27.87, 28.3, 28.874, 30.26, 30.983, 31.643, 32.2, 34.336, 34.931, 35.51, 35.9, 36.75, 38.53, 39.042, 39.95, 40.84, 43.984, 45.04, 45.412 ± 0.2 degrees two theta.

5. The crystalline Form I of claim 1 that is characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, and 773.3 cm-1 ± 0.2 cm-1.

6. The crystalline Form I of claim 1 that is <b>characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, and 1359.6 cm-1 ± 0.2 cm-1; or that is characterized by an IR spectrum having peaks at 534.2, 680.8, 754.0, 773.3, 1087.7, 1114.7, 1359.6, 1579.4, 1612.2, and 1639.2 cm-1 ± 0.2 cm-1.

7. The crystalline Form I of claim 1 that is characterized by an IR spectrum having peaks at 3257.23, 3091.38, 3060.53, 3041.24, 2950.60, 1639.22, 1612.23, 1579.44, 1492.66, 1465.66, 1359.59, 1346.09, 1322.95, 1309.45, 1267.02, 1214.95, 1182.17, 1135.89, 1114.67, 1087.67, 1052.96, 979.67, 948.82, 923.75, 867.82, 773.33, 754.04, 680.76, 632.55, 620.98, 534.19 cm-1 ± 0.2 cm-1.

8. The crystalline Form I of claim 1 that is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 156° C ± 2° C.

9. The crystalline Form I of claim 1 that is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with a peak temperature of 164° C ± 2° C; or that is characterized by a DSC thermogram obtained using a heating rate of 10 K / min comprising an endothermic event with an onset temperature of 156° C ± 2° C and a peak temperature of 164° C ± 2° C.