Search

US-20260125343-A1 - METHODS FOR PREPARING HIGH-PURITY VORINOSTAT AND PRECURSORS THEREOF

US20260125343A1US 20260125343 A1US20260125343 A1US 20260125343A1US-20260125343-A1

Abstract

The subject invention provides methods for synthesizing suberoylanilide hydroxamic acid (SAHA) and precursors thereof. These methods involve novel synthetic scheme for SAHA which eliminate purification of intermediates, and produce SAHA product in high purity and high yield, making them suitable for scale-up and GMP manufacturing of SAHA.

Inventors

  • Shaileshkumar Ramanlal Desai
  • AUTUMN R. BEAUCHAMP

Assignees

  • UNRAVEL BIOSCIENCES, INC.

Dates

Publication Date
20260507
Application Date
20251107

Claims (20)

  1. 1 . A method for preparing suberoylanilide hydroxamic acid (SAHA) from suberic acid monomethyl ester, comprising steps of: (a) halogenation of suberic acid monomethyl ester, to obtain methyl-8-halogeno-8-oxooctanoate; (b) amidation of methyl-8-halogeno-8-oxooctanoate, to obtain suberanilic acid methyl ester; and (c) hydroxylamination of suberanilic acid methyl ester, to obtain SAHA.
  2. 2 . The method of claim 1 , further comprising a step of: (d) non-chromatographic purification of SAHA.
  3. 3 . The method of claim 1 , wherein step (a) is carried out by reacting suberic acid monomethyl ester with a halogenation reagent at a molar ratio of suberic acid monomethyl ester: halogenation reagent of about 1:(1-2).
  4. 4 . The method of claim 3 , wherein the halogenation reagent is selected from chlorine (Cl 2 ), thionyl chloride (SOCl 2 ), methanesulfonyl chloride, trichloromethanesulfonyl chloride, tert-butyl hypochlorite, dichloromethyl methyl ether, methoxyacetyl chloride, oxalyl chloride ((COCl) 2 ), phosphorus pentachloride (PCl 5 ), phosphorus trichloride (PCl 3 ), and trimethylsilyl chloride.
  5. 5 . The method of claim 4 , wherein the halogenation reagent is SOCl 2 .
  6. 6 . The method of claim 1 , wherein step (a) is carried out at a temperature of about 20-60° C.
  7. 7 . The method of claim 1 , wherein step (b) is carried out by reacting methyl-8-halogeno-8-oxooctanoate with aniline in the presence of a first alkaline catalyst at a molar ratio of methyl-8-halogeno-8-oxooctanoate: aniline: first alkaline catalyst of about 1:(1-2):(1-2).
  8. 8 . The method of claim 7 , wherein step (b) is carried out by firstly mixing the first alkaline catalyst with aniline, followed by adding the mixture of the first alkaline catalyst and aniline into methyl-8-halogeno-8-oxooctanoate.
  9. 9 . The method of claim 7 , wherein the first alkaline catalyst is triethylamine.
  10. 10 . The method of claim 1 , wherein step (c) is carried out by reacting suberanilic acid methyl ester with hydroxylamine in the presence of a second alkaline catalyst at a molar ratio of suberanilic acid methyl ester: hydroxylamine: second alkaline catalyst of about 1:(1-10):(1-10).
  11. 11 . The method of claim 10 , wherein step (c) is carried out by firstly mixing the second alkaline catalyst with hydroxylamine, followed by adding suberanilic acid methyl ester into the mixture of the second alkaline catalyst and hydroxylamine.
  12. 12 . The method of claim 10 , wherein the second alkaline catalyst is sodium methylate.
  13. 13 . The method of claim 1 , wherein step (a) and step (b) comprise no chromatographic purification or non-chromatographic purification of intermediate obtained in each step.
  14. 14 . The method of claim 1 , wherein methyl-8-halogeno-8-oxooctanoate is selected from methyl-8-fluoro-8-oxooctanoate, methyl-8-chloro-8-oxooctanoate, methyl-8-bromo-8-oxooctanoate, and methyl-8-iodo-8-oxooctanoate.
  15. 15 . A method for preparing SAHA from methyl-8-halogeno-8-oxooctanoate, comprising steps of: (a) amidation of methyl-8-halogeno-8-oxooctanoate, to obtain suberanilic acid methyl ester; and (b) hydroxylamination of suberanilic acid methyl ester, to obtain SAHA.
  16. 16 . The method of claim 15 , further comprising a step of: (c) non-chromatographic purification of SAHA.
  17. 17 . The method of claim 15 , wherein methyl-8-halogeno-8-oxooctanoate is selected from methyl-8-fluoro-8-oxooctanoate, methyl-8-chloro-8-oxooctanoate, methyl-8-bromo-8-oxooctanoate, and methyl-8-iodo-8-oxooctanoate.
  18. 18 . A method for synthesizing high-purity SAHA, the method comprising: (a) mixing suberic acid monomethyl ester with a halogenation reagent to obtain methyl-8-halogeno-8-oxooctanoate; (b) adding a mixture of aniline and a first alkaline catalyst into (a) to obtain suberanilic acid methyl ester; (c) adding suberanilic acid methyl ester into a mixture of a second alkaline catalyst and hydroxylamine to obtain SAHA having a purity of at least 90%; and (d) optionally, purifying the obtained SAHA of step (c) via non-chromatographic purification to obtain high-purity SAHA having a purity of at least 99%.
  19. 19 . Suberoylanilide hydroxamic acid (SAHA) produced by the method of claim 1 .
  20. 20 . A pharmaceutical composition comprising SAHA according to claim 19 and a pharmaceutically acceptable excipient.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application Ser. No. 63/717,313, filed Nov. 7, 2024, the disclosure of which is hereby incorporated by reference in its entirety, including all figures, tables and amino acid or nucleic acid sequences. BACKGROUND OF INVENTION Vorinostat, also known as suberoylanilide hydroxamic acid (SAHA), is a small molecule inhibitor of histone deacetylases (HDACs). These enzymes play a crucial role in regulating chromatin structure and gene expression, and deregulation of HDAC activity has been implicated in various diseases including cancer. By selectively inhibiting HDACs, Vorinostat have multiple effects in vivo and in vitro, which includes arresting growth, affecting cell differentiation, and promoting the accumulation of acetylated histones, thereby altering gene transcription and inducing apoptosis in malignant cells. The inhibition of HDAC by SAHA is thought to occur through direct interaction with the catalytic site of the enzyme as demonstrated by X-ray crystallography studies, which show that Vorinostat binds to the zinc atom of the catalytic site of the HDAC enzyme with the phenyl ring of Vorinostat projecting out of the catalytic domain onto the surface of the HDAC enzyme. Vorinostat has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of cutaneous T-cell lymphoma (CTCL) in patients who have received at least one prior systemic therapy, and preclinical studies also suggest that it may have therapeutic potential in other types of cancer, including breast, prostate, lung, and colon cancer. While the synthesis of Vorinostat has been published over the last thirty years, the overall yields are generally low with varying purity levels. U.S. Pat. No. 8,450,372B2, U.S. Pat. No. 7,851,509B2, and Stowel et al. (“The Synthesis of N-hydroxy-N′-Phenyoctanediamide and its Inhibitory Effect on proliferation of AXC Rat Prostate Cancer Cells,” J. Med. Chem. 1995, 38, 1411-1413) described processes for synthesizing SAHA with suberic acid or suberanilic acid as the starting material. However, SAHA was only produced in low yields of about 24%-36%. The processes described in U.S. Pat. No. 5,369,108, Gediya et al. (“A New Simple and High-Yield Synthesis of Suberoylanilide Hydroxamic Acid and Its Inhibitory Effect Alone or in Combination with Retinoids on Proliferation of Human Prostate Cancer Cells,” J. Med. Chem. 2005, 48, 5047-5051), Truong et al. (“Modified Suberoylanilide Hydroxamic Acid Reduced Drug-Associated Immune Cell Death and Organ Damage under Lipopolysaccharide Inflammatory Challenge,” ACS Pharmacol. Transl. Sci. 2022, 5, 1128-1141), and Riva et al. (“Efficient Continuous Flow Synthesis of Hydroxamic Acids and Suberoylanilide Hydroxamic Acid Preparation,” J. Org. Chem. 2009, 74, 3540-3543), although increase the yield of SAHA to some extents, require chromatographic purification of the intermediates and/or the SAHA product, which are time-consuming, laborious, and environmentally unfriendly due to the use of large volumes of organic solvents. Thus, it is desirable to provide a new route for preparing high-purity Vorinostat with improved yields in simplified procedures, which is suitable for scale-up to produce larger quantities and Good Manufacturing Practice (GMP) manufacturing. BRIEF SUMMARY OF INVENTION The subject invention provides methods for synthesizing high-purity suberoylanilide hydroxamic acid (SAHA or Vorinostat). Advantageously, the synthesis procedure described in the present invention uses commercially available, low-cost materials (e.g., suberic acid monomethyl ester as starting material). The synthesis of Vorinostat includes easy work ups and eliminates the need to purify intermediates. A critical step in the synthesis is the generation of hydroxylamine using sodium methoxide, which avoids the use of water that typically generates poor yields. The isolated Vorinostat using this synthesis approach is produced in very high yields (80%-90%), and is a high purity material (>99%) that is suitable for use as a drug substance. In one embodiment, the present invention provides a method for preparing SAHA from suberic acid monomethyl ester, the method comprising steps of: (a) halogenation of suberic acid monomethyl ester to obtain methyl-8-halogeno-8-oxooctanoate;(b) amidation of methyl-8-halogeno-8-oxooctanoate to obtain suberanilic acid methyl ester; and(c) hydroxylamination of suberanilic acid methyl ester to obtain SAHA. In some embodiments, the method further comprises a step of: (d) non-chromatographic purification of SAHA. In some embodiments, step (a) of the method is carried out by reacting suberic acid monomethyl ester with one or more halogenation reagents in a molar ratio of suberic acid monomethyl ester: halogenation reagent of about 1:(1-2), and/or step (a) of the method is carried out at a temperature of about 20-80° C. In some embodiments, step (b) of the method is carr