Veena Upadhyay

Diastereoselective syn-epoxidation of 2-alkyl-4-enamides to epoxyamides: Synthesis of the Merck HIV-1 protease inhibitor epoxide intermediate

Abstract Reaction of 2-alkyl-4-enamides 2, 9–15 with NIS and aqueous sodium bicarbonate results in the diastereoselective formation of the corresponding iodohydrins 3, 16–22 with essentially no iodolactone by-product. This methodology has been successfully employed for the synthesis of the epoxide intermediate 4 of the orally active Merck HIV-1 protease inhibitor L-735,524.

Synthesis of the orally active spiroindoline-based growth hormone secretagogue, MK-677

Abstract The preparation of the Merck Growth Hormone Secretagogue; MK-677 is described. A Fischer indole/reduction based strategy provides the novel spiroindoline nucleus of this potent compound. This optimized sequence necessitates the isolation of only one intermediate 10 and provides MK-677 in 48% overall yield from isonipecotic acid 3.

Cyclic imidate salts in acyclic stereochemistry: Diastereoselective syn-epoxidation of 2-alkyl-4-enamides to epoxyamides

Abstract Reaction of 2-alkyl-4-enamides with 1 + and aqueous sodium bicarbonate results in the diastereoselective formation of the corresponding iodohydrins with essentially no iodolactone by-product. The reaction appears to proceed through a cyclic imidate type intermediate. This methodology has been successfully employed for the synthesis of the epoxide intermediate of the orally active HIV-1 protease inhibitor MK-639 (indinavir sulfate).

Porcine liver esterase-catalyzed enantioselective hydrolysis of a prochiral diester into its optically pure (S)-ester acid, a precursor to a growth hormone secretagogue.

A limited screen of several commercially-available and internally-produced lipases and esterases identified porcine liver esterase as a suitable biocatalyst for the enantioselective hydrolysis of a diester into its (S)-ester acid with high optical purity (99%). This (S)-ester acid is a precursor to an experimental growth hormone secretagogue. After identifying xanthan gum as the best emulsifier and optimizing the reaction conditions, hydrolysis rates of 1 g/l.h and final (S)-ester acid (ee > 99%) titers of about 8.5 g/l were routinely achieved. This process supported the production of preparative amounts of optically pure (S)-ester (ee > 99%) with a high reaction yield of 82%. Upon purification, the (S)-ester was successfully used in the subsequent synthetic steps to yield the growth hormone secretagogue.