Chandrashekar R. Elati

New Synthesis of Donepezil Through Palladium‐Catalyzed Hydrogenation Approach

Abstract A new, economical, and efficient process has been developed for large‐scale synthesis of donepezil 1, an anti‐Alzheimers drug. The process involves palladium‐catalyzed hydrogenation of (2E)‐5,6‐dimethoxy‐2‐(pyridin‐4‐ylmethylene)indan‐1‐one 6 to provide 5,6‐dimethoxy‐2‐(piperidin‐4‐ylmethyl)indan‐1‐one 8 as a key step. DRL‐IPD Communication No. 006.

Efficient Synthesis of (1R)‐[3,5‐Bis(trifluoromethyl)phenyl] Ethanol, a Key Intermediate for Aprepitant, an NK‐1 Receptor Antagonist

Abstract Enzyme‐catalyzed efficient synthesis of (1R)‐[3,5‐bis (trifluoromethyl) phenyl] ethanol (R)‐(3), a key intermediate for aprepitant, via enantioselective transesterification of racemic 1‐[3,5‐bis (trifluoromethyl) phenyl] ethanol (RS)‐3 using vinyl acetate as the acyl donor in the presence of Candida antarctica lipase‐B (CAL‐B) in an overall yield of 84% with >99% ee is described.

Novel Synthesis of Fosphenytoin: Anti-Convulsant Prodrug

Abstract A simple, new synthesis of fosphenytoin sodium 1, a prodrug, via imidate ester and employing mild reaction conditions is described.

Recycling of undesired isomers of key intermediate for aprepitant

Abstract A protocol for regeneration of key intermediate of aprepitant from its undesired diastereomers is described. This work features the recycling of at least one-third of the undesired isomers (ent-6, 7 and ent-7) to desired isomer 4 as the key early intermediate for the synthesis of aprepitant 1. The key step in our strategy involves diastereomeric salt preparation.