Synthesis of Filibuvir. Part I. Diastereoselective Preparation of a β-Hydroxy Alkynyl Oxazolidinone and Conversion to a 6,6-Disubstituted 2H-Pyranone

This is the first in a series of three papers describing the identification and development of a commercial synthesis of filibuvir (1). This contribution describes development of an Evans aldol reaction to control the tertiary alcohol stereocenter, a challenging variant of that strategy in that both reacting partners were nonstandard (acetate enolate and ketone electrophile). A sequence consisting of Sonogashira coupling, acylation and hydrogenation delivered acetate 24, and Dieckmann cyclization provided β-keto lactone 2.