Conversion of α-keto esters into β,β-difluoro-α-keto esters and corresponding acids: A simple route to a novel class of serine protease inhibitors

Article abstract of DOI:10.1021/jo00121a040

The preparation of a series of β,β-difluoro-α-keto esters and corresponding acids RCF₂COCO₂R' (R=Me, Et, i-Pr, Bn, and Ph; R'=Et and H), designed as potential inhibitors of serine proteases, is described. The standard procedure developed consists in the initial formation of an α,α- difluoro ester from an α-keto ester, followed by a simple four-step sequence involving the synthesis of hemiacetal, cyanohydrin, and α-hydroxy ester difluorinated intermediates. This method provides an easy route to β,β- difluoro-α-keto esters and corresponding acids, via 'formal' insertion of a difluoromethylene group between the R substituent and the α-carbonyl group of a generic α-keto ester.