Catalytic Enantioselective Synthesis of Key Propargylic Alcohol Intermediates of the Anti-HIV Drug Efavirenz

The catalytic, enantioselective synthesis of key propargylic alcohol intermediates toward the synthesis of the anti-HIV drug efavirenz is reported. Using a recently reported chiral-at-ruthenium catalyst (J. Am. Chem. Soc. 2017, 139, 4322), catalytic enantioselective alkynylations of 1-(2,5-dichlorophenyl)-2,2,2-trifluoroethanone (99% yield, 95% ee) and 1-(5-chloro-2-nitrophenyl)-2,2,2-trifluoroethanone (97% yield, 99% ee) are achieved using catalyst loadings of merely 0.2 mol % (ca. 500 TON).