Catalytic asymmetric brominative dearomatization reaction of benzofurans

Abstract

A catalytic asymmetric brominative dearomatization reaction of benzofuran derivatives was achieved by using hydroquinidine 1,4-phthalazinediyl diether [(DHQ)2PHAL] as the catalyst and N-bromoacetamide (NBAc) as the brominating reagent. A series of brominated spiro[benzofuran-2,5'-oxazoles] bearing two contiguous stereogenic centers were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 97% ee).