Organocatalytic enantioselective C–H allenylation of carbazoles with propargylic alcohols via remote 1,8-conjugate addition

Abstract

An efficient method for the remote asymmetric C–H allenylation of carbazoles with propargylic alcohols via 1,8-conjugate addition has been developed. This strategy employs aza-para-quinone methides, generated in situ from α-(4-aminophenyl) propargylic alcohols, as versatile electrophilic intermediates. With chiral phosphoric acid catalysis, a wide range of C3-allenylated carbazole derivatives were obtained in high yields with excellent enantioselectivities (23 examples, up to 93% yield and 97% ee).