Thiol–Ene Reaction of 1-Azabuta-1,3-dienes in Synthesis of Functionalized α-Amino Ketones and Fused Aziridines

A cascade thiol-ene reaction of 3-acyloxy-1-azabuta-1,3-dienes, formed <i>in situ</i> from 1,2,3-triazolyl esters under Rh(II) catalysis, proceeds under mild conditions to give previously unknown α-amino-α'-sulfanyl ketones. The carboxylic groups of several drugs were successfully modified by this method. When triazole was decorated with an azirinyl substituent, fused aziridines were diastereoselectively formed. Mechanistic studies testify in favor of the thiol-Michael addition mechanism and show the extremely high reactivity of 3-acyloxy-1-azabutadienes.