New synthesis of propargylic amines from 2-(bromomethyl)aziridines. Intermediacy of 3-bromoazetidinium salts

A new, efficient, and straightforward synthesis provides propargylamines in high overall yields (64-77%) by transformation of 1-(arylmethyl)-2-(bromomethyl)aziridines into N,N-di(arylmethyl)-N-(2-propynyl)amines via N-(2,3-dibromopropyl)amines and N-(2-bromo-2-propenyl)amines. The conversion of N-(2,3-dibromopropyl)amines into N-(2-bromo-2-propenyl)amines is based on a novel analogue of the Hofmann elimination. A Yamaguchi-Hirao alkylation, a Sonogashira coupling, or a hydroarylation reaction further functionalized these propargylamines toward potentially interesting compounds for medicinal and agrochemical use.