Highly regioselective, electrophile induced cyclizations of 2-(prop-1-ynyl)benzamides

Abstract

We report an electrophile promoted, highly regioselective (∼100%) synthesis of 5-membered haloimidiates from 2-(1-alkynyl)benzamides under metal free conditions. The steric bulk in association with neighbouring group assistance at the propargylic carbon of an alkyne has been employed as the dictating factor to achieve the regioselectivity. A very broad structural diversity has been observed for propargylic alcohols and acetates, and for amide functional groups. Control experiments supported the role of the steric bulk as well as neighbouring group assistance from the oxygen atom of the substituent for the observed high regioselectivity.