Heteroannulation through copper catalysis: a novel and highly regio- and stereoselective cyclisation of alkynes leading to (E)-2-(2-arylvinyl)quinazolinones

Abstract

2-[N-Alkyl(benzyl)-N-(prop-2′-ynyl)]aminobenzamides 5 reacted with aryl iodides 2 under palladium–copper catalysis to yield disubstituted alkynes 6–13, which underwent a novel cyclisation in the presence of CuI, K2CO3, n-Bu4NBr in acetonitrile to yield (E)-1-alkyl(benzyl)-3-aryl-2-(2-arylvinyl) quinazolin-4-ones 14–21 in excellent yields instead of the expected benzodiazepinones 22.