An Oxidant-Free and Mild Strategy for Quinazolin-4(3 H )-One Synthesis via CuAAC/Ring Cleavage Reaction.

An oxidant-free and highly efficient synthesis of phenolic quinazolin-4(3 H )-ones was achieved by simply stirring a mixture of 2-aminobenzamides, sulfonyl azides, and terminal alkynes. The intermediate N -sulfonylketenimine underwent two nucleophilic additions and the sulfonyl group eliminated through the power of aromatization. The natural product 2-(4-hydroxybenzyl)quinazolin-4( 3H )-one can be synthesized on a large scale under mild conditions with this method.