A facile synthesis of [1,2,3]triazolo[1,5- <i>a</i> ]quinazolines <i>via</i> a copper-catalyzed tandem reaction and their denitrogenative transformation into 2-acyl-quinazolines

A one-pot reaction protocol of 2-bromobenzyl azides with substituted acetonitriles for highly effective synthesis of [1,2,3]triazolo[1,5-<i>a</i>]quinazolines was developed. The reaction process involved base-promoted [3 + 2] cyclization, Cu-catalyzed Ullmann coupling, oxidative aromatization, and Dimroth rearrangement sequences. Furthermore, the obtained [1,2,3]triazolo[1,5-<i>a</i>]quinazolines could transform into 2-acyl-quinazolines <i>via</i> a Cu-catalyzed denitrogenative ring-opening reaction under acidic conditions. The mechanism was investigated using additional DFT calculations, and the ring-opening and ring-closing (RORC) process of Dimroth rearrangement probably was driven by thermodynamic stability.