Regioselective Formation of 2,5-Disubstituted Oxazoles Via Copper(I)-Catalyzed Cycloaddition of Acyl Azides and 1-Alkynes

Abstract

The reaction of 1-alkynes with acylazides in the presence of [Tpm*,BrCu(NCMe)]BF4 (Tpm*,Br = tris(3,5-dimethyl-4-bromopyrazolyl)methane) as the catalyst provides 2,5-oxazoles in moderate to high yields. This is a novel transformation of CuAAC type, that constitutes a significant variation of the commonly observed [3+2] cycloaddition reaction to yield 1,2,3-triazoles