Palladium-catalyzed coupling reactions for the preparation of concatenated azoles

Abstract

The coupling reactions mediated by sp 2 -sp 2 transition metals, mostly Pd, allowed the chemoselective preparation of some synthetic compounds and intermediate structures of great complexity. This work describes the methodology used to obtain several derivatives with bisoxazole and thiazole-oxazole units. The required organozinc reagents were prepared from n-BuLi and ZnCl 2, and the bimetallic derivative of ethyl oxazole-4-carboxylate was obtained by a second transmetalation with CuI.