Cu(I)-catalysed cross-coupling reaction of in situ generated azomethine ylides towards easy construction of fused N-heterocycles.

In this study, we have devised a new method for synthesizing highly valuable 5,6,7,8 a -tetrahydropyrrolo[2,1- b ]thiazoles using a decarboxylative C-N coupling reaction between phenyl glyoxal and proline or its analogue, which is catalyzed by CuI in the presence of K 2 CO 3 . This reaction is followed by a regiospecific C-C and C-S coupling cyclization with dialkyl trithiocarbonate. Furthermore, we have demonstrated that this cross-coupling method can also be extended to imines, leading to the formation of fused symmetrical and unsymmetrical 6,7-dihydro-5 H -pyrrolo[1,2- a ]imidazoles. This finding greatly expands the scope and versatility of the synthetic approach. Therefore, this work represents a significant contribution to the field of organic synthesis, providing a novel and efficient method for the preparation of fused N-heterocyclic compounds that could have useful applications in areas such as material science and pharmaceuticals.