The cross-coupling reaction of organoalane reagents with 2-methylthiobenzo[d]thiazoles via C–S bond cleavage catalyzed by nickel

Abstract

A highly efficient and simple route for the synthesis of 2-substituted benzo[d]thiazoles has been developed by nickel catalyzed cross-coupling of 2-methylthiobenzo[d]thiazoles with aryl and alkenylaluminum reagents. Various 2-(hetero)aryl and 2-alkenyl substituted benzo[d]thiazoles derivatives can be obtained with 31–94% isolated yields using 4 mol% NiCl₂(dppf)/4 mol% 2,2′-bipyridine as the catalyst under mild reaction conditions. The coupling reaction can be carried out smoothly whether the electron donor group or electron withdrawing group is on the aromatic ring of organic aluminum reagents or 2-methylthiobenzo[d]thiazoles derivatives. Furthermore, the broad substrate scope and the typical maintenance of vigorous efficiency on a gram scale make this protocol a potentially practical method to synthesize 2-substituted benzo[d]thiazoles derivatives. On the basis of the experimental results, a possible catalytic cycle has been proposed.