Ni-Catalyzed Synthesis of Methylenebisamides: Dual Role of DMSO Both as Methylene Source and Oxidant

A simple and efficient procedure for the synthesis of methylenebisamides using a nickel-catalyzed C−S bond cleavage of DMSO was achieved. Remarkable results obtained from mechanistic experiments clearly show that DMSO plays a dual role in this transformation; both as an economical and environmentally benign one-carbon synthon and an oxidizing agent. Also, based on these mechanistic studies, a mechanism was proposed for the formation of methylenebisamide. Both (hetero)aromatic and pseudo-aromatic nitriles and amides can be employed for the synthesis of methylenebisamides. The results of robustness screen analyses further showed that the procedure is of high tolerance to different chemical functionalities and chemical motifs. The optimized conditions are scalable with very good to excellent yields and the process is atom-economic. Moreover, purified products were obtained in good to excellent yields through a facile crystallization procedure.