A new facet of amide synthesis by tandem acceptorless dehydrogenation of amines and oxygen transfer of DMSO

We have developed a new catalytic system for preparing amides by tandem acceptorless dehydrogenation of amines and oxygen transfer of DMSO. This system shows very good catalytic activity and selectivity, a variety of primary amines and even diamines are converted into the corresponding amides in good to quantitative yields (>99 %). The unprecedented catalytic performance of this binuclear ruthenium complex was attributed to a unique chelating model wherein one Ru center combines with N atom of RCHNH produced from the dehydrogenation of RCH2NH2 and the other co-ordinates with the S atom of DMSO, thus bringing the DMSO and imine molecules into proximate to enhance the efficiency of the oxygen transfer from DMSO via a six-membered ring transition state. The mechanism study indicated that the oxygen in the product amides came from DMSO and CH bond cleavage in DMSO was the rate determining step.