An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.