Morita-Baylis-Hillman Reaction. A Caveat

It is an oversight to consider that a Lewis base such as a trialkylamine adds to an activated alkene in conjugate fashion to generate an enolate as a 1,5-zwitterion, which next reacts in aldol fashion with an electrophile such as an aldehyde to move on further through other events to the Morita-Baylis-Hillman product. It is demonstrated from computational investigations that the union of trialkylamine and activated alkene leads possibly to a very low level charge-transfer entity, wherein the p-electron density of the alkene has little perturbed to call it an enolate in the conventional sense. It is suggested to consider the aldol reaction as the first step of the Morita-Baylis-Hillman reaction and arrive at the corresponding transition state structure directly from the three entities.