Organocatalyzed Transient Dienamine-Mediated Diels-Alder Reactions between α,β-Unsaturated Ketones and Alkenes

Organocatalyzed (4+2) cycloadditions (Diels-Alder reactions) are reviewed in this manuscript. Among the different catalytic alternatives, reactions involving α,β-unsaturated ketones and alkenes are considered. In these processes, substituted cyclohexanones are obtained via HOMO activation generated by amine organocatalysis that generate transient dienamine species. Both concerted and stepwise mechanisms are described. In most cases, excellent regio-, diastereo- and enantiocontrol have been observed.