MgI₂-Accelerated Enantioselective ;Morita-Baylis-Hillman Reactions

Significance

The Morita-Baylis-Hillman reaction is an atom-economical method of rapid increase of molecular complexity. The development of asymmetric modifications of this process has received considerable attention in recent years. In this paper the authors developed a highly enantio-selective system based on Fu’s planar chiral DMAP derivative 1. It was shown that the applicability of the reaction can be expanded by the use of a simple Lewis acid co-catalyst (50 mol% MgI₂). The protocol appeared to be most efficient for ­aromatic aldehydes. Enantioselectivities of up to 98% ee were obtained accompanied by good to excellent yields. Aliphatic substrates demonstrated inferior results.