Enantioselective Mukaiyama–Michael Reaction of β,γ-Unsaturated α-Keto Esters with Silyl Ketene Acetals Catalyzed by a Chiral Magnesium Phosphate

Abstract

We would like to describe an efficient and highly enantioselective Mukaiyama–Michael reaction of silyl ketene acetals with β,γ-unsaturated α-keto esters catalyzed by a chiral magnesium BINOL-derived phosphate. The resulting functionalized 1,5-dicarbonyl adducts are obtained in high yields (up to 96%) and with excellent enantioselectivities (up to 98%) under mild conditions. Two plausible mechanistic pathways were proposed, including a 1,4-addition and a hetero Diels–Alder [4 + 2] cycloaddition.

Magnesium-Catalyzed Regioselective Hydrophosphinylation of Alkenes with Diarylphosphine Oxides

“…Magnesium is a redox-inactive alkaline earth metal and has been remarkably applied to stoichiometric reactions in the form of Grignard reagents for more than a century. Due to its low cost and environmentally benign nature, magnesium as catalytic reagents has also witnessed remarkable advances in hydroboration of unsaturated bonds, alkene hydroamination/hydrogenation, dehydrocoupling reactions, and others . Compared with these well-established transformations, the magnesium catalysis toward alkene hydrophosphinylation remains largely lagged behind.…”