Catalytic Asymmetric Roskamp Reaction of α-Alkyl-α-diazoesters with Aromatic Aldehydes: Highly Enantioselective Synthesis of α-Alkyl-β-keto Esters.

The first catalytic enantioselective Roskamp reaction of α-alkyl-α-diazoesters with aromatic aldehydes was realized using a simple chiral N,N′-dioxide−scandium(III) complex. Remarkably, with 0.05 mol % catalyst, the reaction was performed well over a series of substrates, giving the desired products chemoselectively in excellent yields (up to 99%) and enantioselectivities (up to 98% ee) under mild conditions. This protocol provides a promising method for the synthesis of chiral α-alkyl-β-keto esters and 1,3-diols.