Asymmetric Catalytic Aza-morita-baylis-hillman Reaction (aza-mbh): An Interesting Functional Group-caused Reversal Of Asymmetric Induction

摘要

A highly efficient aza-Morita-Baylis-Hillman reaction (aza-MBH reaction) of N-tosyl salicylaldehyde imines with α,β-unsaturated ketones has been achieved by using β-isocupreidine (β-ICPD) as the catalyst (10 mol%) to give the corresponding adducts in good to high yields (90%-quant.) and excellent ee's (up to 99% ee), with adducts showing the opposite absolute configuration to that of those obtained in the similar aza-MBH reaction of N-tosyl aldimines with α,β-unsaturated ketones.rnAsymmetric catalysis by the use of bifunctional organo-catalysts via hydrogen bonding has become one of the most active research areas in the past decade. A synergistic activation by the functionalities on the catalyst can lead to specific control of the transition state and result in chiral products with high enantioselectivity. Recently, the aza-Morita-Baylis-Hillman (aza-MBH) reaction of N-sulfonated imines (ArCH = NTs) with various Michael acceptors such as methyl vinyl ketone (MVK) has received much attention. We and others have successfully developed several excellent catalytic systems by using chiral nitrogen and phosphine Lewis bases as multifunctional organocatalysts and have achieved high enantioselectivities for this reaction.