Catalytic asymmetric conjugate addition of indolizines to unsaturated ketones catalyzed by chiral-at-metal complexes

Abstract

A highly enantioselective conjugate addition of indolizine and its analogues with α,β-unsaturated 2-acyl imidazoles has been developed. In the presence of 1.0 mol% of Δ-Rh1, the corresponding adducts were obtained in good yields (85–98%) with excellent enantioselectivities (95%–>99%) to resolve the difficult issue faced with organocatalysts which could not control well the stereoselectivity of the reaction due to monofunctional activation. Remarkably, this protocol exhibits extraordinary advantages in terms of reactivity and enantioselectivity, given the fact that as low as 0.05 mol% of Δ-Rh1 can promote the title reaction on gram scale to afford the desired product with excellent enantioselectivity.