Organocatalytic Asymmetric Mannich Reaction of Malonates with Imines

Significance

Here the authors report a highly enantioselective Mannich reaction of N-Boc imines with malonates and β-keto esters. Bifunctional cinchona alkaloid based catalyst 1 bearing a 6′-thiourea functionality was found to be effective for the reaction. In the presence of 20 mol% of the catalyst, good yields (81-99%) and high enantio­selectivities (96-99%) are obtained for different aryl imines. One equivalent of the catalyst was required in order to obtain high enantioselectivities with alkyl imines.