Enantioselective (3+2)-Annulation of -Keto Esters with Azoalkenes towards Bicyclic Dihydropyrroles via Cooperative Palladium and Br?nsted Acid Catalysis

A cooperative catalytic process through palladium and Br & oslash;nsted acid activation is developed for the conjugate addition of cyclic beta-keto esters to azoalkenes directly followed by hemiaminal formation upon cyclization. This transformation is enabled by utilizing chiral Pd-aqua complexes as combined Br & oslash;nsted acid-base catalysts. Thus, bicyclic and highly functionalized dihydropyrroles with two contiguous quaternary stereogenic centers are formed in excellent yields as single diastereomers and with exceptional enantioselectivity