Direct Asymmetric α-Allylation of α-Branched Aldehydes by Two Catalytic Systems with an Achiral Pd Complex and a Chiral Primary α-Amino Acid

Direct alpha-allylation of alpha-branched aldehydes was successfully carried out with a readily available allyl ester by combined use of two catalytic systems: Tsuji-Trost allylation reaction with an achiral palladium complex and enamine catalysis with a chiral primary alpha-amino acid. A quaternary carbon stereogenic center was constructed stereoselectively to give various 2,2-disubstituted pent-4-enals in good yields with high enantioselectivity.