Amine-promoted asymmetric [4+2] cycloadditions of α-acetoxymethyl allenoate and dual activated alkenes: stereoselective synthesis of poly-substituted cyclohexenes

Abstract A chiral secondary amine-promoted asymmetric [4+2] cycloadditions of α-acetoxymethyl allenoate 1 and electron-deficient alkenes 2 have been developed. The reaction features the utilization of addition–elimination reaction between allenoate 1 and the secondary amine to generate the key 2-aminobutadiene intermediate, which subsequently undergoes [4+2] cycloaddition with alkenes in a stepwise fashion, delivering the substituted cyclohexenes with good stereoselectivity.