Organocatalytic Asymmetric Conjugate Addition of Aldehydes to Nitroolefins: Identification of Catalytic Intermediates and the Stereoselectivity‐Determining Step by ESI‐MS

Abstract

Looking back: The asymmetric organocatalytic 1,4-addition of aldehydes to nitroolefins was studied by ESI-MS. Analysis of the back reaction starting from quasienantiomeric mass-labeled 1,4-adducts (see scheme) provided conclusive evidence for an enamine rather than an enol mechanism, and allowed identification of the enantioselectivity-determining step.