Enantioselective SN1-type reaction via electrochemically generated chiral α-Imino carbocation intermediate

Abstract

Electrochemical reactions via carbocation intermediates remain fundamental transformations that build up molecular functionality and complexity in a sustainable manner. Enantioselective control of such processes is a great challenge in a highly ionic electrolyte solution. Here, we report an anodic generation of chiral α-imino carbocation intermediates by enamine catalysis. The chiral carbocation intermediates can be intercepted by a variety of nucleophiles such as alcohols, water and thiols with high stereoselectivity. The key SN1 step proceeds via a tertiary amine-mediated proton shuttle that facilitates facial selection in reacting with carbocation. Carbocations are useful synthetic intermediates which enable direct functionalization of carbon centers, but their generation in a manner that uses mild conditions and enables stereoselective interception remains a longstanding goal of organic chemists. Here, the authors use electrochemical enamine oxidation to synthesize chiral scaffolds from racemic α-branched aldehydes.