We report the first highly enantioselective catalytic transformation for reductive coupling of ketones and hydrazones. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by a chiral phosphoric acid catalyst and the photoredox catalyst Ir(ppy)2(dtbpy)PF6. Remarkably, these neutral Ketyl radicals appear to remain hydrogen -bonded to the chiral conjugate base of the acid during the course of a subsequent C-C bond forming step, furnishing syn 1,2-amino alcohol derivatives with excellent levels of diastereo- and enantioselectivity. This work demostrates the feasibility and potential benefits of concerted PCET activation in asymmetric catalysis.

Enantioselective photoredox catalysis enabled by proton coupled electron transfer: Development of an asymmetric aza-pinacol cyclization

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.