Enantioselective photoredox catalysis enabled by proton-coupled electron transfer: development of an asymmetric aza-pinacol cyclization.
作者： Lydia J. Rono , Hatice G. Yayla , David Y. Wang , Michael F. Armstrong , Robert R. Knowles
DOI: 10.1021/JA4100595
关键词:
摘要: The first highly enantioselective catalytic protocol for the reductive coupling of ketones and hydrazones is reported. These reactions proceed through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer (PCET) event jointly mediated by chiral phosphoric acid catalyst photoredox Ir(ppy)2(dtbpy)PF6. Remarkably, these radicals appear to remain H-bonded conjugate base Bronsted during course subsequent C–C bond-forming step, furnishing syn 1,2-amino alcohol derivatives with excellent levels diastereo- enantioselectivity. This work provides demonstration feasibility potential benefits PCET activation in asymmetric catalysis.
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