Enantioselective Photoredox Catalysis Enabled by Proton-Coupled Electron Transfer: Development of an Asymmetric Aza-Pinacol Cyclization
Lydia J. Rono, Hatice G. Yayla, David Y. Wang, Michael F. Armstrong and Robert R. Knowles*
*Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States, Email: rknowlesprinceton.edu
L. J. Rono, H. G. Yayla, D. Y. Wang, M. F. Armstrong, R. R. Knowles, J. Am. Chem. Soc., 2013, 135, 17735-17738.
DOI: 10.1021/ja4100595 (free Supporting Information)
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A highly enantioselective catalytic protocol for the intramolecular reductive coupling of ketones and hydrazones furnishes cyclic syn 1,2-amino alcohol derivatives with excellent levels of diastereo- and enantioselectivity. The reaction proceeds through neutral ketyl radical intermediates generated via a concerted proton-coupled electron transfer event jointly mediated by a chiral phosphoric acid catalyst and a photoredox catalyst.
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