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DOI: 10.1055/s-2008-1072680
Enantioselective Reduction of N-Arylketimines with S-Chiral Catalysts
D. Pei, Y. Zhang, S. Wei, M. Wang, J. Sun*
Chengdu Institute of Biology and Graduate School of Chinese Academy of Sciences, Beijing, P. R. of China
Publication History
Publication Date:
23 April 2008 (online)
Significance
Recently the authors reported on the use of S-chiral sulfinamides in the enantioselective reduction of ketimines (Org. Lett. 2006, 8, 5913). Based on their observations a variety of second-generation catalysts for this transformation, consisting of two S-chiral sulfinamide groups connected by tethers of different lengths, were designed. With these new catalysts the reduction of different substituted N-arylketimines with trichlorosilane proceeds in good yields and enantioselectivities. The best catalyst was found to be the simple and highly flexible bissulfinamide 1. The use of several basic additives had only little beneficial effect on the enantioselectivities but lowered the reactivity in most cases. Only the use of 2,6-lutidine (30 mol%) increased the stereoselectivity without decreasing the yield.