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Synfacts 2007(8): 0877-0877
DOI: 10.1055/s-2007-968749
DOI: 10.1055/s-2007-968749
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York
Enantioselective α-Enolation of Aldehydes by SOMO Activation
H.-Y. Jang, J.-B. Hong, D. W. C. MacMillan
Princeton University and California Institute of Technology, Pasadena, USA
Further Information
Publication History
Publication Date:
24 July 2007 (online)
Significance
An organocatalytic enantioselective α-enolation of aldehydes using SOMO activation has been developed. The combination of imidazolidinone catalyst 1, ceric ammonium nitrate (CAN; 2 equiv), water (2 equiv) and 2,6 di-tert-butyl pyridine (DTBP; 2 equiv) has been identified as efficient conditions for the reaction. The SOMO-activated radical cation 6 reacts with the silyl enol ether 3 to generate α-siloxy radical 7, which is further oxidized with CAN to cation 8, and finally product 4 is formed by removal of the silyl group. With 20 mol% of catalyst 1 moderate to high yields (55-92%) and excellent enantioselectivities (er = 93:7 to 98:2) have been obtained for different aldehydes and enolsilanes.