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Synfacts 2007(6): 0649-0649  
DOI: 10.1055/s-2007-968564
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Organocatalysis Using SOMO Activation

Contributor(s): Benjamin List, Subhas Chandra Pan
T. D. Beeson, A. Mastracchio, J.-B. Hong, K. Ashton, D. W. C. Macmillan*
Princeton University and California Institute of Technology, Pasadena, USA
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Publikationsdatum:
22. Mai 2007 (online)

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Significance

The authors report a direct enantio­selective allylic alkylation of aldehydes using SOMO activation. They recognized that a one-electron oxidation of a transient enamine species would generate a 3π-electron radical cation with a singly occupied molecular orbital (SOMO) that is activated to a variety of π-rich nucleophiles. Imidazolidinium salt 1 was found to be the best catalyst and ceric ammonium nitrate (CAN) was used as the stoichiometric oxidant for the allylic alkylation of different aldehydes. With 20 mol% of the catalyst 1 and two equivalents of CAN, good to high yields (72-88%) and high enantioselectivities (ee = 93:7 to 98:2) are obtained for a variety of allylsilanes.