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DOI: 10.1055/s-2008-1042723
Organocatalytic Tandem Oxidative Dearomatization-Michael Reaction
Contributor(s):Benjamin List, Subhas Chandra PanUniversity of Cambridge, UK
An Enantioselective Organocatalytic Oxidative Dearomatization Strategy
J. Am. Chem. Soc. 2008, 130: 404-405
Publication History
Publication Date:
21 February 2008 (online)
Key words
oxidative dearomatization - Michael reaction - phenols - enantioselectivity
Significance
The authors report an enantioselective organocatalytic tandem oxidative dearomatization-Michael reaction. Diacetoxyiodobenzene was used as oxidant and catalyst 1 was found to be the best catalyst for the desymmetrizing Michael reaction. The authors found that methanol can act both as nucleophile and as solvent for this tandem operation. With 10 mol% of catalyst 1, good to high diastereoselectivities (dr = 6.7:1 to >20:1 dr) and excellent enantioselectivities (er = 98:2 to >99:1) are obtained for different phenols. Lower enantioselectivity (er = 70:30) was obtained when a substituted 2,6-dimethyl phenol was used.
Comment
Hayashi and co-workers have recently reported secondary amine catalyzed desymmetrizing Michael reactions of different meso-cyclohexadienones (J. Am. Chem. Soc. 2005, 127, 16028). The present authors have elegantly combined the processes namely phenol oxidation and Michael reaction in one pot. The authors have also shown that non-oxygenated nucleophiles could give high enantioselectivity in this reaction.