Title: Enantioselective Organocatalytic Michael Addition of Aliphatic Ketones to Nitrodienes
Abstract: Abstract A highly enantioselective Michael addition of aliphatic ketones to nitrodienes has been achieved that is catalyzed by readily available chiral thioureas derived from (1R,2R)-diphenylethane-1,2-diamine. Treatment of ketones with nitrodienes in the presence of 10 mol% thiourea 1a and 10 mol% benzoic acid in toluene provided the desired Michael adducts with excellent enantioselectivities (up to 99% ee) and modest to excellent yields (up to 97%). Keywords: Enantioselective organocatalysisketonenitrodienenitro-Michael reactionprimary amine-thiourea ACKNOWLEDGMENTS We thank the National Natural Science Foundation of China (20772029) and the New Century Excellent Talents in University (NCET-07-0286) for financial support. Notes a Isolated yield after silica-gel column chromatography. b Determined by chiral HPLC analysis (Chiralpak AS-H column, hexane/i-PrOH 95:5). a Isolated yield after silica-gel column chromatography. b Determined by chiral HPLC analysis (Chiralpak AS-H column, hexane/i-PrOH 95:5). a The diastereomer ratio was determined by 1H NMR spectroscopy. b Isolated yield after silica-gel column chromatography. c Ee values of the major diastereomer, which were determined by chiral HPLC analysis using Chiralpak AD-H, Chiralpak AS-H, or Chiralcel OD-H columns. d Not determined.
Publication Year: 2011
Publication Date: 2011-11-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 7
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