Organocatalytic Transfer Hydrogenation of Cyclic Enones

• Published in: Journal of the American Chemical Society Vol. 128; no. 39; pp. 12662 - 12663
• Main Authors: Tuttle, Jamison B, Ouellet, Stéphane G, MacMillan, David W. C
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 04.10.2006; Amer Chemical Soc
• Subjects: Catalysis; Chemistry; Chemistry, Multidisciplinary; Cycloparaffins - chemistry; Exact sciences and technology; General and physical chemistry; Hydrocarbons, Cyclic - chemical synthesis; Hydrocarbons, Cyclic - chemistry; Hydrogen - chemistry; Ketones - chemical synthesis; Ketones - chemistry; Models, Molecular; Molecular Conformation; Oxidation-Reduction; Physical Sciences; Science & Technology; Stereoisomerism; CATALYSIS; ION; AMINE; NICOTINAMIDE; TRANSITION STRUCTURES; HYDRIDE TRANSFER; Catalytic reaction; Cyclic compound; Enone; Hydrogenation
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0653066

The first enantioselective organocatalytic transfer hydrogenation of cyclic enones has been accomplished. The use of iminium catalysis has provided a new organocatalytic strategy for the enantioselective reduction of β,β-substituted α,β-unsaturated cycloalkenones, to generate β-stereogenic cyclic ketones. The use of imidazolidinone 4 as the asymmetric catalyst has been found to mediate the hydrogenation of a large class of enone substrates with tert-butyl Hantzsch ester serving as an inexpensive source of hydrogen. The capacity of catalyst 4 to enable enantioselective transfer hydrogenation of cycloalkenones has been extended to five-, six-, and seven-membered ring systems. The sense of asymmetric induction is in complete accord with the stereochemical model first reported in conjunction with the use of catalyst 4 for enantioselective ketone Diels−Alder reactions.