Organocatalytic transfer hydrogenation of cyclic enones

J Am Chem Soc. 2006 Oct 4;128(39):12662-3. doi: 10.1021/ja0653066.

Abstract

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 beta,beta-substituted alpha,beta-unsaturated cycloalkenones, to generate beta-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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Cycloparaffins / chemistry*
  • Hydrocarbons, Cyclic / chemical synthesis*
  • Hydrocarbons, Cyclic / chemistry*
  • Hydrogen / chemistry
  • Ketones / chemical synthesis*
  • Ketones / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Oxidation-Reduction
  • Stereoisomerism

Substances

  • Cycloparaffins
  • Hydrocarbons, Cyclic
  • Ketones
  • Hydrogen