Highly enantioselective hydrogenation of N-phthaloyl enamides

Rh- or Ru-catalyzed highly enantioselective hydrogenation of N-phthaloyl enamides is presented. Electron-rich Tang-Phos and DuanPhos are found to be effective ligands for Rh-catalyzed hydrogenation of alpha-aryl enamides and up to 99% ee has been achieved. In contrast, for the hydrogenation of alpha-alkyl enamide.. the Ru-C-3-TunePhos complex is more effective and up to 69% ee can be observed. This work is the first report of the hydrogenation of N-phthaloyl enamides. (c) 2005 Elsevier Ltd. All rights reserved.