| Title: | "Iridium-catalyzed asymmetric hydrogenation of unfunctionalized, trialkyl-substituted olefins" |
| Author(s): | Wang A; Fraga RP; Hormann E; Pfaltz A; |
| Address: | "Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland" |
| ISSN/ISBN: | 1861-471X (Electronic) 1861-471X (Linking) |
| Abstract: | "Chiral iridium complexes with bicyclic pyridine-based N,P ligands have emerged as efficient catalysts for the enantioselective hydrogenation of unfunctionalized trialkyl-substituted olefins. Optimization of the reaction conditions by variation of the solvent, pressure, and temperature led to enantiomeric excesses of up to 99%. Three pure alkenes, (E)-2-cyclohexyl-2-butene and (E)- and (Z)-3,4-dimethyl-2-pentene were converted into the corresponding chiral alkanes with 97%, 94%, and 93% ee, respectively. Hydrogenation of the three C=C bonds of both alpha- and gamma-tocotrienyl acetate led to alpha- and gamma-tocopheryl acetate with very high diastereoselectivity. The same catalysts were successfully applied in the hydrogenation of trisubstituted alkenes with a carboxylic ester or a keto group in the gamma position. This reaction was used as a key step in a highly enantioselective synthesis of the pheromone of the caddisfly Hesperophylax occidentalis. The hydrogenation of a structurally analogous allylic alcohol also gave high enantioselectivities" |
| Keywords: | Alkenes/*chemistry Catalysis Hydrogenation Iridium/*chemistry; |
| Notes: | "MedlineWang, Aie Fraga, Rui P A Hormann, Esther Pfaltz, Andreas eng Research Support, Non-U.S. Gov't Germany 2010/10/23 Chem Asian J. 2011 Feb 1; 6(2):599-606. doi: 10.1002/asia.201000595. Epub 2010 Oct 21" |
