Rh-catalyzed intermolecular cyclopropanation with alpha-alkyl-alpha-diazoesters: catalyst-dependent chemo- and diastereoselectivity.Org Lett. 2008 Jul 17; 10(14):2987-9.OL
A Rh-catalyzed procedure for the cyclopropanation of alkenes with alpha-alkyl-alpha-diazoesters is described. With dirhodium tetraoctanoate, the predominant pathway is beta-hydride elimination. While a number of sterically demanding carboxylate ligands serve to avoid beta-hydride elimination, it was found that triphenylacetate (TPA) also imparts high diastereoselectivity.