ENANTIOSELECTIVE RHODIUM(II) CATALYSTS

Dimeric rhodium(II) compounds of the type [Rh2(OAc)4] are valuable catalysts for carbene reactions, for example for the formation of cyclopropanes from olefins and diazo compounds. As yet no catalyst can compete with [Rh2((5S)‐mepy)4] (1, mepy is the methyl ester of the ()‐(S)‐pyrrolidinone‐5‐carboxylic acid deprotonated at the N atom), a new enantioselective catalyst for reactions such as the cyclopropenation of acetylenes with diazo compounds and for the formation of five‐membered rings in intramolecular CH insertions. (For two of the ligands in 1 only the ligating atoms are drawn.) (Figure Presented.) Copyright © 1992 by VCH Verlagsgesellschaft mbH, Germany