Comparative enantiocontrol with allyl phenyldiazoacetates in asymmetric catalytic intramolecular cyclopropanation.

Dirhodium(II) azetidinone-carboxylates are effective asymmetric catalysts for diazo decomposition of allyl diazoacetates and their subsequent intramolecular cyclopropanations. The effect of alkene substituents on enantiocontrol has been examined and modest selectivities have been achieved. Steric influences from substituents on the diazo carbon are seen to diminish enantioselectivities. Copyright 2003 Wiley-Liss, Inc.