Abstract
Catalytic enantioselective methods for the generation of cyclopropanes has been of longstanding pharmaceutical interest. Chiral dirhodium(II) catalysts prove to be an effective means for the generation of diverse cyclopropane libraries. Rh(2)(R-DOSP)(4) is generaally the most effective catalyst for asymmetric intermolecular cyclopropanation of methyl aryldiazoacetates with styrene. Rh(2)(S-PTAD)(4) provides high levels of enantioinduction with ortho-substituted aryldiazoacetates. The less-established Rh(2)(R-BNP)(4) plays a complementary role to Rh(2)(R-DOSP)(4) and Rh(2)(S-PTAD)(4) in catalyzing highly enantioselective cyclopropanation of 3- methoxy-substituted aryldiazoacetates. Substitution on the styrene has only moderate influence on the asymmetric induction of the cyclopropanation.