A new approach to diastereoselective and enantioselective cyclopropane syntheses using the chiral iron carbene complexes S- and R-[(eta(5)-C5H5)(CO)(2)Fe=CH[(eta(6)-o-CH3OC6H4)Cr(CO)(3)]](+)

Different methods for the synthesis of iron carbene complexes or their prec ursors have been summarized; New diastereomerically pure carbene precursors RR-(+)- and SS-(-)-(eta(5)-C5H5)(CO)(2)FeCH(OSiMe3)[eta(6)-o-CH3OC6H4Cr(CO )(3)] have been prepared by the reaction of the Fp anion with enantiomerica lly pure S-(+) or R-(-)-o-anisaldehyde(tricarbonyl)chromium complexes. They were then converted to the corresponding iron carbene complexes S- and R-[ (eta(5)-C5H5)(CO)(2)Fe=CH[(eta(6)-o-CH3OC6H4)Cr(CO)(3)]](+). Enantioselecti ve carbene transfers from these complexes to 2-methylpropene, 1,1-diphenyle thylene, styrene, p-methylstyrene, p-chlorostyrene, and p-trifluoromethylst yrene gave o-methoxyphenylcyclopropanes with high diastereoselectivities an d moderate to excellent enantioselectivities. (C) 2000 Published by Elsevie r Science Ltd.