A New Approach to Diastereoselective and Enantioselective Cyclopropane Syntheses Using the Chiral Iron Carbene Complexes S- and R-[(η5-C5H5)(CO)2FeCH[(η6-o-CH3OC6H4)Cr(CO)3]]+

Different methods for the synthesis of iron carbene complexes or their precursors have been summarized. New diastereomerically pure carbene precursors RR-(+)- and SS-(−)-(η5-C5H5)(CO)2FeCH(OSiMe3)[η6-o-CH3OC6H4Cr(CO)3] have been prepared by the reaction of the Fp anion with enantiomerically pure S-(+) or R-(−)-o-anisaldehyde(tricarbonyl)chromium complexes. They were then converted to the corresponding iron carbene complexes S- and R-[(η5-C5H5)(CO)2FeCH[(η6-o-CH3OC6H4)Cr(CO)3]]+. Enantioselective carbene transfers from these complexes to 2-methylpropene, 1,1-diphenylethylene, styrene, p-methylstyrene, p-chlorostyrene, and p-trifluoromethylstyrene gave o-methoxyphenylcyclopropanes with high diastereoselectivities and moderate to excellent enantioselectivities.