Abstract (η 5-C 5 H 5)(CO) 2 FeCH (CH 3) SPh (8) serves as a quite useful reagent for the transfer of ethylidene groups to alkenes to give methyl-substituted cyclopropanes in good yields. The reaction is accomplished by allowing 8 to react with an alkylating agent such as trimethyloxonium tetrafluoroborate or methyl fluorosulfonate in the presence of the alkene substrate. The active ethylidene transfer reagent is apparently a sulfonium salt which is ...
