The copper(I) complex (FcNN)Cu(OTf) (1; FcNN=N,N′-ethylenebis[(ferrocenylmethylene)amine] catalyzes reactions of ethyl diazoacetate with alkenes to form cyclopropanes in high yield. The same complex also catalyzes nitrene transfer from PhI=NTs to alkenes to produce aziridines in high yield.