Ruthenium(I)-catalyzed cyclopropanation reactions with (trimethylsilyl)diazomethane and aryldiazomethanes

The polymeric ruthenium(I) complex [Ru2(CO)4(μ-OAc)2]n is a suitable catalyst for the cyclopropanation of mono-, 1,1- as well as 1,2-disubstituted, and trisubstituted alkenes with (trimethylsilyl)diazomethane, phenyl-diazomethane, and (4-cyanophenyl)diazomethane. Trisubstituted alkenes are cyclopropanated with a remarkable degree of syn-selectivity.