Initiating radical cyclizations by H transfer from transition metals

CpCr(CO)3H and HV(CO)4(P-P) (where P-P is a chelating diphosphine) can be used to initiate radical cyclizations by transferring H to activated terminal olefins. CpCr(CO)3H can catalyze reductive cyclizations, with H2 as the ultimate reductant. Appropriate substrates can be assembled by the Morita-Baylis-Hillman reaction of methyl acrylate with an aldehyde. Six- as well as five-membered rings can be formed, and a tandem cyclization to decalin can be effected.