Initiating radical cyclizations by Hradical dot 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 Hradical dot 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.