Synthesis of 4-Alkyl-4-alkoxybutenolides Having Unsaturated Side Chains via Chromium Carbene Complex Photochemistry: (+)-Cerulenin.
The photochemical reaction between optically active ene carbamates and chromium alkoxycarbene complexes containing unsaturated aliphatic side chains was further developed. Although remote olefinic groups, including conjugated dienes, were tolerated, a homoallylic side chain underwent intramolecular reaction to give a strained cyclobutanone. (+)-Cerulenin was synthesized utilizing the photochemical reaction of an alkynylcarbene complex with an optically active ene carbamate and the bis(pi-crotyl)nickel halide alkylation of a vinyl bromide as key steps.
Kedar
Tracey E.
TE
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523.
Miller
Michael W.
MW
Hegedus
Louis S.
LS