Enantioselective radical cyclizations: A new approach to stereocontrol of cascade reactions

Abstract

Stereocontrol in a cascade radical additioncyclization-trapping reaction was achieved by a new approach, which utilizes a hydroxamate ester moiety as a coordinating chiral Lewis acid tether between two radical acceptors. A remarkable feature of this reaction is the construction of three bonds and tertiary and quaternary stereogenic centers through both inter- and intramolecular carbon-carbon bond-forming processes. The chiral Lewis acid mediated reaction of oxime ethers also proceeded smoothly with good enantio- and diastereoselectivities, indicating the usefulness of the cascade approach for the asymmetric synthesis of various y-lactams. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.