TRANSITION METAL-CATALYZED RADICAL CYCLIZATIONS - A LOW-TEMPERATURE PROCESS FOR THE CYCLIZATION OF N-PROTECTED N-ALLYLTRICHLOROACETAMIDES TO TRICHLORINATED GAMMA-LACTAMS AND APPLICATION TO THE STEREOSELECTIVE PREPARATION OF BETA,GAMMA-DISUBSTITUTED GAMMA-LACTAMS

Cyclizations of N-substituted N-allyltrichloroacetamides, where the substituent is an alkyl, Cbz, Boc, Ts, or Ms group, are catalyzed by a 1:1 mixture of CuCl and bipyridine to give the corresponding beta,gamma-trichlorinated gamma-lactams in high yields. The reactions proceed at temperatures from -78-degrees-C to room temperature. Cyclizations of N-allyltrichloroacetamides of acyclic secondary allylic amines are achieved with good selectivity; the cis/trans ratios of the gamma-lactams formed were dependent on the substituents on the nitrogen atom. The stereochemical outcome is compared with that of free-radical cyclization.