REVERSE COPE ELIMINATION-REACTIONS .1. MECHANISM AND SCOPE(L-3)

N-4-Pentenyl- and N-5-hexenyl-N-methylhydroxylamine cyclized under mil d conditions in a reverse Cope elimination reaction to give 1,2-dimeth ylpyrrolidine N-oxide and 1,2-dimethylpiperidine N-oxide, respectively . The reaction was shown to be concerted and thermodynamically control led. The scope of this novel cyclization is discussed, and comparisons are made with the closely related and previously reported cyclization of monosubstituted alkenylhydroxylamines to give cyclic hydroxylamine s.