Radical and anionic response of N-(bromomethanesulfonyl)-substituted alpha,alpha '-bridged piperidine substrates

The N-(bromomethanesulfonyl) azabicyclic ketones 2a-c and their exo-methyle ne analogues 1a-c were prepared. Our examination of the radical-induced beh avior of the latter triad provided experimental evidence for the propensity of the b and c systems to engage in 7-endo cyclization. For 1a, only reduc tive debromination was observed. In no instance was ring closure by the B-e xo radical mode seen. As concerns ketones 2a-c, all three showed a remarkab le facility for engaging in intramolecular S(N)2 displacement in the presen ce of KHMDS. Yields at the mid-80% level were realized irrespective of the value of it. Molecular mechanics calculations of the Monte Carlo type were performed on several conformational isomers and product classes in an effor t to provide support for the explanatory conclusions offered as rationale-f or the collective experimental observations.