Synthesis of medium-sized benzo[b]azocines and benzo[b]azonines by photoinduced 8-/9-endo sulfonyl-cyclization

An efficient photochemical radical sulfonyl cyclization of designed dienes to medium-sized benzo[b]azocines and benzo[b] azonines was developed. This chemoselective method provides new highly functionalized eight- and nine-membered N-het-erocycles. Radical inhibition experiments, light on/off experiments, and apparent quantum efficiency calculations were used to clarify the radical mechanism. Density functional theory calculations enabled rationalization of the rate-determining step and observed chemoselectivity. Large-scale synthesis and derivatizations via epoxidation and convenient N-Ts deprotection showed the potential utility of this strategy. This photochemical method for synthesizing sulfonylbenzo[b]azocines and sulfonylbenzo[b] azonines with insertion of sulfur dioxide provides new sustainable routes for the synthesis of valuable medium-sized N-heterocycles.

Automated summary

An efficient photochemical radical sulfonyl cyclization method was developed for the synthesis of medium-sized benzo[b]azocines and benzo[b] azonines. This chemoselective method allows the synthesis of highly functionalized eight- and nine-membered N-heterocycles. Experimental studies and computational calculations were used to understand the radical mechanism and rationalize the observed chemoselectivity. The large-scale synthesis and derivatizations demonstrated the potential utility of this strategy for the synthesis of valuable medium-sized N-heterocycles.