Substituent-Controlled Regioselective Photoinduced Cyclization of N -Allylbenzamides with N -Sulfonylaminopyridinium Salts.

The annulation reactions of N -allylbenzamides with N -sulfonylaminopyridinium salts were developed under metal-free photoinduced mild conditions. Substituent-controlled sulfonaminoarylation and sulfonaminooxylation of benzamides were realized: N -allylbenzamides lead to benzosultams, while N -(2-phenylallyl)benzamides give sulfonamidylated oxazoline derivatives. Control experiments indicated that those reactions undergo a radical pathway with arylsulfonamidyl radicals as the intermediates. The aryl C-H bond functionalization in arylsulfonamidyl was involved for the first time to give benzosultams.