Free radical cyclization reactions of allylsulfonyl substituted N-aryl amide derivatives

p-Toluenesulfonyl radical can be generated by the manganese(III) acetate oxidation of sodium p-toluenesulfinate. The corresponding alkyl radicals could be produced effectively by the p-toluenesulfonyl radical induced radical reaction of allylsulfonyl substituted N-aryl amides. These alkyl radicals undergo 5-exo-trig, 6-endo-trig, or 6-exo-trig cyclization onto the aromatic ring effectively. The product distribution is highly dependent on the substituent of aromatic ring and the stability of radical intermediate. This p-toluenesulfonyl radical induced reaction provides a synthetically useful method for the synthesis of dihydroquinolinones, azaspirocyclic cyclohexadienes, and spirodihydroquinolinones.