Reaction of N-arylcarbamoyl-1,4-benzoquinone imines with sodium arenesulfinates

N-Arylcarbamoyl-1,4-benzoquinone imines possessing at least one free ortho position with respect to the carbonyl carbon atom in the quinoid ring react with sodium arenesulfinates according to the nucleophilic 1,4-addition pattern with complete regioselectivity. If both ortho positions are occupied, the reaction gives a mixture of products where the major ones are 1,6- and 6,1-adducts formed according to the radical ion mechanism.