Reactions of a,ß‐unsaturated N‐benzenesulfonyl Imine – N‐[(2E)‐3‐phenyl‐2‐propen‐1‐ylidene]benzenesulfonamide with Methyllithium

alpha,beta-Unsaturated N-benzenesulfonyl imine 1 was treated with 1.1 eq methyllithium to afford 1,2-addition adduct as a sole product. However, when compound 1 was treated with 2 eq MeLi, 1,2-addition product, benzenesulfonamide derivative 3 and 2H-1,2-benzothiazine 1,1-dioxide derivatives 4 and 5 were isolated.