Expeditious synthesis of 3,4-dihydro-2H-1 lambda(6)-benzo[e][1,2]thiazine 1,1-dioxides

A novel pathway for the preparation of 3,4-dihydro-2H-1 lambda(6)-benzo[e][ 1,2]thiazine 1,1-dioxides 3 via an ortho-methyl lithiation/cyclization reac tion of N-acyl-o-toluenesulfonamides 5 is reported, Readily available N-acy l-o-toluenesulfonamides 5 were treated with 2 eq of n-BuLi at -78 degrees C -0 degrees C to give the corresponding sultams 6 in moderate to good yields . The resulting sultams 6 were converted to saturated sultams 3, which can be considered as one carbon-extended homologues of the Oppolzer sultams 1, in high yields by hydrogenation, Studies on the scope and limitation of thi s annulation for the preparation of sultams are discussed, Demonstration of the feasibility of using the sultams 3 templates for an electorophilic flu orinating agent is also described.