Until now, only one method for the synthesis of 1,2,4,5-tetrahydro-3,2-benzothiazepine 3,3-dioxides is known. These compounds were obtained by sulfonylamidomethylation of 2-phenylethanesulfonamides 1 with formaldehyde in the presence of an acid catalyst followed by intramolecular cyclization of the imine intermediate by means of electrophilic aromatic substitution. [ 4 4. Zinczuk , J. ; Sorokin , IH ; Orazi , OO ; Corral , RA Intramolecular sulphonamidomethylation: Fused ...