Novel heterocycles derived from substituted aroylthioureas: Synthesis of 3, l‐benzothiazin‐4‐ones, thieno[3,2‐ d ][1,3]thiazin‐4‐ones and 1,2,4‐thiadiazolo[2,3‐ a ][3,1]benzothiazin‐5‐ones

A series of heterocyclic aroylthioureas has been prepared and investigated as starting materials for ring closure reactions. The formation of several new 3,1‐benzothiazin‐4‐ones and thieno[3,2‐ d ][1,3]thiazin‐4‐ones ( via cyclocondensation reactions) is reported. Oxidative cyclizations were carried out to produce methyl benzothiazole‐4‐carboxylates ( via formation of an S‐C bond) as well as 1,2,4‐thiadiazolo‐[2,3‐ a ][3,1]benzothiazin‐5‐ones ( via formation of an SN bond).