Synthesis of 3,4-Dihydro-2<i>H</i>-1,3,5-thiadiazines

3,4-Dihydro-2<i>H</i>-1,3,5-thiadiazines substituted at the 3 and 6 positions were synthesized by treatment of N<i>-</i>substituted <i>N,N</i>-bis(1<i>H</i>-1,2,3-benzotriazol-1-ylmethyl)-amines with thioamides and zinc bromide in dry CH<sub>2</sub>Cl<sub>2</sub> at room temperature for 48−60 h in 48−80% yields.