Synthesis of 3,4-Dihydro-2H-1,3,5-thiadiazines

3,4-Dihydro-2H-1,3,5-thiadiazines substituted at the 3 and 6 positions were synthesized by treatment of N-substituted N,N-bis(1H-1,2,3-benzotriazol-1-ylmethyl)-amines with thioamides and zinc bromide in dry CH2Cl2 at room temperature for 48−60 h in 48−80% yields.