Interaction of 1,3λ4δ2,2,4-benzodithiadiazines with neutral and charged S-electrophiles: SCl2, C6F5SCl, and NS2+
Reactions of 1,3λ 4 δ 2 ,2,4-benzothiadiazines with SCl 2 , C 6 F 5 SCl, and [NS 2 ][SbF 6 ] leading to 1,2,3-benzodithiazolium salts (Herz salts) were investigated. The relative rate of reaction with SCl 2 significantly depends on the nature of the substituent and its position in the carbocycle. Halogen substituents Cl, Br, and I slow down the reaction, especially if located closely to the heterocycle (positions 5 and 8). In the case of C 6 F 5 SCl and R = H, chlorination of the carbocycle and opening of the heterocycle also takes place with the formation of 7-chloro-1,3λ 4 δ 2 ,2,4-benzothiadiazine and C 6 F 5 –S–N=S=N–Ar (Ar = 2-Cl-6-F 5 C 6 SC 6 H 3 ), respectively. In the reaction with NS 2 + , along with contraction of the heterocycle, also its expansion occurs with the formation of 1,2,4λ 4 δ 2 ,3,5-benzotrithiadiazepine.