Halogenation and nitration of naphtho[1,2-c][1,2,5]thiadiazole

Bromination of naphtho[1,2-c][l,2,5]thiadiazole (I) gives either an addition product, 4,5-dibromo-4,5-dihydronaphtho[1,2-c][l,2,5]thiadiazole (II), or a substitution product, 5,6-dibromonaphtho[1,2-c][l,2,5]thiadiazole (III), depending on the reaction conditions. Dehydrobromination of II gives 5-bromonaphtho[1,2-c][l,2,5]thiadiazole (IV). Chlorination of I gives the corresponding addition product V or 5-chloronaphtho[1,2-c][l,2,5]thiadiazole (VI). Compound VI can also be obtained by dehydrochlorination of V. The nitration of I produces a mixture of isomeric substitution products, 9-nitro VIII and 6-nitronaphtho[1,2-c][l,2,5]thiadiazoles (VII).