SYNTHESIS OF 2 NOVEL BICYCLIC SYSTEMS, IMIDAZO[1,5-D]-AS-TRIAZINE AND IMIDAZO[1,2-D]-AS-TRIAZINE

4‐Imidazolecarboxyaldehyde was condensed with methyl dithiocarbazinate and with ethyl carbazate, the resulting hydrazones were subjected to thermolysis in diphenyl ether at 175–240, to give imidazo[1,5‐d]‐as‐triazine‐4(3H)thione and imidazo[1,5‐d]‐as‐triazin‐4(3H)one, respectively. A number of 2‐, 5‐, and 2,5‐substituted 4‐imidazolecarboxaldehydes were also carried through this scheme. The same sequence of reactions with 2‐imidazolecarboxaldehyde gave the novel system imidazo[1,2‐d]‐αs‐triazine‐5‐(6H)‐thione. Upon treatment with sodium hydride and methyl iodide, imidazo[1,5‐d]‐as‐triazine‐4(3H)thione and imidazo[1,2‐d]‐as‐triazine‐5(6H)‐thione gave 4‐methylthioimidazo[1,5‐d]‐as‐triazine and 5‐methylthioimidazo[1,2‐d]‐as‐triazine, respectively. Displacement of the thiomethyl group was achieved with a selection of amine reagents in both of the above cases. Copyright © 1979 Journal of Heterocyclic Chemistry