Ring Cleavage of Some Bicylic Compounds Derived from 1,2,4-Triazine

Ring cleavage occurred when 1,2,4-triazino-1,2,4-triazines (3), (4) and (5) were treated with concentrated hydrochloric acid to yield N-substituted triazines (7) and (8). These confirm the given configuration assigned to the isomeric triazinotriazines. 6-Methyl-2-phenyl-7H-oxazolo [3,2-b][1,2,4]-triazin-7-one (9) underwent ring cleavage on treatment with sodium alkoxide to afford 3-alkoxy-1,2,4-triazines (10). Treatment of (9) with concentrated hydrochloric acid gave 6-methyl-2-phenacyl-1,2,4-triazin-3,5(4H)-dione (6). Under basic conditions, degradation of (9) occurred followed by ring closure of an intermediate to give 1-amino-4-phenylimidazole-2(3H)-one (11)