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)