Regioisomeric formation of the linear 1,2,4-triazolo[4′,3′:2,3][1,2,4] triazino[5,6-b]indole from 3-hyrazino-1,2,4-triazino[5,6-b]indole derivatives

Oxidative cyclisation of the ethylidene derivatives of 5-allyl-3-hydrazino-1,2,4-triazino[5,6-b]indole (7) and 8-bromo3-hydrazino-5H-1,2,4-triazino[5,6-blindole (8) gave regioselectively the linear isomers, 10-allyl-3-methyl-1,2,4-triazolo[4',3':2,3][1,2,4]triazino-[5,6-b]indole (15) and 7-bromo-3-methyl-10H-1,2,4-triazolo[4',3':2,3][1,2,4]triazino-[5,6-b]indole (16), respectively. They were also obtained by the clehydrative cyclisation of 5 and 6 respectively with acetic acid as well as by the condensation of the N-allyl- (22) or 5-bromo-isatin (23) with 3,4-diamino-5-methyl-4H-1,2,4-triazole (24). The corresponding allyl derivatives 17 and 18 were also synthesised. Some sugar derivatives of 5 were prepared.