Synthesis of new functionalized derivatives of 1,2,4-triazolo[4′,3′:2,3][1,2,4]triazino[5,6-b]indole

New functionalized 1,2,4-triazolo[4',3':2,3][1,2,4]triazino[5,6-b]indole derivatives were synthesized via reaction of the hydrazonoyl halides with 2,4-dihydro-3H-1,2,4-triazino[5,6-b]indole-3-thione or its 3-methylthio derivative. The mechanism and the regioselectivity of the studied reactions are discussed.