Synthesis of 2,2a,4,5-tetraazabenz[cd] azulene derivatives

3-Methyl-1,8-dihydrocycloheptapyrazol-8-one hydrazone ( 5 ) reacted with triethyl ortho-formate, orthoacetate and orthopropionate to afford 2,2a,4,5-tetraazabenz[cd]azulene derivatives ( 7a-c ). 3-Methyl- ( 7b ) and 3-phenyl-substituted compounds ( 7d ) were also obtained by the reactions of 5 with acetyl and benzoyl chlorides, respectively.