An approach to the synthesis of a cycloheptapyrazole (1,2-diaza-azulene)

Abstract

2,6-Dihydro-5,7-dimethylcycloheptapyrazol-6-one was prepared by base-catalysed condensation of diethyl ketone with pyrazole-3,4-dicarbaldehyde. On treatment with phenyl-lithium, the tropone was converted into 2,6-dihydro-5,7-dimethyl-6-phenylcycloheptapyrazol-6-ol (IVb). This alcohol gave the perchlorate of a cyclic dimer of 5,7-dimethyl-6-phenylcycloheptapyrazole (I) with perchloric acid. Spectral data in support of this dimer are presented.