Naphthalenes ring cleavage

Having its pyrazolic 4-position substituted, electrophilic attack on indazoles takes place in the 3-position and in the homocycle (the 5- and 7-positions). The condensation of a benzene ring results in a decrease of the aromaticity of the pyrazole moiety, as in naphthalene compared to benzene, and therefore basic ring cleavage is easier in indazoles than in pyrazoles (Section 4.04.2.1.7(v)). 

Eaton RW, PJ Chapman (1992) Bacterial metabolism of naphthalene construction and use of recombinant bacteria to study ring cleavage of 1,2-dihydroxy naphthalene and subsequent reactions. J Bacteriol 174 7542-7554. 

Annweiler E, W Michaelis, RU Meckenstock (2002) Identical ring cleavage products during anaerobic degradation of naphthalene, 2-methylnaphthalene, and tetralin indicate a new metabolic pathway. Appl Environ Microbiol 68 853-858. 

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