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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Synthetic approaches to phthalazines: C-N bond cleavage in 2'-benzylbenzohydrazides during reaction with polyphosphoric acid

DB Paul

Australian Journal of Chemistry 37(4) 893 - 901
Published: 1984

Abstract

Reaction of 2'-benzylbenzohydrazides with concentrated polyphosphoric acid gave 2,5-diaryl-1,3,4- oxadiazoles and a polybenzyl. Cyclodehydration to phthalazines was not observed. It is inferred from product substitution patterns that CH2-N bond cleavage occurs with polybenzyls forming from the benzyl moiety and oxadiazoles from the benzohydrazide fragment. Other reported reactions which generate benzyl fragments lead to bibenzyl and are considered to involve trapping of the cleavage products within a solvent cage. The observed production of polybenzyls is therefore interpreted in terms of the formation of free benzyl fragments.

A tetrahydrophthalazine derivative was produced from the addition of diethyl azodicarboxylate to the photodiene of o-methylbenzophenone, but this could not be converted into a phthalazine.

https://doi.org/10.1071/CH9840893

© CSIRO 1984

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