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The synthesis and structure elucidation of new pyrazolo[3,4‐b][1,4]diazepines and pyrazolo[3,4‐b]pyrazines are reported and the characterisation of isomers and tautomers by proton and carbon‐13 nmr are discussed. In some case only NOE experiments allow us to identify the isomeric structure.

The synthesis, structure elucidation and chemotherapeutic activity of novel 3‐quinolinecarboxylic acid derivatives are reported. These derivatives are characterized by a group (1‐imidazolyl)phenylmethyl attached to the 7‐position and chloro 10a, fluoro 10b or methoxy 10c appended to the 6‐position.

Reaction of hydroxylamine with benzoylacetaldehyde gives a derivative which, in solution, is a mixture of (I; R = H), (11; R = H), and (111; R = H), whereas that from the reaction with benzoylacetone is, exclusively, (I ; R = Me) ; acetylation of the former gives (VI) and true diacetates (V; R = H), whereas that of the latter gives only true diacetates (V; R = Me).THE spectral properties of the known solid mono-oxime of benzoylacetaldehyde,l m.p. 85-7", are only interpretable by accepting that, in solution, it exists as an equiEibrium mixture of the two open oximes (11) and (111; R = H) and the "cyclo-oxime" ( I ; R = H). This is the first time we have found such an (n.m.r. observable) equilibrium mixture of open and cyclic forms in derivatives of this kind.2 Spectral properties: i.r. : 3200 (broad band; associated OH), 1672 (C=O), and 1640 cm.-l (C=N) (KBr); 3600 (free OH) and 1695 cm.-l (C=O)