hrvatski

Betainska struktura nekih pironilpirazola

We have already reported the synthesis and structure of some pyronylpyrazoles.1 The structure of N, N-disubstituted derivatives of pyronylpyrazoles Are the subject of the present communication. The structure of compounds 1-6 can be described by a covalent resonance form (A) and a dipolar one (B) which presents the heterocyclic betaine structure. Heterocyclic betaines have been the subject of extensive investigation. 1-H and 13-C NMR data of compounds 1-6 are consistent with their dipolar nature (form B). The larger 1-J coupling constants (C-4, H and N-CH3) and pyrazole carbons chemical shift values are in agreement with those reported for pyrazolium salts and can be explained by increased electron deficiency of the pyrazole ring.

Betaini; Pironilpirazoli

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