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Synthesis and structural analysis of 5-cyanodihydropyrazolo[3,4-b]pyridines

✍ Scribed by Jairo Quiroga; Silvia Cruz; Braulio Insuasty; Rodrigo Abonia; Justo Cobo; Adolfo Sánchez; Manuel Nogueras; John N. Low

Publisher
Journal of Heterocyclic Chemistry
Year
2001
Tongue
English
Weight
99 KB
Volume
38
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

Several new 3‐aryl‐5‐cyanopyrazolo[3,4‐b]pyridines were easily prepared from 3‐amino‐5‐arylpyrazoles and α‐cyanochalcones. Structural analysis using NMR solution studies revealed the 2__H__‐tautomers as the preferred tautomer in solution (DMSO‐d~6~). X‐ray diffraction confirmed the 2__H__‐tautomers as the unique tau‐tomer species in the crystalline state as well. Geometry optimization of 1__H__ and 2__H__‐tautomers at semi‐empirical levels (AM1, MINDO/3) were performed, indicating that in all cases the 2__H__‐tautomers are more stable than the corresponding 1__H__‐tautomers.

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