A. V. Denisenko, A. V. Tverdokhlebov, A. Tolmachev
2011
Citations
0
Influential Citations
5
Citations
Journal
Synthesis
Abstract
Acylation of (1,3-dimethylbenzimidazol-2-ylidene)-, (3-methylbenzothiazol-2-ylidene)-,and (3,4-dimethylthiazol-2-ylidene)-acetonitriles with 1-(cyanoacetyl)-3,5-dimethylpyrazole wasfound to proceed at the exocyclic carbon atom, yielding the appropriate2-heterylidene-3-oxopentanedinitriles. Treatment of the prepareddinitriles with hydrobromic acid in refluxing acetic acid afforded2-(6-amino-2-bromo-4-hydroxypyridin-3-yl)-substituted quaternarysalts of benzimidazolium, benzothiazolium, and thiazolium. Theirstructures were confirmed unambiguously by X-ray crystallographicstudies. Reduction of these quaternary salts with excess sodiumborohydride yielded the corresponding dihydro (in the case of benzoazoles)or tetrahydro (in the case of thiazole) derivatives, which wereshown to be synthetic equivalents of the title nicotinaldehyde.