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Chemical properties of ylidene derivatives of azines. 4. Structures of the products of protonation and transformation of dihydroazinylidenecyanoacetic esters in concentrated sulfuric acid

✍ Scribed by I. V. Oleinik; O. A. Zagulyaeva; A. Yu. Denisov; V. P. Mamaev

Publisher: Springer US
Year: 1990
Tongue: English
Weight: 582 KB
Volume: 26
Category: Article
ISSN: 0009-3122
DOI: 10.1007/bf00509712

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✦ Synopsis

It was demonstrated by UV and 13C NMR spectroscopy that in concentrated sulfuric acid ylidene derivatives of dihydropyridine (Ia) and dihydropyridazine (lla) have aromatic structures Ib and lIb, while derivatives of dihydropyrimidines Ilia and IVa, dihydropyrazine Va, and dihydro-s-triazine Via retain ylidene structures llIb-VIb, respectively, which determines their greater stability in these solutions. When solutions of lb-VIb in 95% H2S04 were allowed to stand, they were converted to the corresponding azinylmalonic ester monoamides or azinylacetamides, depending on the reaction temperature.

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