Electrochemical synthesis of pyrido[1,2-a]pyrimidine derivatives. II. Electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4H-pyrido[1,2-a]pyrimidine in aqueous media

E. Szebényi-Gyory, V. Kovács-Mindler, I. Hermecz, B. Podányi, J. Brlik

Research output: Contribution to journalArticle

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Abstract

The electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4 H-pyrido[l,2-a]pyrimidine (base and HCl salt) was investigated by polarography and controlled potential electrolysis in aqueous buffered solutions at different pH values on a dropping mercury electrode and a mercury pool cathode. Controlled potential electrolyses performed in methanolic borate buffer solution (pH=9, 10) at the first polarographic wave (1.45 V vs SCE) gave a stable C-8-coupled hydrodimer (III) in a one-electron process with a product yield of 52%. Reduction performed in alkaline methanolic solution (pH=13.4), at the second polarographic wave (- 1.86 V vs SCE) showed a dihydromonomer (IV) formation with a product yield of 87%, in a two-electron process. The structures of the reduction products were demonstrated by1H and13C NMR spectroscopy as well as by mass spectrometric (MS) data. Two different routes were suggested for the reduction mechanism; a one-electron process involving a neutral radical intermediate formation accompanied by a rapid dimerization and one involving the primarily-formed neutral radical by a second electron uptake and protonation to give the dihydroderivative.

Original languageEnglish
Pages (from-to)145-150
Number of pages6
JournalJournal of Applied Electrochemistry
Volume15
Issue number1
DOIs
Publication statusPublished - Jan 1985

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Derivatives
Electrons
Mercury
Electrolysis
Polarographic analysis
Borates
Dimerization
Protonation
Nuclear magnetic resonance spectroscopy
Buffers
Cathodes
Salts
Electrodes
pyrimidine

ASJC Scopus subject areas

  • Electrochemistry

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Electrochemical synthesis of pyrido[1,2-a]pyrimidine derivatives. II. Electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4H-pyrido[1,2-a]pyrimidine in aqueous media. / Szebényi-Gyory, E.; Kovács-Mindler, V.; Hermecz, I.; Podányi, B.; Brlik, J.

In: Journal of Applied Electrochemistry, Vol. 15, No. 1, 01.1985, p. 145-150.

Research output: Contribution to journalArticle

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abstract = "The electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4 H-pyrido[l,2-a]pyrimidine (base and HCl salt) was investigated by polarography and controlled potential electrolysis in aqueous buffered solutions at different pH values on a dropping mercury electrode and a mercury pool cathode. Controlled potential electrolyses performed in methanolic borate buffer solution (pH=9, 10) at the first polarographic wave (1.45 V vs SCE) gave a stable C-8-coupled hydrodimer (III) in a one-electron process with a product yield of 52{\%}. Reduction performed in alkaline methanolic solution (pH=13.4), at the second polarographic wave (- 1.86 V vs SCE) showed a dihydromonomer (IV) formation with a product yield of 87{\%}, in a two-electron process. The structures of the reduction products were demonstrated by1H and13C NMR spectroscopy as well as by mass spectrometric (MS) data. Two different routes were suggested for the reduction mechanism; a one-electron process involving a neutral radical intermediate formation accompanied by a rapid dimerization and one involving the primarily-formed neutral radical by a second electron uptake and protonation to give the dihydroderivative.",
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T1 - Electrochemical synthesis of pyrido[1,2-a]pyrimidine derivatives. II. Electrochemical reduction of 2,6-dimethyl-3-ethyl-4-oxo-4H-pyrido[1,2-a]pyrimidine in aqueous media

AU - Szebényi-Gyory, E.

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AU - Brlik, J.

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