Pyrazine derivatives
Pyrazine derivatives R 0550Fused Nitrogen-Containing Heterocycles. Part 4. 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline Hydrazones and Flavazoles Derived Therefrom. -3-Benzoyl-1,2-dihydroquinoxalin-2-one (I) reacts with hydrazines or thiosemicarbazone to give the corresponding hydrazones [cf. (III), (V)] or thiosemicarbazone (IX), respectively. The hydrazones (III) and (V) undergo intramolecular cyclization in boiling AcOH to furnish pyrazoloquinoxalines (flavazoles) (IV) and (VI), respectively. Formation of a flavazole structure from thiosemicarbazone (IX) is achieved only in the presence of methyl 3-chloro-2-oxo-3-phenylpropionate (X) as a trap of the thiocarbamoyl moiety. -(MAMEDOV, V. A.; KALININ, A. A.; GUBAIDULLIN, A. T.; RIZVANOV, I. K.; CHERNOVA, A. V.; DOROSHKINA, G. M.; LITVINOV, I. A.; LEVIN, Y. A.; Russ.
Abstract-The polarisation of phosphorus nuclei (31P CIDNP) takes place during the homolytic reactions of dialkyl phosphites. The mechanisms of CIDNP and the corresponding chemical reactions are discussed.
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