Article

Quinoxalines X. a new and convenient synthesis of 1H‐Pyrazolo [3,4‐b] quinoxalines (Flavazoles)

Department of Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, D-14476 Golm, Germany
Journal of Heterocyclic Chemistry (impact factor: 1.22). 03/2009; 38(4):829 - 836. DOI:10.1002/jhet.5570380404 pp.829 - 836

ABSTRACT Dedicated to Professor Gerhard Kempter on the occasion of his 70th birthday Quinoxaline-2-aldoximes and -ketoximes (6) react with hydrazine, alkylhydrazines or arylhydrazines under acidic conditions to afford lH-pyrazolo[3,4-b]quinoxalines (flavazoles) (1). Since the oximes (6) are easily available from phenylenediamine, the herein described methodology provides a convenient two step entry to various functionalized flavazoles. Furthermore, acylation and alkylation of the 1-unsubstituted lH-pyrazolo[3,4-b]quinoxalines 7 proceeds smoothly and in good yield to afford 31 different flavazoles 11 and 12.

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Keywords

1-unsubstituted lH-pyrazolo[3,4-b]quinoxalines 7 proceeds
 
31 different flavazoles 11
 
70th birthday Quinoxaline-2-aldoximes
 
acylation
 
arylhydrazines
 
convenient
 
good yield
 
lH-pyrazolo[3,4-b]quinoxalines
 
phenylenediamine
 
Professor Gerhard Kempter
 

Gerhard Sarodnick