Quinoxalines X. a new and convenient synthesis of 1H‐Pyrazolo [3,4‐b] quinoxalines (Flavazoles) |
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Authors: | Gerhard Sarodnick Torsten Linker |
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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‐pyrazolo3,4‐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‐pyrazolo3,4‐b]quinoxalines 7 proceeds smoothly and in good yield to afford 31 different flavazoles 11 and 12. |
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