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Quinoxalines X . a new and convenient synthesis of 1 H ‐Pyrazolo [3,4‐ b ] quinoxalines (Flavazoles)
Author(s) -
Sarodnick Gerhard,
Linker Torsten
Publication year - 2001
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570380404
Subject(s) - chemistry , quinoxaline , hydrazine (antidepressant) , yield (engineering) , acylation , alkylation , combinatorial chemistry , organic chemistry , medicinal chemistry , catalysis , chromatography , materials science , metallurgy
Abstract Dedicated to Professor Gerhard Kempter on the occasion of his 70 th birthday Quinoxaline‐2‐aldoximes and ‐ketoximes ( 6 ) react with hydrazine, alkylhydrazines or arylhydrazines under acidic conditions to afford l H ‐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 l H ‐pyrazolo[3,4‐ b ]quinoxalines 7 proceeds smoothly and in good yield to afford 31 different flavazoles 11 and 12.