62349-59-1Relevant academic research and scientific papers
A new regiospecific synthesis method of 1H-pyrazolo[3,4-b]quinoxalines – Potential materials for organic optoelectronic devices, and a revision of an old scheme
Danel, Andrzej,Wojtasik, Katarzyna,Szlachcic, Pawe?,Gryl, Marlena,Stadnicka, Katarzyna
, p. 5072 - 5081 (2017/07/28)
A series of 6-substituted-1,3-diphenyl-1H-pyrazolo[3,4-b]quinoxalines were prepared using a new synthetic pathway: reductive cyclization of appropriate 5-(o-nitrophenyl)-pyrazoles with ferrous oxalate or triphenylphosphine. The main advantage of this procedure is that, contrary to the older protocols of pyrazolo[3,4-b]quinoxaline synthesis, this method allows for a substituent to be introduced to the carbocyclic ring without the formation of isomers. The pyrazole ring can also be modified to some extent. Furthermore, we propose a new mechanism for the oldest reported pyrazolo[3,4-b]quinoxaline synthesis, based on the condensation between o-phenylenediamine and 3,4-pyrazolin-5-diones.
