61799-28-8Relevant articles and documents
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.
New Kinetic Evidence for Inversional Mechanism in Thermal Geometrical Isomerization about Carbon-Nitrogen Double Bound
Asano, Tsutomu,Okada, Toshio
, p. 691 - 694 (2007/10/02)
Kinetic pressure and solvent effects were studied for geometrical isomerization about carbon-nitrogen double bond in N,N-dimethyl-N'--1,4-benzenediamine and 4-imino>-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one.In both of the compounds, the effects clearly demonstrate that the polarity of the reactant decreases slightly during activation, and the results can hardly be reconciled with the previously proposed rotational mechanism.
