A new regiospecific synthesis method of 1 H -pyrazolo[3,4- b ]quinoxalines – Potential materials for organic optoelectronic devices, and a revision of an old scheme
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
使用一种新的合成途径制备了一系列6-取代的1,3-二苯基-1H-吡唑并[3,4- b ]喹喔啉:将适当的5-(邻硝基苯基)-吡唑与草酸亚铁或三苯基膦。该方法的主要优点是,与吡唑并[3,4- b ]喹喔啉合成的旧方案相反,该方法允许将取代基引入碳环而不形成异构体。吡唑环也可以进行一定程度的修饰。此外,我们提出了一种新的机制,据报道,邻苯二酚之间的缩合反应可用于最古老的吡唑并[3,4- b ]喹喔啉合成。-苯二胺和3,4-吡唑啉-5-二酮。
New Synthesis of Pyrazolo[3,4-<i>b</i>][1,4,5]benzothiadiazepine, -[1,4,5]benzoxadiazepine, -[1,4,5]benzotriazepine and Pyrazolo[3,4-<i>b</i>]quinoxaline Derivatives
作者:Eman A. El-Rady
DOI:10.1002/jccs.200400129
日期:2004.8
New pyrazolo[3,4-b][1,4,5]benzothiadiazepine and its analogues 3 have been obtained by reaction of 4-nitrosopyrazoles 1 with 2-aminothiophenol 2a and its analogues 2b,c. Under fused conditions, dipyrazolyl derivatives 7a was obtained with a trace amount of quinoxaline 5a. On the other hand, 5b and 7b were obtained in equal amounts. A proposed pathway is presented.
Sachs; Becherescu, Chemische Berichte, 1903, vol. 36, p. 1137
作者:Sachs、Becherescu
DOI:——
日期:——
——
作者:V. A. Mamedov
DOI:10.1023/a:1023415301274
日期:——
3-Benzoyl-1,2-dihydroquinoxalin-2-one reacts with hydrazine and thiosemicarbazide to give the corresponding hydrazone and thiosemicarbazone. The reaction with arylhydrazines yields 3-(alpha-arylazoben-zylidene)-1,2,3,4-tetrahydroquinoxalin-2-ones which are tautomeric to the respective arylhydrazones. On heating in boiling acetic acid, the products of both types undergo intramolecular cyclocondensation with formation of 3-phenylpyrazolo[3,4-b]quinoxalines (3-phenylflavazoles). 3-Benzoyl-1,2-dihydroquinoxalin2-one thiosemicarbazone gives rise to flavazole structure only in the presence of methyl 3-chloro-2-oxo-3-phenylpropionate as a trap of thiocarbamoyl moiety. The cyclization of 3-(alpha-hydrazonobenzyl)-1,2-dihydroquinoxalin-2-one is accompanied by formation of quinoxalyl ketone azine.
PILLAI P. MADHAVAN; RAMABHADRAN P., INDIAN J. CHEM., 25,(1986) N 2, 215-217