Guo Shenghai, Zhai Jianhui, Fan Xuesen
Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China.
Org Biomol Chem. 2017 Feb 7;15(6):1521-1529. doi: 10.1039/c6ob02699k.
An efficient and facile protocol for the synthesis of quinazolinone-fused tetracyclic compounds through an iodine-mediated one-pot cascade reaction of 2'-bromoacetophenones with 2-aminobenzohydrazides or 2-aminobenzamides is reported. With 2-aminobenzohydrazides as the substrates, the reaction gave 5H-quinazolino[3,2-b]cinnoline-7,13-diones in moderate to good yields under metal-catalyst-free conditions. With 2-aminobenzamides as the substrates and CuBr as the catalyst, on the other hand, it afforded tryptanthrin derivatives with good efficiency. Mechanistically, the formation of the tetracyclic systems is initiated by iodination and oxidation of 2'-bromoacetophenones followed by a cascade procedure consisting of cyclocondensation, aromatization and intramolecular cyclization of the in situ formed 2-bromoarylglyoxals with 2-aminobenzohydrazides or 2-aminobenzamides, respectively.
报道了一种通过2'-溴苯乙酮与2-氨基苯甲酰肼或2-氨基苯甲酰胺的碘介导一锅串联反应合成喹唑啉酮稠合四环化合物的高效简便方法。以2-氨基苯甲酰肼为底物，该反应在无金属催化剂条件下以中等至良好的产率得到5H-喹唑啉并[3,2-b]噌啉-7,13-二酮。另一方面，以2-氨基苯甲酰胺为底物并以CuBr为催化剂时，能高效得到色胺酮衍生物。从机理上讲，四环体系的形成是由2'-溴苯乙酮的碘化和氧化引发的，随后是原位形成的2-溴芳基乙二醛分别与2-氨基苯甲酰肼或2-氨基苯甲酰胺进行环缩合、芳构化和分子内环化的串联过程。
