Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials ...Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.展开更多
Chengdu Branch,Chinese Science Academy,Chengdu610041)abstract:[Mn(ECZ)abstract: 3 ](NO 3 )abstract: 2 is newly prepared by the aqueous solutions of Mn(NO 3 )abstract: 2 and ethyl carbazate(ECZ)abstract:.The crystal st...Chengdu Branch,Chinese Science Academy,Chengdu610041)abstract:[Mn(ECZ)abstract: 3 ](NO 3 )abstract: 2 is newly prepared by the aqueous solutions of Mn(NO 3 )abstract: 2 and ethyl carbazate(ECZ)abstract:.The crystal structure has been determined by X-ray crystal diffraction analysis.It belongs to monoclinic with space group of P2 1 /n.The crystal parameters are:a=1.3974(2)abstract:nm,b=0.8796(2)abstract:nm,c=3.4322(7)abstract:nm,β=9 1.25(1)abstract:°,V=4.2175(1)abstract:nm 3 ,Z=8.Its molecular weight is491.30.Mn 2+ is located on the center of the molecular structure.Ethyl carbazate serves a s a bidentate ligand which coordinates to the metal cations with its carbonyl ox ygen atom and the terminal hydrazine nitrogen atom,forming five-member chelatin g rings,and three such rings are formed in each molecule.The coordination number of the metal ion is six and the coordination configuration of the cen-tral ion is octahedral.Specially,antimer configuration phenomenon is found in the molecu le.The complex is fur-ther characterized by element analysis and IR measurement s.The thermal decomposition mechanism is studied by using TG-DTG and DSC techni ques.CCDC:215675.展开更多
基金supported by the Hunan Provincial Natural Science Foundation of China (2019JJ20008)the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering
文摘Quinoxaline-3-carboxylates and analogues are prevalent key structural motifs in bioactive natural products and synthetic drugs.However, the practical protocol for preparation of these motifs from simple raw materials under mild conditions remains rare. In this article, we report a facile protocol for the efficient preparation of various quinoxaline-3-carbonyl compounds(30 examples,63%–92%) through oxidation coupling of quinoxalin-2(1H)-ones with readily available carbazates(or acyl hydrazines) in the presence of K_2S_2O_8 as an oxidant in metal-and base-free conditions. When tert-butyl carbazate was used as the coupling reagent,the decarboxylation product 3-(tert-butyl)-1-methylquinoxalin-2(1H)-one was obtained. The application of this process into a gram-scale synthesis can be easily accomplished. Mechanistic investigations reveal that the functionalization of quinoxalin-2(1H)-ones via a free-radical pathway.
文摘Chengdu Branch,Chinese Science Academy,Chengdu610041)abstract:[Mn(ECZ)abstract: 3 ](NO 3 )abstract: 2 is newly prepared by the aqueous solutions of Mn(NO 3 )abstract: 2 and ethyl carbazate(ECZ)abstract:.The crystal structure has been determined by X-ray crystal diffraction analysis.It belongs to monoclinic with space group of P2 1 /n.The crystal parameters are:a=1.3974(2)abstract:nm,b=0.8796(2)abstract:nm,c=3.4322(7)abstract:nm,β=9 1.25(1)abstract:°,V=4.2175(1)abstract:nm 3 ,Z=8.Its molecular weight is491.30.Mn 2+ is located on the center of the molecular structure.Ethyl carbazate serves a s a bidentate ligand which coordinates to the metal cations with its carbonyl ox ygen atom and the terminal hydrazine nitrogen atom,forming five-member chelatin g rings,and three such rings are formed in each molecule.The coordination number of the metal ion is six and the coordination configuration of the cen-tral ion is octahedral.Specially,antimer configuration phenomenon is found in the molecu le.The complex is fur-ther characterized by element analysis and IR measurement s.The thermal decomposition mechanism is studied by using TG-DTG and DSC techni ques.CCDC:215675.
