Bonded- and discreted-Lindqvist hexatungstate-based copper hybrids as heterogeneous catalysts for the one-pot synthesis of 2-phenylquinoxalines via 2-haloanilines with vinyl azides or 3-phenyl-2 H -azirines

• Published in: Dalton transactions : an international journal of inorganic chemistry 2020-10, Vol.49 (40), p.13993-13998
• Main Authors: Shen, Guodong, Wang, Zeyou, Huang, Xianqiang, Gong, Shuwen, Zhang, Jiangong, Tang, Zhenfei, Sun, Manman, Lv, Xin
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/D0DT02625E

One bonded- and one discreted-Lindqvist hexatungstate-based copper hybrids (Cu-POMs) ([Cu 2 (O)OH(phen) 2 ] 2 [W 6 O 19 ]·6H 2 O ( 1 ) and [Cu 2 (phen) 4 Cl] [HW 6 O 19 ]·2H 2 O ( 2 ) (phen = 1,10-phenanthroline)) were controllably synthesized and routinely characterized. Cu-POMs 1–2 consisted of identical [W 6 O 19 ] unit and similar copper–phen complexes, the two units are bonded via four Cu–O chemical bonds in compound 1 ; however, compound 2 is discreted and stabilized by intermolecular electrostatic interactions. Importantly, these Cu-POMs catalysts were first applied in the novel reaction for the preparation of 2-phenylquinoxalines via the one-pot coupling and oxidation reactions of 2-haloanilines with vinyl azides or 3-phenyl-2 H -azirines under mild conditions, and Cu-POMs 1 showed higher catalytic performance in good yields (79–84%). The reactions exhibit some functional group tolerance and allow for the preparation of a number of 2-phenylquinoxalines.