Coordination-mediated atomic metal catalysts for cascaded transformation of β-O-4 dimeric model compound into quinoline

Here, we report the fabrication of atomic-metal catalysts for the facile cascaded transformation of lignin β-O-4 dimeric model compound into quinoline. A series of dual-metal single-atom (SA) moieties (MaC 4 and Mb 2 N 6 , where Ma and Mb represent two different metal SAs, C and N represent carbon and nitrogen atoms, respectively) are integrated on N-doped carbons with designed compositions and coordination configurations. Characterizations indicate the homogeneous distribution of uniform and modifiable SA sites, over which the electron distribution is significantly polarized due to synergistic interactions. The distinctive physicochemical properties of catalysts afford attractive performances in the cascaded synthesis of quinoline from lignin β-O-4 dimeric model compound through cascaded transformation. In a continuous flow instrument, CuC 4 /Co 2 N 6 @NC furnishes 93.7% yield of 2-phenylquinoline with a space-time yield of 75.7 g g cat h −1 . Control experiments and density functional theory calculations reveal the synergistic interactions between CuC 4 and Co 2 N 6 endow the catalyst with high efficiency in cascaded transformation.