Mechanistic Insights into the Ligand-Directed Divergent Synthesis of 2-Benzazepine Derivatives via Ni-Catalyzed Tunable Cyclization/Cross-Coupling: A DFT Study

Tao Liu; Zitong Meng; Yihang Zhou; Teng Wang; Kang Lv

doi:10.1021/acs.inorgchem.3c02853

Mechanistic Insights into the Ligand-Directed Divergent Synthesis of 2-Benzazepine Derivatives via Ni-Catalyzed Tunable Cyclization/Cross-Coupling: A DFT Study

Inorg Chem. 2023 Oct 30;62(43):17946-17953. doi: 10.1021/acs.inorgchem.3c02853. Epub 2023 Oct 18.

Authors

Tao Liu^{1

2}, Zitong Meng^{1

2}, Yihang Zhou¹, Teng Wang^{1

2}, Kang Lv¹

Affiliations

¹ School of Chemistry, Chemical Engineering and Materials, Jining University, Qufu 273155, Shandong, China.
² School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, Shandong, China.

PMID: 37851378
DOI: 10.1021/acs.inorgchem.3c02853

Abstract

The detailed mechanisms of Ni-catalyzed ligand-controlled cyclization/cross-coupling of o-bromobenzenesulfonyl acrylamide (1a) with trifluoromethyl alkene were investigated by DFT calculations. The computational results support a single-electron reduction of Ni^II precatalyst to give BrNi^IL species, which would react with 1a via oxidative addition to afford the (Ar)Ni^IIILBr₂ complex. The subsequent cyclizations did not proceed until (Ar)Ni^IIILBr₂ was reduced to the key (Ar)Ni^IL complex. For the bpy-involving reaction, the subsequent steps include nucleophilic attack to the carbonyl carbon atom, N-C bond breaking, intramolecular migratory insertion, as well as concerted C-C cross-coupling and β-F elimination. While the ligand of terpyridine promotes the 7-endocyclization followed by stepwise migratory insertion and β-F elimination to afford 2-benzazepine 2,5-dione. For both reactions, a theoretical study implied that the most favorable mechanism involved a Ni^I-Ni^III-Ni^I catalytic cycle. The origins of the chemoselectivity, coupled with the factors responsible, were addressed.