Tracking the Process of Domino Ring‐Opening and Coupling of Fused Imidazole and Direct Observation of Peroxide Intermediates

• Published in: Chinese journal of chemistry Vol. 41; no. 17; pp. 2089 - 2094
• Main Authors: Wang, Yu, Luo, Mei‐Lian, Cai, Jin, Zhang, Tao, Wu, Yu‐Jie, Song, Ming‐Da, Liu, Bin, Zeng, Ming‐Hua
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY‐VCH Verlag GmbH & Co. KGaA 01.09.2023; Wiley; Wiley Subscription Services, Inc
• Subjects: Alkylation; Chemistry; Chemistry, Multidisciplinary; Coupling (molecular); Crystallography; Crystals; C‐C coupling; Dehydration; Density functional calculations; Domino reaction; Imidazole; Intermediates; Ionization; Isotopes; Mass spectrometry; Mass spectroscopy; NMR; Nuclear magnetic resonance; Oxidation; Oxygen; Physical Sciences; Process tracking; Reaction intermediates; Ring opening; Science & Technology; Single crystals; Tracking; C-C coupling; COMPLEX; CASCADE REACTIONS; Density functional calculations; Ring-opening; MASS-SPECTROMETRY; Domino reaction; Process tracking; N-ALKYLIMIDAZOLE LIGANDS; CLUSTERS; CHEMISTRY; Mass spectrometry; Isotopes
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.202300156

Comprehensive Summary A domino ring‐opening and coupling of imidazolyl annulated heterocycles 1 (1a: 4‐methyl‐1‐(1‐methyl‐1H‐benzo[d]imidazol‐2‐yl)‐4H‐ benzo[d]imidazo[1,5‐a]imidazole, 1b: 1‐(1,5‐dimethyl‐1H‐benzo[d]imidazol‐2‐yl)‐4,7‐dimethyl‐4H‐benzo[d]imidazo[1,5‐a]imidazole) with dioxygen was developed at solvothermal condition, leading to conjugated 1,2‐diamidoalkenes derivatives 2 ((E)‐ArCONHArC=CArNHCOAr (Ar: 1‐methyl‐1H‐benzo[d]imidazolyl (2a), 1,5‐dimethyl‐1H‐benzo[d]imidazolyl (2b))) as single crystals directly. The reaction process was tracked by electrospray ionization mass spectrometry (ESI‐HRMS) and a series of reaction intermediates are detected. 18O2 labeling experiment verified the source of oxygen in 2. Combining evidence from control experiments, nuclear magnetic resonance (NMR) tracking, and crystallography, a seven‐step reaction pathway involving oxygen addition, ring opening, Friedel‐Crafts alkylation, oxidation, and dehydration was proposed and further supported by DFT calculation. The domino reaction of fused imidazole with dioxygen at solvothermal condition is studied, which produced the first bicyclic substituted 1,2‐diamidoalkenes derivatives. A series of key intermediates including peroxide species is observed through electrospray ionization mass spectrometry (ESI‐HRMS).