Hydrazine-Halogen Exchange Strategy Toward N=N-Containing Compounds and Process Tracking for Mechanistic Insight

作者：Xie, Rongrong; Xiao, Yi; Wang, Yiwen; Xu, Zhi-Wei; Tian, Ning; Li, Shiqing^*; Zeng, Ming-Hua^*

来源：Organic Letters, 2023, 25(14): 2415-2419.

DOI：10.1021/acs.orglett.3c00542

• AROMATIC AZO-COMPOUNDS
• BOC ARYL HYDRAZINES
• EFFICIENT SYNTHESIS
• COUPLING REACTIONS
• CASCADE REACTION
• HALIDES
• ANILINES
• AZOBENZENES
• DERIVATIVES
• FACILE

An anhydride-promoted traceless hydrazine-I/Br exchange strategy is reported, where hydrazine hydrate and cyclic/linear iodonium, including rarely explored cyclic bromonium, are converted to benzo[c]-cinnolines/ azobenzenes in one pot. The reaction proceeds through diacylation (first and second C-N formation), N,N'-diarylation (third and fourth C-N formation), and deacylation/oxidation ( 2 C-N cleavages and 1 N=N formation). The reaction mechanism is investigated by isolating multiple intermediates and kinetic studies. Furthermore, time-dependent electrospray ionization mass spectrometry (TD ESI-MS) was applied to track the process by detecting most intermediates. The complex [Cu-III(iodobiphenyl)(bipy)I](+) (Int-C) was detected for the first time, giving evidence for oxidative addition of cyclic iodonium to Cu catalyst. Another complex [Cu-I(PHA)(bipy)] (Int-B) via ligand-exchange between the hydrazide and Cu catalyst was also detected, indicating a two-path initial activation process.

• 单位
  桂林理工大学; 南开大学