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

Rongrong Xie; Yi Xiao; Yiwen Wang; Zhi-Wei Xu; Ning Tian; Shiqing Li; Ming-Hua Zeng

doi:10.1021/acs.orglett.3c00542

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

Org Lett. 2023 Apr 14;25(14):2415-2419. doi: 10.1021/acs.orglett.3c00542. Epub 2023 Apr 4.

Authors

Rongrong Xie¹, Yi Xiao¹, Yiwen Wang¹, Zhi-Wei Xu², Ning Tian², Shiqing Li^{1

3}, Ming-Hua Zeng^{1

2}

Affiliations

¹ Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional Materials, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004, China.
² State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, 15 Yu Cai Road, Guilin 541004, China.
³ State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.

PMID: 37014715
DOI: 10.1021/acs.orglett.3c00542

Abstract

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.