Synthesis of Tri- and Tetrasubstituted Pyrazoles via Ru(II) Catalysis: Intramolecular Aerobic Oxidative C-N Coupling
Jiantao Hu, Shi Chen, Yonghui Sun , Jing Yang and Yu Rao*
*Department of Pharmacology and Pharmaceutical Sciences, School of Medicine and School of Life Sciences, Tsinghua University, Beijing 100084, China, Email: yraomail.tsinghua.edu.cn
J. Hu, S. Chen, Y. Sun, J. Yang, Y. Rao, Org. Lett., 2012, 14, 5030-5033.
DOI: 10.1021/ol3022353 (free Supporting Information)
An unprecedented ruthenium(II)-catalyzed oxidative C-N coupling method enables a facile intramolecular synthesis of various synthetically challenging tri- and tetrasubstituted pyrazoles in the presence of oxygen as oxidant. The reaction demonstrates excellent reactivity, functional group tolerance, and high yields.
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