Metal-Free Iodine-Catalyzed Synthesis of Fully Substituted Pyrazoles and Its Sulphenylation
Jun Sun, Jiang-Kai Qiu, Yi-Long Zhu, Cheng Guo*, Wen-Juan Hao, Bo Jiang* and Shu-Jiang Tu*
A direct and metal-free access toward fully substituted pyrazoles and its sulphenylation has been established through an iodine-mediated three-component [3+2] annulation of b-ketonitrile (or pentane-2,4-dione), arylhydrazines and aryl sulfonyl hydrazides. The reaction allows the formation of one C−S and two C−N bonds by the multiple bond cleavage including sulfur–oxygen, sulfur–nitrogen and carbon–oxygen bonds. The method features low-cost and readily accessible substrates, bond-forming efficiency, and broad substrate scopes as well as simple one-pot operation, which makes this strategy highly attractive.
J. Org. Chem. 2015, 80, 8217-8224