Metal-Free Assembly of Polysubstituted Pyridines from Oximes and Acroleins

Metal-Free Assembly of Polysubstituted Pyridines from Oximes and Acroleins

Huawen Huang*, Jinhui Cai, Lichang Tang, Zilong Wang, Feifei Li, and Guo-Jun Deng*
Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China

DOI: 10.1021/acs.joc.5b02624
J. Org. Chem. 

Abstract:
 

Transition-metal-catalyzed synthesis of N-heterocycles from oximes has been previously well established. In this paper, for the first time a metal-free protocol with the combinational employment of iodine and triethylamine has been demonstrated to be effective to trigger the oxime-based synthesis of pyridines with high chemo-selectivity and wide functional group tolerance. A broad range of functional pyridines were prepared in moderate to excellent yields. While neither iodine nor triethylamine could trigger this transformation, mechanistic experiments indicated a radical pathway for the reaction. The resultant 2-aryl-substituted pyridines have been proved to be versatile building blocks in a range of transition-metal-catalyzed C−H functionalization reactions.

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