Kemp-type elimination of 1-arylsulfonyl-3-iodo-1H-indazoles

Abstract

An intriguing ring-opening reaction of 1-arylsulfonyl-3-iodo-1H-indazoles, which can afford the corresponding ortho-(arylsulfonylamino)benzonitriles under base catalysis, was obtained unexpectedly. Herein, the optimal reaction conditions were explored and the results showed that high temperature and aprotic polar solvent are favorable to the ring-opening reaction. Most of the substrates studied can provide the corresponding ring-opening products in moderate to good yields after stirring in DMSO with K₂CO₃ at 120 °C for 18 h, suggesting the excellent compatibility of functional groups and the broad substrate scope of this reaction. Furthermore, the control experiments implied that 1-arylsulfonyl-3-iodoindazoles go through an E2 elimination mechanism similar to Kemp elimination.

Graphical Abstract

Keywords:

• Kemp elimination
• 1-substituted 3-iodo-1H-indazoles
• ring opening
• ortho-(arylsulfonylamino)benzonitriles
• E2 elimination

Acknowledgments

The authors thank Alicia Glatfelter, PhD, from Liwen Bianji, Edanz Editing China (www.liwenbianji.cn/ac) for editing the English text of a draft of this manuscript.

Additional information

Funding

This work was financially supported by Shanghai Committee of Science and Technology of China [Nos. 15431902900 and 19431901800].