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Updated: Jul 16, 2026

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
Control of the regioselectivity of sulfonamidyl radical cyclization by vinylic halogen substitution
Hongjian Lu1, Qian Chen, Chaozhong Li
1Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai, 200032, P. R. China.
Abstract:
The radical cyclization reactions of unsaturated sulfonamides were investigated. The photolysis of N-(4-halo-4-pentenyl)sulfonamides (X=I, Br, or Cl) with (diacetoxyiodo)benzene (DIB) and iodine at room temperature afforded exclusively the corresponding piperidines in 73-98% yield via 6-endo radical cyclization. On the other hand, the reactions of N-(5-halo-4-pentenyl)sulfonamides with DIB/I2 led to the only formation of the pyrrolidine products in 84-99% yield via 5-exo radical cyclization. The vinylic halogen substitution not only successfully inhibits the competing ionic iodocyclization process to allow the radical cyclization to proceed smoothly but also shows a remarkable effect in controlling the regioselectivity of cyclization.
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