Generation of Sulfonyl Radicals from Aryldiazonium Tetrafluoroborates and Sulfur Dioxide: The Synthesis of 3-Sulfonated Coumarins.
A catalyst-free approach for the generation of sulfonyl radicals from aryldiazonium tetrafluoroborates in the presence of DABCO⋅(SO2 )2 is realized. The combination of aryldiazonium tetrafluoroborates, DABCO⋅(SO2 )2 , and aryl propiolates affords 3-sulfonated coumarins in good to excellent yields. This tandem reaction process involves radical addition, spirocyclization, and 1,2-migration of esters. Additionally, the in situ diazotization of a number of anilines allows the directional synthesis of desired 3-sulfonated coumarins in a one-pot, two-step process.
Department of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433, China.
Danqing
D
Zheng
Department of Chemistry Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA-, 30302, USA.
Jiyao
J
Yu
Department of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433, China. jie_wu@fudan.edu.cn.|State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China. jie_wu@fudan.edu.cn.
Jie
J
Wu
diazo compounds; heterocycles; radicals; sulfur; synthetic methods