Cascade Trisulfur Radical Anion (S<sub>3</sub><sup>•–</sup>) Addition/Electron Detosylation Process for the Synthesis of 1,2,3-Thiadiazoles and Isothiazoles
作者:Bei-Bei Liu、Hui-Wen Bai、Huan Liu、Shun-Yi Wang、Shun-Jun Ji
DOI:10.1021/acs.joc.8b01450
日期:2018.9.7
Trisulfur radical anion (S3•–) mediated reactions with in situ formed azoalkenes and α,β-usaturated N-sulfonylimines for the construction of 1,2,3-thiadiazoles and isothiazoles has been developed. S3•– is in situ generated from potassium sulfide in DMF. These two approaches provide a new, safe, and simple way to construct 4-subsituted 1,2,3-thiadiazoles, 5-subsituted 1,2,3-thiadiazoles, and isothiazole
A bioinspired two-component redox organocatalyst system using 1,10-bridged flavinium and NH4I was developed to perform environmentally friendly aerobic oxidative ring formation of 1,2,3-thiadiazoles from N-tosylhydrazones and sulfur. The redox organocatalysis of the flavinium promoted the iodine-catalyzed system without the use of any sacrificial reagents, except for environmentally benign molecular
A metal‐ and oxidant‐free electrochemical method for synthesizing 1,2,3‐thiadiazoles by inserting elementsulfur into N‐tosylhydrazones is reported. This electrochemical transformation engages electrons as reagents to achieve redox processes, and avoid excess oxidants. The cyclic voltammograms are examined to explore the mechanism of this electrolysis reaction.
The efficient synthesis of γ-thiapyrones by a base-mediated Diels–Alder/retro-Diels–Alder reaction of α-pyrones with 5-H-1,2,3-thiadiazoles is reported herein. Thioketenes in situ generated from thiadiazoles as electron-poor dienophile and electron-rich 4-hydroxy-2-pyrones as dienes are conjunctively transformed into a series of γ-thiapyrones with broad functional group compatibility in good to excellent