CuCl2-promoted decomposition of sulfonyl hydrazides for the synthesis of thiosulfonates

Sulfonyl hydrazides recently received much attention as reagents for the introduction of sulfur-containing functional groups into organic compounds, because both sulfonyl and sulfenyl sources could be generated by the oxidation and decomposition of the sulfonyl hydrazides, respectively. However, the transformations of sulfonyl hydrazides into thiosulfonates, which could be produced by the reaction between sulfonyl and sulfenyl sources, have been less investigated. In this manuscript, we describe CuCl2-promoted selective synthesis of thiosulfonates from sulfonyl hydrazides. A variety of thiosulfonates were produced in moderate to good yields. The mechanism involving radical intermediates such as sulfonyl radical and thiyl radical was proposed on the basis of the previously reported references and mechanistic investigations. In addition, quantum chemical simulations revealed that Cu-promoted decomposition of sulfonyl hydrazides is thermodynamically viable in the developed conditions. (C) 2020 Elsevier Ltd. All rights reserved.