Tuning Selectivity in the Visible-Light-Promoted Coupling of Thiols with Alkenes by EDA vs TOCO Complex Formation

The visible-light-promoted catalyst-free condition has been demonstrated for self-and cross-coupling reactions of thiols in an ambient atmosphere. Further, synthesis of beta-hydroxysulfides is accomplished under very mild conditions involving the formation of an electron donor-acceptor (EDA) complex between a disulfide and an alkene. However, the direct reaction of thiol with alkene via the formation of a thiol-oxygen co-oxidation (TOCO) complex failed to produce the desired compounds in high yields. The protocol was successful with several aryl and alkyl thiols for the formation of disulfides. However, the formation of beta-hydroxysulfides required an aromatic unit on the disulfide fragment, which supports the formation of the EDA complex during the course of the reaction. The approaches presented in this paper for the coupling reaction of thiols and the synthesis of beta- hydroxysulfides are unique and do not require toxic organic or metal catalysts.

Automated summary

This study demonstrates a visible-light-promoted catalyst-free condition for self-and cross-coupling reactions of thiols in an ambient atmosphere. It also accomplishes the synthesis of beta-hydroxysulfides under very mild conditions by forming an electron donor-acceptor (EDA) complex between a disulfide and an alkene. However, the direct reaction of thiol with alkene via the formation of a thiol-oxygen co-oxidation (TOCO) complex did not yield the desired compounds in high yields. The approaches presented in this paper for thiols coupling and beta-hydroxysulfides synthesis are unique and do not require toxic organic or metal catalysts.