Photoinduced Radical Relay Reaction of 2-Methylthiolated Phenylacetylenes/Alkynones Initiated by Electron Donor–Acceptor Complexes

A method was found to construct sulfur-containing five- and six-membered heterocyclic alkyl sulfonyl compounds by using visible light and free radicals activated and/or generated by EDA complexes/homolytic cleavage as initiators to stimulate the relay reaction of alkynes/alkynones. This method puts forward a new strategy to initiate alkyl sulfonation of alkynes/alkynones with only a catalytic amount of the initiator. This strategy of generating the initiator by EDA complex activation/homolytic cleavage provides a new idea for the following substances that must be excited.