Visible Light Mediated Photocatalyst Free C-S Cross Coupling: Domino Synthesis of Thiochromane Derivatives via Photoinduced Electron Transfer.

An efficient visible light mediated photocatalyst free C-S cross-coupling reaction has been developed for the synthesis of thiochromane derivatives through photoinduced electron transfer (PET). This methodology was further utilized for the synthesis of thiochroman-4-ol through intermolecular three-component cross-coupling reaction. The reaction proceeds via C-S bond formation through EDA complex/thioester cleavage/inter-or intramolecular -Michael addition followed by aldol reaction sequence. The EDA complex formation between aryl iodides and xanthate has been substantiated using spectroscopic experiments and DFT calculations.