Synthesis of 4-Sulfenyl-Isocoumarins via Thio-Annulation of 2-Alkynyl-benzonate with RSCl: In Situ Prepared by Disulfides and HCl/HNO3

We have developed a novel and metal-free method to construct the derivatives of 4-sulfenyl isocoumarins via thio-annulation of 2-alkynyl benzoates with sulfenyl chlorides which is in situ prepared by disulfides and HCl/HNO3. The reaction shows high functional group tolerance and can be scaled up to the gram-scale with less loss in yield. Both sulfide groups of the disulfide reagent were used in the reaction.