Synthesis of Sulfenylated Isocoumarins/Pyrones Mediated by Sulfoxide-Stabilized Sulfenium Electrophiles Derived from TCT-Sulfoxide.

The facile synthesis of methylthiolated and d3-methylthiolated isocoumarins and pyrones mediated by DMSO/DMSO-d6-stabilized methylsulfenium cation electrophiles derived from the TCT-DMSO/DMSO-d6 system via the interrupted Pummerer reaction has been developed. Herein, readily available trichlorotriazine (TCT), which is the most cost-efficient reagent for DMSO activation, was employed in an amount of 40 mol % relative to the substrate. Additionally, the sulfur sources were not confined to DMSO or DMSO-d6 alone, and both diethyl sulfoxide and phenyl methyl sulfoxide were also compatible, allowing the installation of methylthio, d3-methylthio, ethylthio, and phenylthio groups on the cyclization products.