Ru(ii)-Catalysed synthesis of (1H)-isothiochromenes by oxidative coupling of benzylthioethers with internal alkynes.

The synthesis of 1H-isothiochromenes by oxidative coupling of benzyl(tert-butyl)thioethers with internal alkynes, catalysed by Ru(ii), has been achieved. The reaction occurs by S-directed C-H activation at the ortho position of the aryl ring, promoted by ruthenium, migratory insertion of the alkyne, 1,2-thio-Wittig rearrangement of the tert-butyl group and reductive elimination by C-S coupling between the resulting anionic sulfide and the vinylic carbon.