Synthesis of 1<i>H</i>-isothiochromenes by regioselective C–C and C–S bond formation of enaminothiones with alkynes under rhodium catalysis

The rhodium-catalyzed sulfur-directed C-H bond activation and tandem cyclization of enaminothiones with alkynes proceed efficiently. Most products of 1<i>H</i>-isothiochromenes with various substituents are achieved in good yields by regioselective C-C and C-S bond formation. This protocol has some advantages over the traditional methods in synthesizing 1<i>H</i>-isothiochromenes in terms of stable and easily available coupling substrates, simple and one-pot operation, step and atom economy, and highly unique sulfur-containing heterocyclic products.