Substrate‐Guided Divergent Synthesis of Thiochromanes and Allyl Sulfides via a Mannich‐Type Reaction

We present a method for the selective synthesis of thiochromanes and allyl sulfides that is both metal‐ and oxidant‐free. This method uses 2‐methylquinoline or acetophenone, paraformaldehyde, and thiols as substrates. Varying the thiol substrates allows for the controlled synthesis of either thiochromanes or allyl sulfides. This protocol uses HCl as a promoter, providing an easy, efficient way to produce these sulfur‐containing compounds. Mechanistic studies suggest that the transformation proceeds via a Mannich‐type reaction pathway.