Thioacetalation and Multi-Component Thiomethylative Friedel-Crafts Arylation Using BF₃SMe₂

Herein, a method for thioacetalation using BF₃SMe₂ is presented. The method allows for convenient and odor-free transformation of aldehydes to methyl-dithioacetals, a simple but sparsely reported structural moiety, in good yields with a diverse set of aromatic aldehydes. In addition, a thiomethylative Friedel-Crafts reaction was discovered, affording thiomethylated diarylmethanes in good to excellent yields. The resulting diarylmethane core is of interest as it is found in many biologically active compounds, and its utility is further demonstrated as a novel precursor to unsymmetrical triarylmethanes. This work also highlights the usefulness and the synthetic capabilities of the readily available reagent BF₃SMe₂ beyond its reactivity profile as a dealkylation reagent.