Visible-Light/Copper-Catalyzed Three-Component Synthesis of Unprotected β-Arylethylamines and β-Aryl Isothiocyanates via Thianthrenium Salts.

Unprotected β-arylethylamines and their derivatives serve as prominently featured structural units in biological molecules. However, most of the reactions reported to date focus on intramolecular and two-component reactions with certain limitations. There is an urgent need for an efficient strategy with a wider range of substrates compared to those of previous methods. Herein, a visible-light-promoted three-component reaction of arylthianthrenium salts, NH4SCN, and alkenes is reported using (rac-BINAP)Cu(MeCN)BF4 as a photoredox catalyst, which yields unprotected β-arylethylamines in the presence of a base, while β-aryl isothiocyanates are unexpectedly obtained under base-free conditions. Moreover, this protocol demonstrates broad substrate generality and a high functional group compatibility.