Photochemical Synthesis of α-Substituted Vinylazaarenes Enabled by Thia-Paternò–Büchi Reactions

The thia-Paternò-Büchi reaction represents a significant approach for accessing thio compounds, such as thia-cyclobutanes and the corresponding thiols generated upon ring-opening of thia-cyclobutanes. Herein, we report a novel paradigm of this classical reaction wherein thiols can undergo further elimination to form olefins. Consequently, under visible-light irradiation, 2-azaarenethiones react efficiently with various α-Bpin-substituted olefins, yielding synthetically valuable α-substituted vinylazaarenes in high yields. The substrate scope is exceptionally broad, enabling the incorporation of diverse aryl, alkyl, and azaarene substituents into the products. Furthermore, this method has been successfully demonstrated for the synthesis of azaarene-based three-substituted nonterminal olefins.