Efficient synthesis of dihydronaphthalenes via cerium-catalyzed annulation of 1-alkoxy substituted 1H-isochromenes with cinnamic acids

Dihydronaphthalenes play a crucial role in bioactive natural products and new drug discovery, and efficient and economic strategies to build them are needed. Herein, we disclose a highly efficient method to prepare dihydronaphthalenes via a cerium-catalyzed cycloaddition of 1H-isochromenes with cinnamic acids. This newly developed method not only features a broad and low-cost substrate scope and mild conditions but also exhibits very high functional group tolerance, including hydroxyl, borate ester and ester group substituents. In addition, the practicality of this general strategy is demonstrated by gram-scale reactions and derivatizations, and all of the reactions proceed smoothly to afford the desired compounds in excellent yields.