Bro̷nsted Acid-Catalyzed Reduction of Furans

Bioderived furans play a pivotal role in advancing defossilized chemical pathways. The complete reduction of furans currently relies on impractical metal-catalyzed hydrogenations at high pressures and temperatures. In addition, the Birch reduction of unbiased furans to 2,5-dihydrofurans remains an unsolved synthetic challenge. Herein, we report a mild Bro̷nsted acid-catalyzed reduction of furans to 2,5-dihydro- and/or tetrahydrofuran derivatives using silanes as reducing agents. In particular, the first formal Birch reduction of furan itself is achieved. Mechanistic investigations reveal an intricate behavior of HFIP as the crucial solvent, preventing the intrinsic polymerization behavior of furans under acidic conditions and introducing additional driving force by specific product binding.