Gold- and Acid-Catalyzed Synthesis of Tetrahydropyrans and Tetrahydrofurans

Significance

Allenes serve as highly reactive functional groups for the synthesis of complex molecules. The authors present two modes of activation for tethered allenes. Using gold catalysis, fused bicyclic heterocycles are produced. Alternatively Brønsted acid catalysis produces complex tetrahydrofuran spirocycles and tetrahydropyrans with excellent diastereoselectivity.