Palladium-Catalyzed Synthesis of Tetrahydrofurans from γ-Hydroxy Terminal Alkenes:  Scope, Limitations, and Stereoselectivity

A new, stereoselective synthesis of substituted tetrahydrofurans via Pd-catalyzed reactions of aryl and vinyl bromides with γ-hydroxy terminal alkenes is described. This transformation affords trans-2,5- and trans-2,3-disubstituted tetrahydrofurans with up to >20:1 dr. This methodology also provides access to bicyclic and spirocyclic tetrahydrofuran derivatives in good yield with 10−20:1 dr. The scope and limitations of these transformations are discussed in detail, as are the effect of substrate sterics and electronics on yield and stereoselectivity. A proposed mechanism of these transformations is presented along with a model that rationalizes the stereochemical outcome of the reactions.