Synthesis of 2,6- trans -Tetrahydropyrans Using a Palladium-Catalyzed Oxidative Heck Redox-Relay Strategy.

The C-aryl-tetrahydropyran motif is prevalent in nature in a number of natural products with biological activity; however, this challenging architecture still requires novel synthetic approaches. We demonstrate the application of a stereoselective Heck redox-relay strategy for the synthesis of functionalized 2,6- trans -tetrahydropyrans in excellent selectivity in a single step from an enantiopure dihydropyranyl alcohol, proceeding through a novel exo -cyclic migration. The strategy has also been applied to the total synthesis of a trans -epimer of the natural product centrolobine in excellent yield and stereoselectivity.