Synthesis of Fused-Ring and Attached-Ring bis-Tetrahydrofurans via Pd-Catalyzed Carboetherification

A five step-synthesis of fused bis-tetrahydrofurans and attached bis-tetrahydrofurans from butadiene diepoxide is described. Two sequential Pd-catalyzed carboetherification reactions between protected 1,2-diols and aryl/alkenyl bromides, each of which form both a C-O bond and a C-C bond, are used to generate the heterocyclic rings with >20:1 dr. Installation of different R-1 and R-2 groups is achieved in a straightforward fashion through use of different aryl or alkenyl bromide coupling partners.