Facile formation of tetrahydrofurans with multiple chiral centers using double iodoetherification of σ-symmetric diene acetals: short asymmetric total synthesis of rubrenolide and rubrynolide

A novel double intramolecular iodoetherification of σ-symmetric diene acetals from (R,R)-hydrobenzoin occurred in highly diastereoselective manners to give tetrahydrofuran moieties with multiple chiral centers in a one-pot operation. The chemoselective discrimination of the two iodomethyl functions in the products was attained in various reactions. The reaction was applied to the concise asymmetric syntheses of rubrenolide and rubrynolide, in which the unit from the chiral auxiliary worked as a template to achieve the chemoselectivity and as the protecting group of the hydroxyl function.