An efficient and stereoselective construction of the C(9)–C(17) dihydropyran segment of swinholides A–C via a novel reductive cleavage of an epoxy aldehyde

An efficient and highly stereoselective construction of the C(9)–C(17) dihydropyran segment of swinholides A–C, which involves a novel reductive cleavage of an epoxy aldehyde by an organoselenium reagent and the intramolecular conjugate addition of an acetal alkoxide anion of δ-hydroxy-α,β-unsaturated ester as the key steps, is described.