A New Synthesis of Tetrahydrofuran Fragment of Amphidinolides X and Y

A new synthesis of the tetrasubstituted tetrahydrofuran fragment of the marine secondary metabolites amphidinolides X and Y is described. The oxygenated chiral quaternary carbon was assembled by asymmetric dihydroxylation in high enantioselec­tivity and the tetrahydrofuran ring was constructed by an acid-catalyzed 5-endo ring-opening cyclization of the epoxide possessing a vinyl moiety.