[reaction: see text] Enantioselective synthesis of attenols A and B was accomplished by using diastereoselective hydroboration, Lindlar reduction, and acid-catalyzed acetal formation.
enantioselective synthesis of attenols A and B, cyclic polyethers of marine origin, was accomplished on a semigram scale by using diastereoselective hydroboration, coupling with lithium acetylide, Lindlar reduction and acid-catalyzed acetal formation. The configuration of the remaining undetermined spiro acetal carbon was unambiguously determined to be 11S using this ample supply of attenol A. The antitumor