(R)-Roche ester and (S)-glycidol as chirons, the synthesis involved a highly syn-selective Lewisacidcatalyzed 6-endo-trig cyclization for the construction of the dihydropyran subunit. The lactone segment was built through a tandem NaOMe conjugate addition-lactonization reaction, and further functionalized through a sequence consisting of iodination, I−Mg exchange, and hydroxymethylation. Other key steps in