A highly diastereoselective synthesis of N-acetyl dihydrotetrafibricin methyl ester (34) is described. The synthesis features three enantioselective double allylboration reactions and an intramolecular hydrosilylation/Fleming-Tamao oxidation sequence to establish seven of the hydroxy-bearing stereocenters of 34. Especially noteworthy is the fragment-assembly double allyboration reaction of 2 and 7 using reagent 3, which provides the advanced intermediate 6 with >20:1 diastereoselectivity.