Synthetic efforts toward the synthesis of octalactins

Octalactin B was synthesized from the commercially available methyl-3-butenoate and isobutyraldehyde, using enantioselective allyl- and crotyltitanations to control the stereogenic centers at C3, C4, C7, C8, and C13. Moreover, the two other key-step reactions are a cross-metathesis reaction and a lactonization, using the effective anhydride MNBA, to build up the eight-membered ring lactone.