Synthesis of the C1–C9, C11–C19 Pyran Core and C19–C24 Fragments­ of Macrolactin 3

Abstract We describe herein an efficient synthesis of the C1–C9, C11–C19 pyran moiety and C18–C24 core fragments of macrolactin 3. The prominent features of this work include construction of the Z-double bond of the 1,3-(Z,E)-diene system utilizing Horner–Wadsworth–Emmons­ reaction under Still–Gennari conditions. A Sharpless asymmetric epoxidation and subsequent epoxide opening under BF3·OEt2 conditions were applied to generate the stereogenic centers at C15 and C16, oxa-Michael addition and Jacobsen resolution facilitate the synthesis of the fragments.