Synthesis of the C1-C13 tetraenoate subunit of the chivosazoles.

Using a combination of asymmetric vinylogous Mukaiyama aldol and Stille cross-coupling reactions, an advanced polyene fragment of the chivosazoles was prepared in a highly stereocontrolled manner. This key C1-C13 pentaene subunit, featuring the conjugated (2E,4Z,6E,8Z)-tetraenoate motif and anti-configured C10 and C11 stereocenters of the chivosazoles, terminates in a (Z)-vinyl bromide for the planned cross-coupling to a northern hemisphere fragment.