19 steps in the longest linear sequence are required in the 27 step totalsynthesis of gephyronic acid. A key step is a diastereodifferentiating Mukaiyama aldol reaction of an aldehyde and an enolsilane (see picture, PG: protecting group). The strongly cytotoxic target compound is a structural relative of the polyketide tedanolide and was isolated from the myxobacterium Archangium gephyra.