Synthesis of desepoxyisotedanolide : a proposed biosynthetic precursor of the marine polyketide tedanolide and application of Kiyooka aldol reaction to generate tertiary alcohols stereoselectively Tedanolide isotedanolide natural product total synthesis polyketides macrolactone isomerization Kiyooka aldol. Tedanolid Isotedanolid Naturstoffe Totalsynthese Polyketid Makrolacton Isomerisierung