Stereoselective synthesis of a fully protected C13–C23 fragment of tedanolide

The synthesis and biological evaluation of desepoxyisotedanolide and a comparison with desepoxytedanolide

The tedanolides are biologically active polyketides that exhibit a macrolactone constructed from a primary alcohol. Since polyketidal transformations only generate secondary alcohols, it has been hypothesized by Taylor that this unique lactone could arise from a postketidal transesterification. In order to probe this hypothesis and to investigate the biological profile of the putative precursor of all members of the tedanolide family, we embarked on the synthesis of desepoxyisotedanolide and its biological evaluation in comparison to desepoxytedanolide. The biological experiments unraveled a second target for desepoxytedanolide and provided evidence that the proposed transesterification indeed provides a survival advantage for the producing microorganism.

Stereochemically versatile synthesis of the C1-C12 fragment of tedanolide C

A flexible synthesis of the C1-C12 fragment of Tedanolide C has been accomplished in eight steps from 2-methyl-2,4-pentadienal. Asymmetric hydroformylation of a 1,3-diene allows for the late-stage generation of either C10 epimer with complete catalyst control. Diastereoselective addition of an isobutyryl β-ketoester dianion to an α,β-disubstituted chiral aldehyde sets the C5 stereochemistry while installing the geminal dimethyl unit. Differential protection of a syn-1,3-diol is performed as a highly efficient single-pot operation.