Establishing the absolute configuration of the asbestinins: enantioselective total synthesis of 11-acetoxy-4-deoxyasbestinin D.

A highly stereoselective synthesis of 11-acetoxy-4-deoxyasbestinin D (1) has been completed in 26 linear steps. The synthesis hinges on a selective glycolate aldol addition to establish the C-2 stereocenter, a ring-closing metathesis reaction to complete the oxonene, and an intramolecular Diels-Alder cycloaddition to establish the relative configuration at C-1, C-10, and C-14. This initial total synthesis of an asbestinin also serves to confirm the absolute configuration of this subclass of the C-2-C-11-cyclized cembranoid natural products.