Enantioselective synthesis of the 13-membered macrodiolide bartanol

Abstract

The enantioselective synthesis of the unusual 13-membered ring macrodiolide bartanol 7 from poly[(R)hydroxybutyrate] is described confirming the 6R,11R,13R configuration of the natural product. The use of a novel ylide 29 with a MEM-ester protecting group is developed to enable a mild, one-pot cleavage of both the acid and alcohol protecting groups in 30 prior to macrocyclisation to the bartanol framework. The outcome of a Wittig chain extension reaction on a mixture of lactols 19 and 22 using this ylide was found to be dependent on the solvent.