An efficient enantioselective synthesis of the acyl side chain of polyoxypeptins

An enantioselective synthesis of the acyl side-chain 3 of polyoxypeptins 1 and 2 was achieved by the Sharpless AE, with subsequent regioselective opening of the epoxyalcohol using a Grignard reagent in the presence of CuI, and an aldol condensation using Seebachʹs ester. The method reported has the advantage of a concise route and excellent enantiomeric purity, as well as starting from readily available chemical substrates and the use of inexpensive reagents.