A macrolactonisation approach to the cembrane carbocycle of bielschowskysin

By judicious choice of a conformationally constraining unit to predispose cyclisation to a 15-membered ring, we present a straightforward strategy to a cembranolide precursor of bielschowskysin by the Sonogashira coupling of two readily prepared fragments (from d-glucose and l-malic acid) followed by a facile β-acylketene macrolactonisation reaction.