A Synthetic Approach to the Furanocembrane Carbon Skeleton by a Regioselective Bromine-Magnesium Exchange Reaction

The dibromofuran 6 was prepared in four steps from dibromofurfural 3 in 73% yield. It was regioselectively metalated by a bromine-magnesium exchange reaction and was added to aldehyde 7. Alcohol 8 was obtained by this key step in 75% yield. Further functionalization reactions led to the precursors 17-19 for an intramolecular Nozaki-Hiyama coupling. The ringclosing Nozaki-Hiyama protocol was successfully implemented in the synthesis of the macrocyclic propargylic alcohol 20.