Stereoselective Allylstannane Addition for a Convergent Synthesis of a Complex Molecule.

A convergent methodology with 13 lineal steps for the synthesis of phormidolides B and C macrocyclic core is described. Stereoselective formation of the tetrahydrofuran (THF) core was achieved using a stereocontrolled allylation reaction. The key step of the synthesis is a (Z)-1,5-anti stereoselective allylstannane addition where a new stereocenter and a trisubstituted double bond are formed simultaneously. Finally, Shiina macrolactonization conditions improved the yield of the final cyclization.