Total syntheses of both enantiomers of amphirionin 4: A chemoenzymatic based strategy for functionalized tetrahydrofurans.

The total syntheses of (-)-amphirionin-4 and (+)-amphirionin-4 have been achieved in a convergent and enantioselective manner. The tetrahydrofuranol cores of amphirionin-4 were constructed in optically active form by enzymatic resolution of racemic cis-3-hydroxy-5-methyldihydrofuran-2(3H)-one. The polyene side chain was efficiently synthesized using Stille coupling. The remote C8-stereocenter was constructed using the Nozaki-Hiyama-Kishi coupling reaction. A detailed 1H-NMR studies of Mosher esters of (-)-amphirionin-4 and (+)-amphirionin-4 were carried out to support the assignment of the absolute configurations of C-4 and C-8 asymmetric centers of amphirionin-4.