Díaz Sandra, Cuesta Javier, González Asensio, Bonjoch Josep
Laboratori de Química Orgànica, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028-Barcelona, Spain.
J Org Chem. 2003 Sep 19;68(19):7400-6. doi: 10.1021/jo034838r.
The total synthesis of the enantiomer of the marine sponge diterpenoid nakamurol A and determination of the absolute configuration of this natural product are reported. This first synthetic entry to thelepogane-type diterpenoids involves the use of the bicyclic enone (-)-3, which after a tandem difunctionalization process and elongation of the side chain leads to the formation of the ketone (-)-13. From (-)-13, two approaches to ent-nakamurol A (1) are reported: the straightforward but nonselective way, by reaction with vinylmagnesium bromide, and a longer but stereocontrolled route, through the primary allylic alcohol 20, which is submitted to a Sharpless epoxidation followed by a tellurium-promoted reductive-epoxide ring-opening cascade reaction.
