Asymmetric synthesis of the tetrahydropyran ring, C32-C38 fragment, of phorboxazoles.

Organic letters

PubMedID: 15524477

Brinkmann Y, Carreño MC, Urbano A, Colobert F, Solladié G. Asymmetric synthesis of the tetrahydropyran ring, C32-C38 fragment, of phorboxazoles. Org Lett. 2004;6(23):4335-8.
The asymmetric synthesis of a model aldehyde (2R,6R)-2 and the C32-C38 fragment of phorboxazoles, (2R,4R,6R)-1, is described using a sulfoxide as chiral auxiliary. Key advances include the stereoselective reductions of beta-keto- or beta,gamma-diketosulfoxides, the acid-catalyzed cyclization of enantiopure sulfinyl hydroxy ketone precursors to the tetrahydropyran ring, and the Pummerer reaction on the pendant sulfoxide to create the formyl group.