A novel and efficient stereoselective synthesis of the southern part of pamamycin-607

Abstract

The C 1′C 11′ portion of the antibiotic pamamycin-607 was synthesized from the enantiomerically pure hydroxy acetate 3, readily available by enzymatic transesterification of the corresponding diol with vinylacetate. This synthesis entailed a series of stereoselective transformations: the absolute configurations of C 6′ and C 8′ were fixed by an aldol condensation followed by an anti-reduction of the resulting β-hydroxyketone. The configurations of the last two asymmetric centers C 2′ and C 3′ were controlled by a novel highly diastereoselective intramolecular cyclization catalyzed by fluoride ions.