A NOVEL AND EFFICIENT STEREOSELECTIVE SYNTHESIS OF THE SOUTHERN PART OF PAMAMYCIN-607

The C1'C11' portion of the antibiotic pamamycin-607 Was synthesized fr om the enantiomerically pure hydroxy acetate 3, readily available by e nzymatic transesterification of the corresponding diol with vinylaceta te. This synthesis entailed a series of stereoselective transformation s: the absolute configurations of C-6' and C-8' were fixed by an aldol condensation followed by an anti-reduction of the resulting beta-hydr oxyketone. The configurations of the last two asymmetric centers C-2' and C-3' were controlled by a novel highly diastereoselective intramol ecular cyclization catalyzed by fluoride ions. (C) 1997 Elsevier Scien ce Ltd.