Synthetic studies on nogalamycin congeners [2] 1,2 chiral synthesis of the cdef-ring system of nogalamycin

Abstract

The chiral synthesis of the (+)-naphthoquinone (4), the CDEF-ring system of nogalamycin congeners, has been accomplished following the synthetic scheme developed for the model (-)-DEF-ring system (3) in the preceding paper. This synthesis features (1) stereoselective construction of the C5'-asymmetric center by introducing the naphthalene moiety into the (-)-methyl ketone (5), the glycoside part, (2) regio-selective oxidation of the 1,4,5,8-tetramethoxynaphthalene moiety with cerium(III) ammonium nitrate , and (3) efficient formation of bicyclic acetal system.