Enantiodivergent Total Syntheses of Nanaomycins and Their Enantiomers, Kalafungins

The first, enantiospecific total syntheses of pyranonaphthoquinone antibiotics, nanaomycins D and A, and their enantiomers, kalafungin and 4-deoxykalafunginic acid are described by an “enantiodivergent” strategy from a common optically active intermediate, (1S,3RS,4S)-3,4-dihydro-5,9,10-trimethoxy-1-methyl-1H-naphtho[2,3-c]pyran-3,4-diol, which has been derived from l-rhamnose via condensation of 4-methoxy-3(phenylsulfonyl)-1(3H)-isobenzofuranone and methyl 3,4,6-trideoxy-α-l-glycero-hex-3-enopyranosid-2-ulose.