AbstractTwo new enantioselective syntheses of the naphthopyranquinone antibiotic frenolicin B (1), of its enantiomer2, and of its diastereoisomers3and4were accomplished using two different routes from optically active β‐Hydroxy esters (R)‐ and (S)‐11and18.β‐Hydroxy esters (R)‐ and (S)‐11were prepared stereoselectively from optically active sulfenylacetates (S)‐ and (R)‐10, respectively (Scheme 2, Method A). Alternatively, compound18was obtained in excellent yield by enantioselective hydrogenation of the corresponding β‐keto ester17, using a chiral ruthenium‐complex catalyst (Scheme 3, Method B). Subsequently, compounds (S)‐11and18were transformed into frenolicinB (1).In analogy, Stereoisomers2–4were prepared from (S)