Two new enantioselectivesyntheses of the naphthopyranquinone antibiotic frenolicin B (1), of its enantiomer 2, and of its diastereoisomers 3 and 4 were accomplished using two different routes from optically active β-Hydroxy esters (R)- and (S)-11 and 18. β-Hydroxy esters (R)- and (S)-11 were prepared stereoselectivelyfrom optically active sulfenylacetates (S)- and (R)-10, respectively (Scheme 2,