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Reaction of (S) (-)-α-tosyloxy acid ((S)(-)-3) with methyl- or n-butyllithium was found to afford (R)(+)-vicinal (vic)-diol ((R)(+)-4) in an excellent yield with almost full inversion. On the other hand, when (S)(-)-α-hydroxy acid ester ((S)(-)-5) was allowed to react with methyl- or n-butyllithium, (S)(-)-vic-diol ((S)(-)-4) was obtained in an excellent yield with full retention. Since (S)(-)-3 and (S)(-)-5 are both derivable from L-phenylalanine (L-1), it has become possible to obtain an enantiomeric pair of vic-diols from L-1. Plausible formation mechanism for (R)(+)-4 from (S)(-)-3 was proposed. The utility of optically active vic-diols in natural product synthesis was also visualized by preparing the novel synthetic intermediate for epoxyterpene synthesis ((S)(-)-6) from (S)(-)-4a.