The elucidation of the absolute configuration of (+)-abscisic acid (IX) was of considerable recent research intereet (l-7). In continuation of our previous work on the synthesis of the optically active grasshopper ketone (III) starting from an optically active ketone (I)(g), we have now accomplished the synthesis of the optically active dehydrovomifoliol t(S)-(+)-VIII)(9). This added another evidence favoring the absolute stereochemistry IX assigned for (+)-abscisic acid. The optically active ketone (I), [a];9 +36.6' (c-1.6, CHC13); CD(w0.22, MeOH)@] + 1,530, was converted to the enyne diacetate (II) as previously described (8). This was treated with LiAlH4 in THF to give 3S-hydroxy-S-ion01 (IV), which in turn was oxidized with 2,3-dichloro-5,6-dicyeno-p-benzoquinone (DDQ) in dioxane. The product was chromatographed (Al2O3) to give JS-hydrov-S-ionone (Va), [ajz2 -76.8' (c=l.OS, CHC13). in 44% yield (10,ll). Acetylation of the ketol (Va) with Ac20 in C5H5N gave in quantitative yield the acetate (Vb). Subsequent epoxidation with m-chloroperbenzoic acid in CHCl3 yielded two crystalline epoxides after chromatographic (SiOp) purification. The steric course of this type of reaction is known to give a cis-epoxide as a maJor and less strongly adsorbed product -2635