Enantiomerically pure (2R, 3S)-(−)-and (2S, 3R)-(+)-2, 3-epoxy-2-methylbutanoic acids 7 and 8 were prepared from 2-methyl-2-butenoic acid 1 (tiglic acid). They were characterized by spectroscopic and optical activity data and their absolute configuration was determined by chemical correlation with (R)-(+)-and (S)-(−)-2-methyl-1, 2-butanediols. The corresponding methyl (16 and 17), menthyl (3 and 4), and 9α-angeloyloxy-1-oxolongipin- ...