ChemInform Abstract: Absolute Configuration and Synthesis of 2-Hydroxy-2-(1-hydroxyethyl)-3- methyl-γ-butyrolactone, a Presumed Pheromone of Ithomiine Butterflies.

Abstract

2-Hydroxy-2-(1-hydroxyethyl)-3-methyl-γ-butyrolactone (1) is a constituent of scent glands of male ithomiine butterflies. All diastereomers and the respective (3R)-enantiomers were synthesized by starting from rac- or (3S)-3-methyl-γ-butyrolactone 3. Their relative configurations were determined by difference NOE-NMR spectroscopy or by X-ray diffraction analysis. The absolute configuration of the natural product was determined by gas chromatography on a chiral stationary phase of the respective dioxolane derivatives. The natural lactone could be shown to be the (1′S,2S,3R)-enantiomer [(1′S,2S,3R)-1a, ithomiolide A]. In addition, the corresponding ketone, (2S,3R)-2-acetyl-2-hydroxy-3-methyl-γ-butyrolactone [(2S,3R)-5a, ithomiolide B], could be identified as a new natural product from Prittwitzia hymaenea.