| 摘要 |
PURPOSE:To obtain the titled easily purifiable compound containing one of antipodes in excess of the other, by reacting 4-hydroxy-2-cyclopentenone with a lactone corresponding to the aimed compound at a specific reaction molar ratio in the presence of a specific catalyst. CONSTITUTION:4-Hydroxy-2-cyclopentenone is reacted with (1R,5S)-6,6-dimethyl- 4-hydroxy-3-oxabicyclo[3.1.0]hexan-2-one or an antipode thereof at 1.5-2:1molar ratio between the former and the latter in the presence of p-toluene (or benzenetoluene) sulfonic acid while being dehydrated in an axeotropic solvent by the azeotropic method to give (1R,5S)-6,6-dimethyl-3-oxa-4-(R)-[1(R)-4-oxo-2-cyclopentenyloxy]bicycl o[3.1.0]hexan-2-one of the formula or an antipode thereof useful as a raw material for prostaglandins in excess of the respective antipodes.
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