Process for preparing optically active 4-hydroxy-2-cyclipentenones.

摘要

A process for preparing an optically active 2-substituted or unsubstituted-4-hydroxy-2-cyclopentenone of the formula.
<Chemistry id="chema01" num="0001"><Image id="ia01" he="33" wi="38" file="IMGA0001.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry>wherein R is a hydrogen atom, an allyl group or a propargyl group, which comprises reacting the corresponding 2- substituted or unsubstituted-4-hydroxy-2-cyclopentenone of the formula:
<Chemistry id="chema02" num="0002"><Image id="ia02" he="32" wi="38" file="IMGA0002.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry>wherein R is defined above with a lactone chosen from (1R,5S)-6,6-Edimethyl-4-hydroxy-3-oxabicycto(3.1.0]hexan-2- one or (1S,5R)-6,6-dimethyl-4-hydroxy-3-oxabicyclo[3.1.0]-hexan-2-one in a molar ratio of 1.5 - 2 : 1 in the presence of p-toluenesulfonic acid or benzenesulfonic acid in the coexistence of an organic solvent under elimination of water as an azeotropic mixture with the organic solvent to obtain a reaction mixture comprising (1R,5S)-6,6-dimethyl-3-oxa-4(R)-[1(R)-4-oxo-2-substituted or unsubstituted-2-cyclo- pentenyloxy]bicyclo[3.1.0]hexan-2-one or (1S,5R)-6,6-dimethyl-3-oxa-4(S)-[1(S)-4-oxo-2-substituted or unsubstituted-2-cyclopentenyloxy]bicyclo[3.1.0]hexan-2-one of the formula:
<Chemistry id="chema03" num="0003"><Image id="ia03" he="49" wi="57" file="IMGA0003.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry>

wherein R is as defined above, of which either one isomer is contained in a considerably larger amount than the other isomer, separating the isomer having the larger content from the reaction mixture and hydrolyzing the separated isomer to give the optically active 2-substituted or unsubstituted-4-hydroxy-2-cyclopentenone.