| 摘要 |
PURPOSE:To produce the titled compound useful as an intermediate of perfumery and pharmaceuticals, economically, by carrying out the rearrangement of a 4- cyclopentenone compound, and reacting the resultant reaction mixture containing 2-cyclopentenone with a malonic acid ester without removing the catalyst from the system. CONSTITUTION:The 4-cyclopentenone compound of formula I (R is alkyl, alkenyl, cycloalkyl, substituted or unsubstituted aryl or aralkyl) is heated in the presence of 1,8-diaza-bicyclo(5,4.0)-undecene or its organic acid salt to effect the rearrangement to the 2-cyclopentenone compound of formula II. The obtained reaction mixture containing the 2-cyclopentenone compound is made to react with the malonic acid ester of formula III (R' is lower alkyl) in the presence of a basic catalyst such as sodium methylate, etc. to obtain the objective cyclopentanone derivative of formula IV (e.g. dimethyl-2-n-pentyl-3-oxo-cyclopentyl malonate). |
