Process for preparing cyclopentenolones.

摘要

A process is described for preparing cyclopentenolones in good yields which comprises treating a 4-hydroxy-4-R2-5-R1-2-cyclopentenone of the formula: <CHEM> wherein R1 is an alkyl group having not more than 6 carbon atoms, an alkenyl group having not more than 6 carbon atoms, an alkynyl group having not more than 6 carbon atoms or a group of the formula: <CHEM> (in which R3 is hydrogen, methyl or halogen) and R2 is a hydrogen atom or a methyl group, provided that when R2 is hydrogen, R1 is neither alpha -methylallyl nor alpha -methylpropargyl, in an aqueous medium in the presence or absence of a metal salt at a temperature of 20 to 200 DEG C to give the corresponding 2-R1-3-R2-4-hydroxy-2-cyclopentenone of the formula: <CHEM> wherein R1 and R2 are each as defined above. l