Abstract A process for preparing cyclopentenolones in good yields which comprises treating a 4-hydroxy-4-R2-5-R1-2-cyclopentenone of the formula: <IMAGE> 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: <IMAGE> (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 DEG to 200 DEG C. to give the corresponding 2-R1-3-R2-4-hydroxy-2-cyclopentenone of the formula: <IMAGE> wherein R1 and R2 are each as defined above.
Inventors
👤 Kenji Saito
👤 Hiroshi Yamachika
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-07 17:26
CPC Classifications
C; C07; C07C; C07C45/00; C07C45/61; C07C45/67
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
121 words
A process for preparing cyclopentenolones which comprises treating a 4-hydroxy-4-R 2 -5-R 1 -2-cyclopentenone of the formula: ##STR13## wherein R 1 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: ##STR14## in which R 3 is hydrogen, methyl or halogen and R 2 is a hydrogen atom or a methyl group, provided that when R 2 is hydrogen, R 1 is neither α-methylallyl nor α-methylpropargyl, in an aqueous medium to give the corresponding 2-R 1 -3-R 2 -4-hydroxy-2-cyclopentenone of the formula: ##STR15## wherein R 1 and R 2 are each as defined above.
Claim 2
Dependent Claim
121 words
A process for preparing cyclopentenolones which comprises treating a 4-hydroxy-4-R 2 -5-R 1 -2-cyclopentenone of the formula: ##STR13## wherein R 1 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: ##STR14## in which R 3 is hydrogen, methyl or halogen and R 2 is a hydrogen atom or a methyl group, provided that when R 2 is hydrogen, R 1 is neither α-methylallyl nor α-methylpropargyl, in an aqueous medium to give the corresponding 2-R 1 -3-R 2 -4-hydroxy-2-cyclopentenone of the formula: ##STR15## wherein R 1 and R 2 are each as defined above.
Claim 3
Dependent Claim
20 words
The process according to claim 1, wherein the treatment is carried out at a temperature of 20° to 200° C.
Claim 4
Dependent Claim
20 words
The process according to claim 1, wherein the treatment is carried out at a temperature of 120° to 200° C.
Claim 5
Dependent Claim
19 words
The process according to claim 1, wherein the treatment is carried out in the presence of a metal salt.