5870-63-3

Basic information

• Product Name: 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE
• Synonyms: 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE;3-hydroxy-2-methylcyclopent-2-en-1-one
• CAS NO: 5870-63-3
• Molecular Formula: C₆H₈O₂
• Molecular Weight: 112.12652
• Mol File: 5870-63-3.mol
• Article Data: 2

Chemical Properties

• Melting Point: 213-215 °C(Solv: ethanol (64-17-5))
• Boiling Point: 212.2°Cat760mmHg
• Flash Point: 84.4°C
• Appearance: /
• Density: 1.225g/cm³
• PKA: 4.82±0.30(Predicted)
• CAS DataBase Reference: 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE(CAS DataBase Reference)
• NIST Chemistry Reference: 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE(5870-63-3)
• EPA Substance Registry System: 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE(5870-63-3)

Safety Data

• Hazardous Substances Data: 5870-63-3(Hazardous Substances Data)

Usage

General Description

3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE, also known as 3-Methyl-3-hydroxy-cyclopent-2-en-1-one, is a chemical compound with the molecular formula C6H8O2. It is a pale yellow liquid with a floral, herbal, and sweet odor. This chemical is commonly used as a flavoring substance in the food and beverage industry, as well as an intermediate for the synthesis of other organic compounds. It is also utilized in the production of fragrances, perfumes, and cosmetics due to its aromatic properties. Additionally, 3-HYDROXY-2-METHYL-CYCLOPENT-2-ENONE has some potential applications in the pharmaceutical and chemical research fields.

Synthetic route

2-methylcyclopentane-1,3-dione ethylene glycol monoacetal (54972-03-1) → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions	Yield
With hydrogenchloride In tetrahydrofuran; water for 10h;	71%

2-(1-ethoxy-ethyl)-2-hydroxy-cyclobutanone → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions	Yield
With Amberlyst 15; trifluoroacetic acid for 10h; Heating;	0.088 g

cyclopent-2-enone (930-30-3) → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions

Yield

Multi-step reaction with 5 steps 1.1: N,N,N,N,N,N-hexamethylphosphoric triamide; methyllithium / diethyl ether / 0.5 h / 0 °C / Inert atmosphere 1.2: 1 h / -78 °C / Inert atmosphere 1.3: 3 h / -78 - 20 °C / Inert atmosphere 2.1: toluene-4-sulfonic acid / benzene / 6 h / Reflux; Dean-Stark 3.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.33 h / Inert atmosphere 3.2: 20 h 4.1: tetrapropylammonium perruthennate; 4-methylmorpholine N-oxide / dichloromethane / 0.5 h / Molecular sieve; Inert atmosphere 5.1: hydrogenchloride / tetrahydrofuran; water / 10 h View Scheme

trans-2-methyl-3-(pentamethyldisilan-1-yl)cyclopentan-1-one → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions	Yield
Multi-step reaction with 4 steps 1.1: toluene-4-sulfonic acid / benzene / 6 h / Reflux; Dean-Stark 2.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.33 h / Inert atmosphere 2.2: 20 h 3.1: tetrapropylammonium perruthennate; 4-methylmorpholine N-oxide / dichloromethane / 0.5 h / Molecular sieve; Inert atmosphere 4.1: hydrogenchloride / tetrahydrofuran; water / 10 h View Scheme

1,1,1,2,2-pentamethyl-2-[trans-6-methyl-1,4-dioxaspiro[4,4]-nonan-7-yl]disilane → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions	Yield
Multi-step reaction with 3 steps 1.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 0.33 h / Inert atmosphere 1.2: 20 h 2.1: tetrapropylammonium perruthennate; 4-methylmorpholine N-oxide / dichloromethane / 0.5 h / Molecular sieve; Inert atmosphere 3.1: hydrogenchloride / tetrahydrofuran; water / 10 h View Scheme

trans-6-methyl-1,4-dioxaspiro[4.4]nonan-7-ol → 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3)

Conditions	Yield
Multi-step reaction with 2 steps 1: tetrapropylammonium perruthennate; 4-methylmorpholine N-oxide / dichloromethane / 0.5 h / Molecular sieve; Inert atmosphere 2: hydrogenchloride / tetrahydrofuran; water / 10 h View Scheme

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + orthoformic acid triethyl ester (122-51-0) → 2-Methylcyclopent-1,3-dione monoethyl enol ether (25112-86-1)

Conditions	Yield
With sulfuric acid In ethanol	98%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-chloro-2-methylcyclopent-2-en-1-one (35173-23-0)

Conditions	Yield
With diethyl(trichloromethyl)phosphine In dichloromethane for 12h; Ambient temperature;	92%
With tetrachloromethane; triphenylphosphine
With oxalyl dichloride In N,N-dimethyl-formamide

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 4,5-dioxohexanoic acid (89533-82-4)

Conditions	Yield
With oxygen; copper(II) perchlorate In acetonitrile for 12h; Ambient temperature;	92%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + benzylamine (100-46-9) → 3-(benzylamino)-2-methylcyclopent-2-en-1-one (134622-65-4)

Conditions	Yield
With toluene-4-sulfonic acid In toluene for 10h; Heating;	92%
With toluene-4-sulfonic acid In toluene Heating;	92%

N-(phenylthio)succinimide (14204-24-1) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 2-methyl-2-(phenylthio)-1,3-cyclopentanedione (72302-65-9)

Conditions	Yield
With triethylamine In benzene for 2h; Heating;	90%

hexan-1-amine (111-26-2) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-Hexylamino-2-methyl-cyclopent-2-enone (183674-19-3)

Conditions	Yield
With toluene-4-sulfonic acid In toluene Heating;	90%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + 1-aminopent-3-yne (91640-80-1) → C11H15NO

Conditions	Yield
With toluene-4-sulfonic acid In diethyl ether; toluene at 120℃; for 20h; Dean-Stark;	87%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-iodo-2-methyl-2-cyclopentenone (56778-49-5)

Conditions	Yield
With iodine; triethylamine; triphenylphosphine In acetonitrile for 12h; Reflux; Inert atmosphere;	87%

methanol (67-56-1) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-methoxy-2-methylcyclopent-2-enone (3883-56-5) + 2-methyl-3-phenylsulfanyl-cyclopent-2-enone (82909-44-2)

Conditions	Yield
With camphor-10-sulfonic acid; thiophenol at 20℃; for 96h;	A 10% B 78%

pent-3-yn-1-ol (10229-10-4) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → C11H14O2

Conditions	Yield
With toluene-4-sulfonic acid In toluene at 130℃; for 20h; Dean-Stark;	77%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + thiophenol (108-98-5) → 2-methyl-3-phenylsulfanyl-cyclopent-2-enone (82909-44-2)

Conditions	Yield
With camphor-10-sulfonic acid In methanol at 50℃; for 21h;	76%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + methyl vinyl ketone (78-94-4) → 2-methyl-2-(3-oxobutyl)-1,3-cyclopentanedione (25112-78-1)

Conditions	Yield
at 150℃; for 3h;	65%
With acetic acid In water at 70℃; Darkness; Inert atmosphere;

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + δ-Phenylselenenylbutanol (117901-60-7) → 3-(4-phenylselenobutanoxy)-2-methylcyclopent-2-en-1-one (118824-28-5)

Conditions	Yield
With toluene-4-sulfonic acid In benzene for 9h; Heating;	53%
With toluene-4-sulfonic acid In benzene Dean-Stark conditions;	53%

pyrrolidine (123-75-1) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 2-methyl-3-(1-pyrrolidinyl)-2-cyclopenten-1-one (3335-02-2)

Conditions	Yield
With acetic acid In ethanol for 4h; Heating;	5%

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-Bromo-2-methylcyclopent-2-en-1-one (56671-87-5)

Conditions	Yield
With carbon tetrabromide; triphenylphosphine In chloroform

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + ethyl 2-bromomethyl-2-propenoate (17435-72-2) → 2-(1-Methyl-2,5-dioxo-cyclopentylmethyl)-acrylic acid ethyl ester (53696-39-2)

Conditions	Yield
With potassium carbonate In acetone

methanol (67-56-1) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-methoxy-2-methylcyclopent-2-enone (3883-56-5)

Conditions	Yield
With toluene-4-sulfonic acid In benzene

ethanol (64-17-5) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 2-Methylcyclopent-1,3-dione monoethyl enol ether (25112-86-1)

Conditions	Yield
With toluene-4-sulfonic acid In benzene

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + (3-bromopropyl)(phenyl)selane (118824-31-0) → 3-(3-phenylselenopropanoxy)-2-methylcyclopent-2-en-1-one (118824-29-6)

Conditions	Yield
With sodium hydride 1) DMF, 0 deg C - room temperature, 20 min, 2) 70 deg C, 3 h; Yield given. Multistep reaction;
With sodium hydride DMF; Yield given. Multistep reaction;

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + 1-bromo-4-phenylselenobutane (118824-39-8) → 3-(4-phenylselenobutanoxy)-2-methylcyclopent-2-en-1-one (118824-28-5)

Conditions	Yield
With sodium hydride 1) DMF, 0 deg C - room temperature, 20 min, 2) 70 deg C, 4 h; Yield given. Multistep reaction;
With sodium hydride DMF; Yield given. Multistep reaction;

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + ethyl iodide (75-03-6) → 2-Ethyl-2-methyl-1,3-cyclopentanedione (25112-87-2)

Conditions	Yield
With potassium hydroxide

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + methyl iodide (74-88-4) → 2,2-dimethylcyclopentane-1,3-dione (3883-58-7)

Conditions	Yield
With potassium hydroxide

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + 2-(chloromethyl)-6-methoxy-4-(1-methylethyl)-1,2-benzisothiazol-3(2H)-one 1,1-dioxide (142577-03-5) → 4-Isopropyl-6-methoxy-2-(2-methyl-3-oxo-cyclopent-1-enyloxymethyl)-1,1-dioxo-1,2-dihydro-1λ6-benzo[d]isothiazol-3-one

Conditions	Yield
With sodium hydride 1.) DMF, RT, 30 min, 2.) DMF, RT, 144 h; Yield given. Multistep reaction;

diazomethane (186581-53-3, 908094-01-9) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 3-methoxy-2-methylcyclopent-2-enone (3883-56-5)

Conditions	Yield
In tetrahydrofuran; diethyl ether

3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) + aniline (62-53-3) → 4-oxo-5-(phenyl-hydrazono)-hexanoic acid

Conditions	Yield
With hydrogenchloride; sodium acetate; sodium nitrite 1) H2O, 0 deg C, 15 min, 2) H2O; Yield given. Multistep reaction;

Nonafluorobutanesulfonyl fluoride (375-72-4) + 3-hydroxy-2-methyl-2-cyclopenten-1-one (5870-63-3) → 2-methyl-3-(perfluoro-1-butanesulfonyloxy)-2-cyclopenten-1-one

Conditions	Yield
With sodium hydride 1.) DMF, room temperature (4 h), 45 deg C (45 min), 2.) DMF, room temperature, 3.5 h; Yield given; Multistep reaction;

Upstream product

• 54972-03-1 2-methylcyclopentane-1,3-dione ethylene glycol monoacetal 
• 930-30-3 cyclopent-2-enone 

Downstream Products

• 183674-23-9 N-benzyl-N-(2-methyl-3-oxocyclopent-1-enyl)pent-4-enamide 
• 1909-79-1 2-methyl-2-cyclopenten-1-one-3-carboxylic acid 
• 17553-86-5 (S)-Halos-Parish ketone 
• 33879-04-8 (+)-(3aS,7aS)-2,3,3a,4,7,7a-hexahydro-3a-hydroxy-7a-methyl-1H-indene-1,5(6H)-dione 
• 93676-89-2 2-<(phenylsulfinyl)methyl>-1,3-cyclopentanedione 
• 175469-20-2 N-benzyl,N-(3-oxo-cyclopent-1-enyl)-2-diallylaminoacetamide 
• 152496-58-7 N-benzyl,N-(2-methyl-3-oxo-cyclopent-1-enyl)-2-methoxyacetamide 
• 4608-44-0 2,3-dimethyl-3-(p-tolyl)cyclopentan-1-one 
• 54158-61-1 2-methyl-3-(4-methylphenyl)-2-cyclopentenone 
• 20935-29-9 2-methyl-3-[4-(methoxy)phenyl]cyclopent-2-ene-1-one 
• 82909-44-2 2-methyl-3-phenylsulfanyl-cyclopent-2-enone 
• 25112-86-1 2-Methylcyclopent-1,3-dione monoethyl enol ether 
• 134622-65-4 3-(benzylamino)-2-methylcyclopent-2-en-1-one 
• 3883-56-5 3-methoxy-2-methylcyclopent-2-enone 

Relevant articles and documents

Conversion of cycloalk-2-enones into 2-methylcycloalkane-1,3-diones - Assessment of various Tamao-Fleming procedures and mechanistic insight into the use of the Me3SiMe2Si unit

Conjugate addition of Me3SiMe2SiLi to cycloalk-2-en-1-ones, ketalization, Tamao-Fleming oxidation (Bu4NF, then H2O2, KHCO3), TPAP oxidation and acid hydrolysis generates 2-methyl cycloalkane-1,3-diones. Ketalization is needed in order to prevent addition of Me3Si- to the carbonyl. The pentamethyldisilanyl group has advantages over other silicon units that are used in Tamao-Fleming procedures.