1121-05-7

Basic information

• Product Name: 2,3-DIMETHYL-2-CYCLOPENTEN-1-ONE
• Synonyms: 2,3-dimethylcyclopent-2-en-1-one;2-Cyclopenten-1-one, 2,3-dimethyl-;Cyclopent-2-en-1-one, 2,3-dimethyl;2,3-DIMETHYL-2-CYCLOPENTEN-1-ONE;2,3-Dimethylcyclopenta-2-en-1-one;2,3-DiMethyl-2-cyclopenten-1-one 99%
• CAS NO: 1121-05-7
• Molecular Formula: C₇H₁₀O
• Molecular Weight: 110.15
• Product Categories: C7 to C8;Carbonyl Compounds;Ketones
• Mol File: 1121-05-7.mol
• Article Data: 44

Chemical Properties

• Boiling Point: 80 °C10 mm Hg(lit.)
• Flash Point: 162 °F
• Appearance: /
• Density: 0.968 g/mL at 25 °C(lit.)
• Vapor Pressure: 1.33mmHg at 25°C
• Refractive Index: n20/D 1.49(lit.)
• CAS DataBase Reference: 2,3-DIMETHYL-2-CYCLOPENTEN-1-ONE(CAS DataBase Reference)
• NIST Chemistry Reference: 2,3-DIMETHYL-2-CYCLOPENTEN-1-ONE(1121-05-7)
• EPA Substance Registry System: 2,3-DIMETHYL-2-CYCLOPENTEN-1-ONE(1121-05-7)

Safety Data

• RIDADR: NA 1993 / PGIII
• WGK Germany: 3
• Hazardous Substances Data: 1121-05-7(Hazardous Substances Data)

Usage

Synthesis Reference(s)

The Journal of Organic Chemistry, 45, p. 2736, 1980 DOI: 10.1021/jo01301a046Tetrahedron Letters, 12, p. 2575, 1971 DOI: 10.1016/S0040-4039(01)96923-0Synthetic Communications, 21, p. 17, 1991 DOI: 10.1080/00397919108020785

InChI:InChI=1/C7H10O/c1-5-3-4-7(8)6(5)2/h3-4H2,1-2H3

Upstream product

• 510-18-9 5-acetoxy-3-acetyl-3,4-dimethyl-dihydro-furan-2-one 
• 623-11-0 1-methyl-4-nitrosobenzene 
• 57374-43-3 1-Acetoxy-2.3-dimethylcyclopenten 
• 918-86-5 3-Methyl-1,4-pentadien-3-ol 
• 201230-82-2 carbon monoxide 
• 80864-39-7 2,3-Dimethyl-2-phenylselanyl-cyclopentanone 
• 917-64-6 methyl magnesium iodide 
• 4933-43-1 5-methyl-2-(1-pyrrolidinyl)-2-cyclopenten-1-one 
• 109-72-8 n-butyllithium 
• 503-17-3 dimethylacetylene 
• 769-78-8 vinyl benzoate 
• 74-85-1 ethene 
• 127229-65-6 ethyl 2-chloro-3-methylbut-3-enoate 
• 127229-64-5 Ethyl 2-chloro-2,3-dimethyl-3-butenoate 

Downstream Products

• 38693-65-1 2,3-Dimethyl-cyclopent-2-enethione 
• 488-23-3 1,2,3,4-Tetramethylbenzene 
• 527-53-7 1,2,3,5-Tetramethylbenzene 
• 3031-15-0 1,2,3,4-tetramethylnaphthalene 
• 483-78-3 cadalene 
• 94133-80-9 1,7- diisopropylnaphthalene 
• 2717-39-7 1,4,5,8-tetramethylnaphthalene 
• 1123-09-7 3,5-dimethyl-2-cyclohexen-1-one 
• 54562-24-2 2,3-dimethyl-5-methyl-2-cyclopentenone 
• 72784-83-9 4-Methyl-3-hept-5-en-2-yl>pentene 
• 56775-43-0 3-hept-5-en-2-yl>propyne 
• 56775-40-7 2-Formyl-5,6-dimethylbicyclo<2.2.1>hepta-2,5-diene 
• 78303-49-8 2,3-dimethyl-5-phenyl-2-cyclopentenone 

Relevant articles and documents

A New Synthesis of Cyclopentenones: Dihydrojasmone

A new general olefin synthesis, via alkylation of an alpha-trifyl sulfone and subsequent Ramberg-Baecklund elimination of triflinate and SO2, is here applied to the synthesis of cyclopentenones, including dihydrojasmone and methylenomycin B.

Pheromone synthesis. Part 262: Determination of the absolute configuration of the female sex pheromone [(1S,2S)-(?)-(1,2-dimethyl-3-methylenecyclopentyl) acetaldehyde] of the pineapple mealybug (Dysmicoccus brevipes) by synthesis coupled with X-ray analysis

The enantiomers of (anti-1,2-dimethyl-3-methylenecyclopentyl)acetaldehyde, one of which is the female sex pheromone of the pineapple mealybug (Dysmicoccus brevipes), were synthesized. Chirality was introduced by means of lipase-catalyzed asymmetric acetylation of (±)-2,3-dimethyl-2-cyclopenten-l-ol. X-ray analysis of (?)-camphanate ester of (1S,2S)-(?)-2-(1,2-dimethyl-3-methylenecyclopentyl)ethanol confirmed its (1S,2S)-absolute configuration. The natural pheromone was identified with the (1S,2S)-aldehyde by comparing the specific rotation, enantioselective GC retention time and pheromone activity.

Synthesis of substituted 2-cyclopenten-1-ones from oxodithioesters via a domino process

Freshly prepared sulfines of δ-oxodithioesters underwent chemoselective addition of methyllithium to the electron poor sulfur atom of the thiocarbonyl moiety. Subsequent ring closure was effected by intramolecular addition of the carbanion, generated in situ, to the 8-carbonyl function leading to 2-cyclopenten-1-ones. While most described intramolecular procedures involve a base-catalysed cyclisation, our method is induced by an addition reaction. It is a new efficient synthesis of substituted 2- cyclopenten-1-ones via a domino process.

Pheromone synthesis. Part 260: Synthesis of (±)-(anti-1,2-dimethyl-3-methylenecyclopentyl)acetaldehyde, the racemate of the female-produced sex pheromone of the pineapple mealybug (Dysmicoccus brevipes), and its syn-isomer

(±)-(anti-1,2-Dimethyl-3-methylenecyclopentyl)acetaldehyde, the racemate of the female-produced sex pheromone of the pineapple mealybug, was synthesized in four different ways. Ireland–Claisen rearrangement or conjugate addition was employed for the const

SYNTHESIS OF CYCLOPENTANOID NATURAL PRODUCTS VIA VINYL PHOSPHONIUM SALTS

Cyclopentenones obtained from cyclisations involving phosphonium salts are converted to dihydrojasmone, dihydrojasmolone and known precursors of methylenomycins A and B.

SYNTHESIS OF MONO- AND 1,4-DICARBONYL COMPOUNDS BASED ON THE OXYGENATION OF PHOSPHONATE CARBANIONS. SYNTHESIS OF DIHYDROJASMONE, ALLETHRONE AND METHYLENOMYCIN B

Oxidation of the α-alkylthio-substituted phosphonate carbanions was found to give the corresponding carbonyl compounds.A new synthesis of 1,4-dicarbonyl systems involving the oxygenation of phosphonate carbanions as a key step is described.Total synthesis of dihydrojasmone and allethrone and formal synthesis of methylenomycin B is reported.

Cyclopentenones from the Acid-induced Ring Expansion of 1-Alkenylcyclopropanol Derivatives

1-Alkenylcyclopropanols (4a,b) and (5a,b) underwent acid-induced ring expansion into cyclopentenones (7), via 2-alkenylcyclobutanones (6); the 2-methylcyclopropanols (15a,b) are also synthesised using the same method.

Polymer-mediated reactions. A Nazarov-like cyclization

The polymer PEDOT+ mediates a Nazarov-like cyclization of dienones, in an heterogeneous system and in hydrocarbon solvents. The polymer-mediated reactions show clear differences in product formation when compared to the same reaction with tosic acid, or when compared to reports in the literature. Comparable or improved yields are observed, as well as the ability to give a -Nazarov product in cases where treatment with acid fails to give cyclization, or leads to an undesirable rearrangement. In addition, the ability to recycle the polymer makes this a potentially useful protocol for an important organic chemical reaction. Georg Thieme Verlag Stuttgart · New York.

A new synthetic route to methylenomycin B via Rhodium(II)-mediated decomposition of α,β-unsaturated α'-diazoketones

A new synthesis of methylenomycin B, involving Rh(II)-catalyzed, intramolecular carbon-hydrogen insertion of diazoketone 2c, derived from 2,3-dimethyl-2-butenoic acid 2b, is reported.

Acyclic O- and N-substituted Pentadienyl Cations: Structural Characterisation, Cyclisation and Computational Results

A number of 1- and 3-hydroxy and 1-amino substituted acyclic pentadienyl cations have been characterised by NMR spectroscopy in situ at low temperature.Some of the 3-hydroxy cations undergo cyclisation to give 1-hydroxycyclopentenyl cations which on deprotonation give substituted cyclopentenones.