2-Cyclopentene-1-one

Although 1-vinylnaphthalene thermally reacts with 4-acetoxy-2-cyclopenten-1-one (98) to regioselectively afford 99, the isomer 2-vinylnaphthalene gives the same thermal cycloaddition with low yield (30 %) and reacts satisfactorily only with 98 at 10 kbar (Scheme 5.10). Both products 99 and 101 were converted into the cyclopenta[a]phenanthren-15-one (100) and cyclopenta[c]phenanthren-l-one (102) isomers. Acetoxyketone 98 acts as a synthetic equivalent of cyclo-pentadienone (114 in Scheme 5.14) in cycloaddition reactions [33]. 

It is assumed that the reaction proceeds by the oxidative addition of the carbon-carbon bond of the cyclopropane to cobalt species to form a metallacyclic intermediate. The regioselectivity of this reaction is controlled by the relative ease of insertion of the cobalt species into the C1-C2 and the C1-C3 bonds of the cyclopropane (Scheme 7). In the case of the reaction of the (1-R, 2k )-isomer trans-l5a, 5-methyl-3-phenyl-2-cyclopenten-1-one (17a) is produced via TS2 without any serious steric repulsion, while the 4-methyl isomer 16a must be pro-... 

USEPA (2009) Maple lactone (2-cyclopenten-1-one, 2-hydroxy-3-methyl) (004049) Fact Sheet http //www.epa.gov/ oppbppdl /biopesticides / ingredients / factsheets/factsheet 0040 49.htm (last accessed 30 April 2010). 

Many cyclic ketones occur in natural oils. Jasmone [488-10-8] (3-methyl-2-(2-pentyl)-2-cyclopenten- 1-one) (4) is an odoriferous component of the oil obtained from jasmine flowers. /-Menthone [14073-97-3] (5) is the most frequently occurring of four optically active isomers, and is a colorless liquid with a minty odor obtained from Mentha species of plants. Muscone [541 -91-3] (6) and civetone [542 -6-1] (7) are expensive animal products. 

CYCLOPENTANONE SYNTHESIS, 66, 87, 92, 93 Cyclopentanone, 2-carbomethoxy-3-vinyl, 66, 56 Cyclopentanone, 2-ethenyl-2-methyl (88729-76-4), 66, 94 Cyclopentene (142-29-0), 67, 157 4-Cyclopentene-1,3-diol, monoacetate, cis-, 67, 114 2-Cyclopenten-1-one, 4,4-dimethyl-, 67, 121,205 2-CYCLOPENTEN-1 -ONE, 3-METHYL-2-PENTYL-, 65, 26 CYCLOPROPANATION, 67, 176... 

O-Hydroxyethylresorcinol, hi 59 2-Hydroxyisobutyronitrile, hi 45 2-Hydroxy-3-methyl-2-cyclopenten-1 -one, m214... 

HETHYL-2-PENTYL-2-CYCL0PENTEN-1-0HE (DIHYDROJASMONE) (2-Cyclopenten-1-one, 3-methyl-2-pentyl-)... 

Charge the flame dried and argon flushed three-necked flask with THF (2 mL), NMP (3 mL), and 2-cyclopenten-1-one. 

Prepare a solution of 3-methyl-2-cyclopenten-1-one (0.384 g, 4 mmol) and Ni(acac)2 (21 mg, 0.08 mmol) in 5 1, toluene tetrahydrofuran (2 mL), and slowly add this solution to the organozinc reagent prepared above at 0°C. 

SULFONYL)M ETHYL] FUR AN AND 2-METHYL-3-[(PHENYLSULFONYL)METHYL]-2-CYCLOPENTEN-1-ONE (Benzene, [(2,3-dlbromO 1-propenyl)sulfonyl]>, Furan, 2-methyl-4-[(phenylsulfonyl)methyl]-, and 2-Cyclopenten-l-one,... 

D. 2-Methyl-3-[(phenylsulfonyl)methyll-2-cyclopenten-1 -one. In aflame-dried, 1-L, round-bottomed flask equipped with an addition funnel under a nitrogen atmosphere are placed 20.0 g (58.8 mmol) of 2,3-dibromo-1-(phenylsulfonyl)-1-propene and 7.0 mL (60.0 mmol) of 3-methyl-2,4-pentanedione in 300 mL of methanol (Note 8). The flask is cooled using an ice-water bath. To this mixture is added 140 mL... 

Methyl-3-[(phenylsulfonyl)methyl]-2-cyclopenten-1 -one (12) 2-Cyclopenten-1-one, 2-methyl-3-[(phenylsulfonyl)methyl]- (12) (132604-66-1)... 

METHYL-4-[(PHENYLSULFONYL)-METHYL]FURAN AND 2-METHYL-3-[(PHENYLSULFONYL)METHYL]-2-CYCLOPENTEN-1-ONE... 

R)-(+)-tert-BUTYLDIMETHYLSILOXY-2-CYCLOPENTEN-1-ONE (2-Cyclopenten-l-one, 4-[[(l,l-dlmethylethyl)dlmethylsllyl]oxy]-, (R)-)... 

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