2-Cyclopentene-1 -acetic acid

Campos et al. reported asymmetric synthesis of the DP receptor antagonist 42 starting from (f )-2-cyclopentene-1-acetic acid obtained via asymmetric allylic... 

Cll,Hl,)N07 78858-51-2) see Amoxicillin [15-(la,4[Pg.2399]

C7H10CI2N2OPt dich oro(4-methoxy-0-phenylenediammine)plati 72595-97-2 480.15 41,980 1,2 11174 C7H10O2 2-cyclopentene-1-acetic acid 13668-61-6 366.15 31.188 1,2... 

A. 2-Cyclopentene-1-acetamide. A dry, 250-mL, three-necked, round-bottomed flask is equipped with a magnetic stirring bar, serum stopper, 25-mL pressure equalizing addition funnel, and an argon atmosphere with provision for venting gaseous reaction products (Note 1). The vessel is charged with 20 g (152 mmol) of 2-cyclopentene-1-acetic acid (Note 2) and 25 mL of dry toluene (Note 3). Oxalyl chloride (17.3 mLi 1.3 equiv) is added slowly over a 30-min period by means of the addition... 

Cyclopentene-1-acetic acid (96%) was purchased from Aldrich Chemical Company, Inc., and used as received. 

The presence of the catalyst can also favor multiple Diels-Alder reactions of cycloalkenones. Two typical examples are reported in Schemes 3.6 and 3.7. When (E)-l-methoxy-1,3-butadiene (14) interacted with 2-cyclohexenone in the presence of Yb(fod)3 catalyst, a multiple Diels-Alder reaction occurred [21] and afforded a 1 1.5 mixture of the two tricyclic ketones 15 and 16 (Scheme 3.6). The sequence of events leading to the products includes the elimination of methanol from the primary cycloadduct to afford a bicyclic dienone that underwent a second cycloaddition. Similarly, 4-acetoxy-2-cyclopenten-l-one (17) (Scheme 3.7) has been shown to behave as a conjunctive reagent for a one-pot multiple Diels-Alder reaction with a variety of dienes under AICI3 catalysis, providing a mild and convenient methodology to synthesize hydrofluorenones [22]. The role of the Lewis acid is crucial to facilitate the elimination of acetic acid from the cycloadducts. The results of the reaction of 17 with diene... 

The product, l,4-diacetoxy-2-allyl-3-methyl-2-cyclopentene, obtained (45% current efficiency) from 2-allyl-3-methyl-l,3-cyclopentadiene through anodic oxidation with carbon rod anode in acetic acid is successfully used as a starting compound in the synthesis of allethrolone as shown in equation 23. 

In fluorosulfonic acid the anodic oxidation of cyclohexane in the presence of different acids (RCO2H) leads to a single product with a rearranged carbon skeleton, a 1-acyl-2-methyl-1-cyclopentene (1) in 50 to 60% yield (Eq. 2) [7, 8]. Also other alkanes have been converted at a smooth platinum anode into the corresponding a,-unsaturated ketones in 42 to 71% yield (Table 1) [8, 9]. Product formation is proposed to occur by oxidation of the hydrocarbon to a carbocation (Eq. 1 and Scheme 1) that rearranges and gets deprotonated to an alkene, which subsequently reacts with an acylium cation from the carboxylic acid to afford the a-unsaturated ketone (1) (Eq. 2) [8-10]. In the absence of acetic acid, for example, in fluorosulfonic acid/sodium... 

The proposed mechanism involves the formation of ruthenium vinylidene 97 from an active ruthenium complex and alkyne, which upon nucleophilic attack of acetic acid at the ruthenium vinylidene carbon affords the vinylruthenium species 98. A subsequent intramolecular aldol condensation gives acylruthenium hydride 99, which is expected to give the observed cyclopentene products through a sequential decarbonylation and reductive elimination reactions. 

Of the four possible optical isomers, the (+)-( I )-cw-isomer possesses the most characteristic jasmin odor. Methyl dihydrojasmonate is prepared by Michael addition of malonic acid esters to 2-pentyl-2-cyclopenten-l-one, followed by hydrolysis and decarboxylation of the resulting (2-pentyl-3-oxocyclopentyl) malonate, and esterification of the (2-pentyl-3-oxocyclopentyl)acetic acid [136]. 

The cold filtrates (solutions of monochlorourea) are transferred to a 3-1. two-necked flask immersed in an ice-salt bath. The flask is equipped with a slip- or mercury-sealed mechanical stirrer and an efficient reflux condenser. To the flask are added 500 g. of ice, 100 ml. of glacial acetic acid, and 136 g. (2.0 moles) of cyclopentene (or 1.43 times the weight increase in grams during introduction of the chlorine) (Note 4). Mechanical stirring is begun, and is continued while the flask is kept packed in ice until the cyclopentene (the top layer) disappears and a heavy oil settles to the bottom (Note 5). 

This subject has recently been reviewed.647 Several additional papers have appeared on the catalytic oxidation of alkenes by 02 in the presence of PdCl(MeCN)2N02(148).64S Terminal alkenes and trans- cyclooctene yield the corresponding ketones, cyclopentene and cyclohexene the corresponding allyl alcohol, and bicyclic alkenes the corresponding epoxide. Heterometallacy-clopentanes such as (152) have been isolated from the reaction of (148) with norbornene (dicy-clopentadiene), and characterized by X-ray crystallography.6486 Glycol monoacetates were obtained from the reaction of (148) with terminal alkenes in acetic acid.649... 

Exclusive enone formation could be achieved by electrocatalytic oxygenation of 2-cyclopentene-l-acetic acid in the presence of a water-soluble iron(III) porphyrin (2-TMPyP)Fe [2-TMPyP =tetrakis(N-methyl-2-pyridyl)porphyrin]. Unfortunately, neither yields nor TONs are given [116]. 

Methyl (1R,5R) -5-hydroxy-2-cyclopentene-l-acetate 2-Cyclopentene-l-acetic acid, 5-hydroxy-, methyl ester, (lR-trans)- (9) (49825-99-2) Dicyclopentadiene 4,7-Methanoindene, 3a,4,7,7a-tetrahydro- (8) 4,7-Methano-lH-1ndene, 3a,4,7,7a-tetrahydro- (9) (77-73-6)... 

During the photocycloaddition of 88 with cyclopentene (Reaction 1), de of the major isomer 89 increased from 30% in nonpolar solvents up to 68 in a mixture of methanol and acetic acid. When prochiral enone 91 was irradia in the presence of a cyclopentene linked to the 8-phenylmenthol (Reaction the best selectivity was now obtained in nonpolar solvents. To explain this eff< it was proposed that the facial selectivity is high in every case and that diastereoselectivity depends on an s-cis s-trans ratio of the conjugated es influenced by hydrogen bonding [65]. Similar results were obtained with c... 

Baeyer- Villiger oxidation of 2,2,3-trimethyl-5-oxo-3-cyclopentene-l-acetic acid (20) by the resting cells of a Pseudomonas species, with addition of 2,2 -bipyridine. permits the accumulation of dihydropyran 21 without further degradation402. 

Cyclopentene-l,4-dione has been prepared by oxidation of 2-cyclopentene-l,4-diol with chromium trioxide in aqueous acetic acid or in aqueous acetone, and with silver chromate. The present method eliminates the tedious removal of large amounts of acetic acid and gives a higher yield. 

Cyclopentene-oxo-ozonides. A monomer, CsHgOa, was prepd (Ref 2) by the ozonization of cyclo-pentene dissolved in CCI4. It is a yel, volatile liq with a penetrating odor sol in chlf, ethyl acetate and acetic acid is decompd explosively by coned sulfuric acid explds on heating... 

C7H10 2-methyl-1 -hexen-3-yne 23056-94-2 389.65 33.391 1,2 11167 C7H10O2 3-cyclopentene-1-acetic acid 767-03-3 446.44 C Iii... 

For strained bicyclic molecules such as bicyclo[2.1.0]pentane calculations suggest a strong preference for protonation at a bridgehead carbonThis prediction seems to be consistent with experimental results in which bicyclo[2.1.0]pentane-endo-5-d is solvolyzed in acetic acid containing p-toluenesulfonic acid to give cyclopentyl acetates and tosylates (as well as some cyclopentene) in which distribution of the deuterium among all possible sites could be quantified. Isotope effects and label distributions were found to be consistent with the initial formation of a C(l)-protonated bicyclo[2.1.0]pentane. 

Figure 5.2.10. Cellulose pyrolysate obtained at 59CP C by Py-GC/MS. The separation was done on a Carbowax type column. 1 CO2, 2 acetaldehyde, 3 acetone, 4 2-butanone, 5 2,3-butandione, 6 toluene, 7 water, 8 cyclopentanone, 9 methylfuran, 10 3-hydroxy-2-butanone, 11 hydroxypropanone, 12 cyclopent-1-en-2-one, 13 2-methylcyclopentenone, 14 acetic acid, 15 acetic acid anhydride, 16 furancarboxaldehyde, 17 methylcyclopentenone, 18 dimethylcyclopentenone, 19 5-methylfurancarboxaldehyde, 20 2,3-dihydro-2-furanone, 21 furan-2-methanol, 22 3-methylfuran-2-one, 23 2(5H)-furanone, 24 hydroxycyclopentenone, 25 3,5-dimethylcyclopentan-1,2-dione, 26 2-hydroxy-3-methyl-2-cyclopenten-1-one, 27 2-hydroxy-3-ethyl-2-cyclopenten-1-one, 28 2,3-dimethyl-2-cyclopenten-1-one, 29 phenol, 30 dimethylphenol, 31 3 thyl-2,4(3H,5H)-furandione, 32 3-butenoic acid, 33 1,4 3,6-dianhydro-a-D-glucopyranose, 34 5-(hydroxymethyl)-furfural.

Figure 7.1.1. Chromatogram for the pyrotysate ofgtucose obtained by on-line Py-GC/MS. The peak assignments are 1 furan, 2 2-melhylfuran, 3 2,5-dimethylfuran, 4 3-methyl-2-butanone, 5 water, 6 1-hydroxypropanone, 7 hydroxyacetaldehyde, 8 acetic acid, 9 oxopropanoic acid methyl ester, 10 furancarboxaldehyde, 11 1-(2-furanyl)-ethanone, 12 5-methyl-2-furfural, 13 2-hydroxycyclopent-2-en-1-one, 14 2-hydroxy-3-methyl-2-cyclopenten-1-one, 15 2,3-dihydro-5-hydroxy-6-methyl-4H-pyran-4-one, 16 2-methyl-1,3-benzendiol, 17 2,5-dimethyldioxane, 18 2-hydroxy-3-pentanone, 19 5-formyl-2-fufurylmethanoate, 20 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 21 1,4 3,6-dianhydro-a-D-glucopyranose, 22 5-(hydroxymethyl)-furancarboxaldehyde.

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