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Pentenoic acid esters

Ester enolates react with 3,3,3-trifluoropropene by an Sf,2 -ty pe process to gi ve 5 5 difluoro-4-pentenoic acid esters [130] (equation 112)... [Pg.476]

In the second step, the concentration of pyridine as ligand must be low because it has an inhibitory effect on the hydroalkoxycarbonylation. In situ isomerization to the 4-pentenoic acid ester is a prerequisite for the subsequent carbonylation which provides dimethyl adipate. To ensure internal double-bond rearrangement, the temperature of the reaction is increased to 160-200 °C to give dimethyl adipate with 80 % selectivity. After hydrolysis of the ester, adipic acid is obtained with an overall selectivity of about 70% [1]. So far, this process has been performed on pilot-plant scale. [Pg.188]

This reaction has been modified to react with 4-pentenoic acid ester to form alkyl-substituted phenanthrenes directly. In addition, the first step of acylation has alternatively been carried out by the reaction of succinic anhydride with an aryl Grignard reagent. ... [Pg.1343]

Fujino, A. and Sugai, T. (2008) Chemoenzymatic approach to enantiomerically pine (R)-3-hydroxy-3-methyl-4-pentenoic acid ester and its application to a formal total synthesis of taurospongin A. Adv. Synth. Catal., 350,1712-1716. [Pg.228]

This useful annelation procedure for fusion of 2-carboxy-A -cyclohexenone systems to a preexisting ring was previously marred by the difficult accessibility of 3-oxo-4-pentenoic acid ester. An efficient synthesis of this compound has now been devised by G. Stork and R. N. Guthikonda, Tetrahedron Lett, 2755 (1972). [Pg.316]

Obviously, the use of a nonvolatile ionic liquid simplifies the distillative workup of volatile products, especially in comparison with the use of low-boiling solvents, where it may save the distillation of the solvent during product isolation. Moreover, common problems related to the formation of azeotropic mixtures of the volatile solvents and the product/by-products formed are avoided by use of a nonvolatile ionic liquid. In the Rh-catalyzed hydroformylation of 3-pentenoic acid methyl ester it was even found that the addition of ionic liquid was able to stabilize the homogeneous catalyst during the thermal stress of product distillation (Figure 5.2-1) [21]. This option may be especially attractive technically, due to the fact that the stabilizing effects could already be observed even with quite small amounts of added ionic liquid. [Pg.217]

Another application of this method is the stereoselective addition of (7 )-2-hydroxy-l,2,2-triphenylethyl acetate, via the lithium enolate, to propenal (acrolein) which affords mainly the ester 13 (d.r. 92 8). When the acid, obtained in the subsequent alkaline hydrolysis, is converted into the ammonium salt derived from (.S)-l -phenylethylaminc, and the salt recrystallized once, then the amine liberated (/f)-3-hydroxy-4-pentenoic acid is obtained in 41 % yield [relative to the (/ )-acetate] and >99.8% ee82. [Pg.492]

C5H4N2O 1003-52-7) see Pyridoxine 2-cyano-3-methyl-2-pentenoic acid ethyl ester (C HijNOj 759-51-3) see Ethosuxiinide... [Pg.2339]

ETHYL 3-OXO-4-PENTENOATE (NAZAROVS REAGENT) (4-Pentenoic acid, 3-oxo-, ethyl ester)... [Pg.119]

A more useful way of reducing esters to ethers is a two-step procedure applied to the reduction of lactones to cyclic ethers. First the lactone is treated with diisobutylaluminum hydride in toluene at —78°, and the product - a lactol - is subjected to the action of triethylsilane and boron trifluoride etherate at —20° to —70°. y-Phenyl-y-butyrolactone was thus transformed to 2-phenyltetrahydrofuran in 75% yield, and 5-lactone of 3-methyl-5-phenyl-5-hydroxy-2-pentenoic acid to 4-methyl-2-phenyl-2,3-dihydropyran in 72% yield [1034]. [Pg.150]

DSM jointly with Du Pont de Nemours308 have patented platinum catalysts generated from the water soluble sulfonated ligand 30 (Table 2 m=0, n=0, m=l, n=2 m=l, n=l, Ar=nBu-S03Li) and used in the aqueous phase hydroformylation of internally unsaturated carboxylic acids, esters or nitriles to their corresponding formyl derivatives which are useful intermediates for the preparation of di-carboxylic acids (e.g. adipic acid). For example, TOFs up to 105 h-1 were achieved in the hydroformylation of 3-pentenoic acid catalysed by Pt/30 (m=0, n=0) at 100°C and 80 bar CO/H2 to give aldehydes with a selectivity of 83% (n/i=3.4), valeric acid (4.6%) and adipic acid (8.1%).308 The products were separated from the aqueous catalyst solution by extraction with ether. Five recycles of the aqueous catalyst solution showed that the Pt/30 (m=0, n=0) catalyst retains its activity. [Pg.152]

Desaturation of alkyl groups. This novel reaction, which converts a saturated alkyl compound into a substituted alkene and is catalyzed by cytochromes P-450, has been described for the antiepileptic drug, valproic acid (VPA) (2-n-propyl-4-pentanoic acid) (Fig. 4.29). The mechanism proposed involves formation of a carbon-centered free radical, which may form either a hydroxy la ted product (alcohol) or dehydrogenate to the unsaturated compound. The cytochrome P-450-mediated metabolism yields 4-ene-VPA (2-n-propyl-4pentenoic acid), which is oxidized by the mitochondrial p-oxidation enzymes to 2,4-diene-VPA (2-n-propyl-2, 4-pentadienoic acid). This metabolite or its Co A ester irreversibly inhibits enzymes of the p-oxidation system, destroys cytochrome P-450, and may be involved in the hepatotoxicity of the drug. Further metabolism may occur to give 3-keto-4-ene-VPA (2-n-propyl-3-oxo-4-pentenoic acid), which inhibits the enzyme 3-ketoacyl-CoA thiolase, the terminal enzyme of the fatty acid oxidation system. [Pg.92]

Both [Pd(OAc)2] and [Pd(acac)2] were used as catalyst precursors, in the presence of PPh3 or PBun3. No catalysis occurred here in absence of the phosphorus ligand. When isoprene was carbonylated using [Pd(OAc)2] and PPh3 as catalyst precursor, dimerization of the alkene did not take place, the ester of 4-methyl-3-pentenoic acid being formed as the only product.529... [Pg.288]

BENZYL-L-GLYCER ALDEHYDE AND ETHYL (R,E)-4-0-BENZYL-4.5-DIHYDROXY-2-PENTENOATE (Propanal, 3-hydroxy-2-(phenylmethoxy)-, (R)- and 2-Pentenoic acid, 5-hydroxy-4-(phenylmethoxy)-, ethyl ester, [R-(E)]-)... [Pg.1]

The stereoselectivity of the amide reaction appears relatively low in comparison with the corresponding esters. In fact, under the same conditions, methyl 3-methyl-4-pentenoate gives 93 7 (transjeis) ratio of -/-lactones in 73% yield, while 3-methyl-4-pentenoic acid gives 91 9 (trans/ a s) ratio in 83% overall yield22. [Pg.221]

Mild conditions should be employed in alkaline hydrolysis of olefinic esters. Double bonds in many acids migrate readily during saponification. Aqueous alcoholic sodium hydroxide is used in the preparations of 3-ethyl-3-pentenoic acid (56%) and /S-methylcinnamic acid (41%). ... [Pg.660]

Other Enantioselective Transformations Mediated by Ti-TADDOLates. The iodolactonization of 2-allyl-2-hydroxy-4-pentenoic acid shown in eq 8 gives (21) in a 67% yield (after cyclization of some iodo isopropyl ester formed as a side product), the iodolactone is a single (—)-diastereoisomer with a 5 1 (S,S)I(R,R) ratio. The TADDOLate generated in situ was employed in stoichiometric amount. The two enantiomers of 2-pyridyl 2-phenylthiobutyrate react with a rate difference of 39 1 with excess isopropanol in the presence of 0.1 equiv of a Ti-TADDOLate under the conditions specified in eq 9. This leads to the isopropyl ester (22) containing 96% of the (/ )-enantiomer... [Pg.291]


See other pages where Pentenoic acid esters is mentioned: [Pg.78]    [Pg.78]    [Pg.550]    [Pg.87]    [Pg.1342]    [Pg.121]    [Pg.826]    [Pg.78]    [Pg.78]    [Pg.550]    [Pg.87]    [Pg.1342]    [Pg.121]    [Pg.826]    [Pg.36]    [Pg.217]    [Pg.87]    [Pg.2339]    [Pg.917]    [Pg.12]    [Pg.904]    [Pg.631]    [Pg.631]    [Pg.462]    [Pg.491]    [Pg.867]    [Pg.288]    [Pg.204]   
See also in sourсe #XX -- [ Pg.78 ]




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3- Pentenoic acid

3-pentenoic acid methyl ester

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