3-pentenoic acid methyl ester

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. 

Dimethyl-4-pentenoic acid, methyl ester EINECS 264-431-8 Methyl 3,3-dimethyl-4-pentenoate Methyl 3,3-dimethylpent-4-enoate 4-Pentenoic acid, 3,3-dimethyl-, methyl ester Penten-4-oic acid, 3,3-dimethyl, methyl ester,... 

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

The hydroformylation of co-alkene carboxylic acid methyl esters catalysed by a Rh/TPPTS system (Scheme 1.22) in a biphasic medium does not require additives with low molecular substrates such as methyl 4-pentenoate, whereas methyl esters of higher co-alkene carboxylic acids such as methyl 13-tetra-decenoate require the presence of surfactants as mass-transfer promoters. Surfactants, indeed, decrease the interfacial tension, forming aggregates above the critical micellar concentration that speed up the catalytic process by increasing the interfacial area. 

From a regio- and chemoselectivity point of view, the behavior of this class of alkenes is very similar to that observed with unfunctionalized alkenes in biphasic medium. As expected for a biphasic medium, the catalytic activities are comparable with or lower than those observed under similar homogeneous conditions, and strongly dependent on the water-solubility of the alkene. Addition of solubilizing agents is often necessary for high-molecular-mass alkenes. For instance, low-mo-lecular-mass co-alkenecarboxylic acid methyl esters such as methyl 4-pentenoate can be hydroformylated efficiently in biphasic systems whereas methyl esters of higher w-alkenecarboxylic acids such as methyl 13-tetradecenoate require the presence of surfactants (Eq. 1) [9]. 

Barrett and co-workers prepared a key intermediate oxazole 350 in their synthesis of calyculin A using Comforth methodology (Scheme 1.94). The benzyl ester of (/ )-2-methyl-4-pentenoic acid 347 was converted to (/ )-2-methyl-4-pentenenitrile 348 in two steps. Pinner reaction of 348, followed by amine exchange with glycine methyl ester, gave the imidate 349 in 73% yield. Base-catalyzed formylation of 349 with in situ cyclization produced the 2-alkyl-4-oxazolecarboxylic acid methyl ester 350 in good yield. This entire sequence... 

Hydroformylation of -alkene carboxylic acid methyl esters catalyzed by a Rh/ TPPTS system was initially investigated by Fell et al. (Eq. (1)]. As expected in a biphasic medium, low molecular (o-alkene carboxylic acid methyl esters such as methyl 4-pentenoate can be hydroformylated efficiently without any additives whereas methyl esters of higher (<>-alkene carboxylic adds such as methyl 13-tetra-decenoate require the presence of mass-transfer promoters such as surfactants [3] or chemically modified y9-cyclodextrins [4]. 

ASYMMETRIC CATALYTIC GLYOXYLATE-ENE REACTION METHYL (2R)>2 HYDROXY-4-PHENYL-4 PENTENOATE (Benzenabutanoic acid, a-hydroxy-y-methylene, methyl ester, (R)-)... 

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]. 

ETHYL (1-ETHYLPROPEN YL)-METHYLCYAN OACETATE (3-Pentenoic acid, 2-cyano-3-ethyl-2-methyl-, ethyl ester)... 

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... 

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. 

Both [Pd(OAc)2] and [Pd(acac)2] were used as catalyst precursors, in the presence of PPhs or PBu"3. No catalysis occurred here in absence of the phosphorus ligand. When isoprene was carbonylated using [Pd(OAc)2] and PPhj 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. Because of its potential application to the synthesis of esters for lubricating oils, the dimerization-carbonylation of butadiene has received special attention. Basic phosphines such as PBu°3 and weakly basic tertiary amine solvents (quinoline, N,N-diethylaniline) were found to improve both the stability and activity of the catalyst system.In a further report in which PPr 3 was used as phosphorus ligand it was found that the addition of maleic anhydride caused a marked increase in the catalytic activity. It was believed that through coordination it stabilized the palladium(O) complexes formed against precipitation as metal. ... 

Burke discloses a two-step process for the conversion of butadiene to adipic acid at high yields [156]. The first step is the hydrocarboxylation of butadiene to form 3-pentenoic acid. The second step is the hydrocarboxylation of 3-pentenoic acid with carbon monoxide and water in the presence of a rhodium-containing catalyst, an iodide promoter, and certain inert solvents such as methylene chloride. The first reaction step gives also a significant by-product of y-valerolactone and a minor by-product of a-methyl-7-butyrolactone. These lactones can be converted to adipic acid by modified catalyst compositions [157-159]. In a related work, pentenic acids or esters are used as the starting intermediates for conversion to adipic acid [160-166]. 

Butadiene, which is bound in a n -manner to iron, reacts stoichio-metrically with carbon dioxide to form an allyl carboxylato complex in yields up to 75 % [38]. This allyl complex shows a dynamic behaviour Presumably three isomeric structures exist in solution, two of them with a n"-allyl bonding (Figure 16). Subsequent reactions of the allyl carboxylato complexes yield carboxylic acids. Acidic hydrolysis in methanol at -30°C gives methyl-3-pentenoate and methyl-4-pentenoate in a ratio of 10 1. If the iron allyl complex reacts with further carbon dioxide at 90 C, a second insertion of CO2 into the Fe-C-bond occurs after hydrolysis with hydrochloric acid in methanol the Z- and E-dimethyl esters of 3-hexenedioic acid are formed. 

Sato, T., K. Tajima, and T. Fujisawa Diastereoselective synthesis of erythro- and threo-2-hydroxy-3-methyl-4-pentenoic acids by the ester enolate Claisen rearrangement of 2-butenyl 2-hydroxy acetate. Tetrahedron Letters 24, 729 (1983). 

Figure 17 During 5 min subjects were exposed to the E-isomer of the ethyl ester of 3-methyl-2-pentenoic acid (E-EE3M2PA), which has a floral odor. Every 15 sec they were asked to rate the intensity of either E-EE3M2PA or mercaptoethanol (a sulfurous malodor) across 11 min (except for the 1 min between adaptation to E-EE3M2PA and recovery from adaptation). Relative to estimates of perceived intensity that were obtained before adaptation, the perceived intensity of E-EE3M2PA decreased during repeated exposures to the odorant (adaptation). There also was a significant decrease in the perceived intensity of mercaptoethanol during exposure to E-EE3M2PA (cross-adaptation).

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