4-pentenoic acid chloride

Cyclobutanones 131, obtained easily by the 2 + 2 cycloaddition of olefines and ketenes, subjected to Bayer-Villiger-oxidation undergo ring enlargement to the y-lactones 128 of interest. Reaction scheme 83 describes such a reaction, starting from isobutene and Q-dichloro-4-pentenoic acid chloride 132. 

A mixture of 5 g. of anhydrous zinc chloride (Note 1) and 280 g. (2.00 moles) of 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid /9-lac-tone 2 is placed in a 500-ml. three-necked flask equipped with a sealed stirrer (Note 2), a coarse fritted-glass gas-dispersion thimble, a thermometer immersed in the liquid, and an air-cooled reflux condenser (Note 3). The outlet of the condenser is connected to a bubble counter filled with concentrated sulfuric acid this in turn is vented to the atmosphere through a water scrubber. The flask is immersed in an ice bath, and stirring is started. When the temperature of the mixture is about 10°, anhydrous hydrogen chloride is introduced through the gas-dispersion tube... 

Structurally similar photochromic maleic anhydride derivatives 177 with a similar reaction mechanism were prepared by Irie (05CL64) by a one-pot synthesis from 2-methoxybenzothiophene, oxalyl chloride, and pentene-3-carboxylic acid (3-pentenoic acid) in dichloromethane in the presence of triethylamine at 5°C for 2 h according to Scheme 54. 

Allyl bromide 1-Propene, 3-bromo- (106-95-6), 76, 60, 221 Allyl chloride 1-Propene, 3-chloro- (107-05-1), 77, 254 l ALLYLGLYCINE 4-PENTENOIC ACID, 2-AMINO-, (R)- (54594-06-8), 76, 57 Allylic alcohols, enantioselective cyclopropanation, 76, 97 ALLYLINDATION, 77, 107... 

Trimethylacetyl chloride (0.065 mol) was added to 4-methyl-2-pentenoic acid (0.06 mol) and triethylamine (0.187 mol) dissolved in 200 ml THF at —20°C. After 1 hour the mixture was treated with LiCl (0.55 mol) and (R)-(-)-4-phenyl-2-oxazolidinone (0.05 mol) and a thick suspension formed, which was stirred 20 hours at ambient temperature. The suspension was filtered and the filtrate concentrated. The residue was recrystallized using hexane/EtOAc, 5 1, and the product isolated in 68% yield as a white solid. 

A variant of this process, studied by DuPont and DSM [32c], includes the hydrocarboxylation (hydroxycarbonylation) of butadiene with carbon monoxide and water this technology offers potential savings in raw material costs. The reaction primarily yields 3-pentenoic acid using a palladium/crotyl chloride catalyst system, with a selectivity of 92%. Further conversion of pentenoic acids by reaction with carbon monoxide and methanol and a palladium/ferrocene/phosphorous ligand catalyst has demonstrated a selectivity to dimethyl adipate of 85% the latter is finally hydrolyzed to AA. The main problem in this reaction is the propensity of pentenoic acid to undergo acid-catalyzed cyclization to y-valerolactone one way to circumvent the problem is to carry out the hydrocarboxylation of pentenoic acid using the y-valerolactone as the solvent. 

The stabilized cyclic olefin insertion product explains why the reaction stops with the insertion of only one ethylene group. The carboxylation product of crotyl chloride, 3-pentenoic acid, and 2,6-octadiene (from the coupling of two crotyl chloride molecules together) also forms. 

Mercaptovaleric acid 44 Thioacetic acid (25 g) is added to 2-pentenoic acid (25 g), and next day a crystalline substance (39.5 g m.p. 43-45°) is obtained by distillation at 133-1340/2mm. This acetylthio compound is hydrolysed by treatment with sodium hydroxide (25 g) in water (200 ml) and on the following day the solution is acidified with concentrated sulfuric acid (60 g) in water (60 ml) and extracted with ether. The extracts are dried by calcium chloride, whereafter distillation affords the 2-mercaptovaleric acid, b.p. 108-110°/4 mm (22.5 g). 

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]. 

To a 750-mL flame-dried, five-necked flask equipped with a condenser, addition funnel, stirrer, thermometer, and nitrogen inlet were added 13.0 g ethyl 3-methyl-2-butenyl sulfide (0.10 mol), 7.2 g activated zinc (0.11 mol), and 200 mL anhydrous ether. Under stirring, a solution of 11.5 mL trichloroacetyl chloride (18.5 g, 0.105 mol) in 100 mL anhydrous ether was added to the suspension over a period of 4 h. After that, an additional 3.5 g activated zinc (0.05 mol) was added to the flask, and the mixture was stirred for an additional hour. Pentane (200 mL) was added to precipitate the zinc salts, and the solution was decanted from the residue. The residue was washed twice with ether-pentane (50 mL), and the combined solutions was washed successively with water, a cold solution of 10% NaHCOs, and brine and then dried over MgS04. Upon removal of solvent under vacuum, 17.2 g of crude ethyl thioester of 2,2-dichloro-3,3-dimethyl-4-pentenoic acid was obtained which was further purified by vacuum distillation to give 9.1 g product, in a yield of 38% (should be >38%), b.p. 66°C 0.25 mmHg. 

In their total synthesis of (-i-)-ophiobolin in 1989, Kishi et al. found that treatment of a cyclopentenyl ester under the typical Ireland conditions gave principally C-silylated ester [63]. Heating of a C-silyl ester (prepared by acylation using a C-silyl acyl chloride) at 230 °C resulted in a 1,3-Brook rearrangement followed by an Ireland-Claisen rearrangement to give the desired product as a 6 1 ratio of isomers at C2 of the pentenoic acid (Scheme 4.63). The major product could have arisen through either a chair transition state of the Z-sUyl ketene acetal or a boat transition state of the E-silyl ketene acetal. 

When the mixed anhydride between 4-ethyl-4-pentenoic acid and pivalic acid (prepared using pivaloyl chloride on the pentenoic acid) was treated with the lithium salt of (i )-4-benzyl-2-oxazolidinone an imide was formed where one (the bottom as drawn) face is encumbered by the bulky benzyl group. Thus, cyanoeth-ylation occurred with diastereoselectivity, and a single isomer was isolated. Reduction of the imide with sodium borohydride (NaBU,) then resulted in the formation of the primary alcohol, and the latter was protected as the f-butyldiphenylsilyl (TBDPS)... 

When thien-2-ylacetic acid was subjected to the abovementioned reaction coti-ditions, similar ring opening was observed and the products consisted of (Z)-3-benzylthio-3-hexenoic acid and (Z)- and ( )-3-benzylthio-2-hexenoic acid with the ratio of 84 12 4. As illustrated in Scheme 127, the Birch reduction of 2-(thien-2-yl) propanoic acid with five equivalents of sodium in liquid ammonia in the presence of ethanol and a subsequent treatment with ammonium chloride and benzyl bromide led to the formation of (Z)-3-benzylthio-2-methyl-3-hexenoic acid in the yield of 63%. Additionally, under similar reaction conditions, 2-(thien-2-yl)hexenoic acid and 2-(thien-2-yl)-4-pentenoic acid also created the corresponding (Z)-3-benzylthio-2-butyl-3-hexenoic acid and (Z)-2-allyl-3-benzylthio-3-hexenoic acid with 77 and 76% yields, respectively [140]. 

Carbonyiation of butadiene gives two different products depending on the catalytic species. When PdCl is used in ethanol, ethyl 3-pentenoate (91) is obtained[87,88]. Further carbonyiation of 3-pentenoate catalyzed by cobalt carbonyl affords adipate 92[89], 3-Pentenoate is also obtained in the presence of acid. On the other hand, with catalysis by Pd(OAc)2 and Ph3P, methyl 3,8-nonadienoate (93) is obtained by dimerization-carbonylation[90,91]. The presence of chloride ion firmly attached to Pd makes the difference. The reaction is slow, and higher catalytic activity was observed by using Pd(OAc) , (/-Pr) ,P, and maleic anhydride[92]. Carbonyiation of isoprcne with either PdCi or Pd(OAc)2 and Ph,P gives only the 4-methyl-3-pentenoate 94[93]. 

Chlorostannate ionic liquids have been used in hydroformylation reactions [23], Acidic [bmimjCl-SnCb and [l-butyl-4-methylpyridinium]Cl-SnCl2 were prepared from mixing the respective [cation]+ Cl with tin(II)chloride in a ratio of 100 104, much in the same way that the chloroaluminates are made (see Chapter 4). Both these chlorostannate ionic liquids melt below 25 °C. Addition of Pd(PPh3)2Cl2 to these chlorostannate ionic liquids leads to a reaction medium that catalyses the hydroformylation of alkenes such as methyl-3-pentenoate as shown in Scheme 8.9. The ionic liquid-palladium catalyst solution is more effective than the corresponding homogeneous dichloromethane-palladium catalyst solution. The product was readily separated from the ionic liquid by distillation under vacuum. This is an important reaction as it provides a clean route to adipic acid. 

Condensation of 2-chloro-A -pyrrolidinium chloride (prepared in situ from iV-benzylpyrrolidin-2-one 194 and phosgene) with f-butyl 3-oxo-4-pentenoate, followed by acid treatment under ultrasound irradiation condi-... 

The codimerization of a functional olefin with a non-functional olefin is an interesting possibility for the synthesis of longer-chain monofunctional products. One example is the rhodium or rutheniixm chloride catalyzed codimerization of methyl acrylate with ethylene yielding linear monounsat-urated acids [48]. The main product is methyl-3-pentenoate (47%), but also esters of acids containing seven and nine carbon atoms were isolated in yields of 12 and 9%, respectively (Equation 49). 

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