Succinate esters

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a httlo reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl succinate in the presence of potassium [Pg.919]

Butanediol. 1,4-Butanediol [110-63-4] tetramethylene glycol, 1,4-butylene glycol, was first prepared in 1890 by acid hydrolysis of N,]S3-dinitro-l,4-butanediamine (117). Other early preparations were by reduction of succinaldehyde (118) or succinic esters (119) and by saponification of the diacetate prepared from 1,4-dihalobutanes (120). Catalytic hydrogenation of butynediol, now the principal commercial route, was first described in 1910 (121). Other processes used for commercial manufacture are described in the section on Manufacture. Physical properties of butanediol are Hsted in Table 2. 

Condensation with Aldehydes and Ketones. Succinic anhydride and succinic esters in the presence of different catalysts react in the gas phase with formaldehyde to give citraconic acid or anhydride and itaconic acid (94—96). Dialkyl acyl succinates are obtained by reaction of dialkyl succinates with C 4 aldehydes over peroxide catalysts (97). 

Succinic esters condense with aldehydes and ketones in the presence of bases, eg, sodium alkoxide or piperidine, to form monoesters of alkybdenesuccinic acids, eg, condensation of diethyl succinate with acetone yields ethyl 2-isopropyhdenesuccinate (eq. 3). This reaction, known as Stobbe condensation, is specific for succinic esters and substituted succinic esters (98,99). 

Cellulose esters of aromatic acids, aUphatic acids containing more than four carbon atoms and aUphatic diacids are difficult and expensive to prepare because of the poor reactivity of the corresponding anhydrides with cellulose Httle commercial interest has been shown in these esters. Of notable exception, however, is the recent interest in the mixed esters of cellulose succinates, prepared by the sodium acetate catalyzed reaction of cellulose with succinic anhydride. The additional expense incurred in manufacturing succinate esters is compensated by the improved film properties observed in waterborne coatings (5). 

KNOEVENAGEL OOEBNER STOBBE Condensation Base catalyzed aldol condensation of aldehydes or ketones with an activated methylene group of a malonic ester (Knoevenagel Doebner) or a succinic ester (Stobbe)... 

Methylindole and acetylenedicarboxylic acid is reported to give two unidentified products, but with the dimethyl ester the crs and trans (61) adducts were obtained. It was suggested that the major product had the trans configuration but this was not proved. Hydrogenation of both adducts gave the corresponding succinic ester, which was also obtained from 2-methylindole and maleic anhydride, followed by esterification. 

Succinaldehyde, 7, 41 Succinic acid, 5, 10, 8, 13 Succinic ester (ethyl), 5, 10 Sulfonation, with chlorosulfomc acid, 5, 3... 

You probably came up with the suggestion that by using an esterase which selectively hydrolyses the succinate ester of L-menthol, you would be able to isolate L-menthol from the mixture. This is in essence the way the process is carried out commercially. We can represent this process by ... 

Table 4 gives a rough overview of the variation possibilities in these product classes. Products with a second succinic ester moiety gained particular importance in various application fields [56,57]. 

Fatty alcohol Succinic esters of Disodium salts of ... 

In Entry 5, the chirality at an alkylated succinate ester is maintained and a 9 1 dr favoring the anti product is achieved, based on a preferred orientation relative to the branched substituent. 

Silica or porous glass is usually used as the solid phase in oligonucleotide synthesis. The support is functionalized through an amino group attached to the silica surface. There is a secondary linkage through a succinate ester to the terminal 3 -OH group. 

The possibility exists that the acid used in hydrolysis could catalyze the hydrolysis of the succinic ester group in the middle of the telechelomer itself. Even though NMR ( H and C) cannot easily eliminate this possibility, we have evidence that such a hydrolysis did not take place. For instance, hydrolysis should result in the formation of poly(pivalolactone) which is insoluble both in methylene chloride and water, but no insolubles were evident. Also, the Gel Permeation Chromatograms do not show impurities in the product. 

With respect to macromolecular drug-carrier approaches, the linear polysaccharide poly a-l,6-maltotriose (pullulan -OH) was combined with l-aminopropan-2-ol via the succinate ester in the following way [1613... 

A basic ionic liquid, l-methyl-3-butylimidazolium hydroxide ([bmIm]OH) and l-butyl-3-methyl-methylimidazolium tetrafluoroborate ([bmim]BF4), has been introduced as a catalyst and reaction medium for the Markovnikov addition of imidazoles 116 to vinyl esters 115 under mild conditions to give imidazoesters 117 <06JOC3991 06TL1555>. A series of (nitroimidazolyl)succinic esters and diacids were prepared from the Michael-type addition of the nitroimidazole to the a,P-unsaturated ester <06S3859>. 

DPP pigments are synthesized by reacting succinic ester with benzonitriles in the presence of alcoholate in the corresponding alcohol for base catalysis. Originally starting from sodium methylate/methanol an important step toward a significantly improved yield was achieved by reaction of succinic tert.-alkylester in sodium tert.-alkylalcoholate/tert.-alkylalcohol. 

EM for cyclization of succinamic acid assumed equal to that for cyclization of succinic esters (Table A.2 see text). Direct rate comparisons give EM s for substituted succinamic acids at 25°. No corrections for pX,... 

It then remains to remove protecting groups and release the product from the support. All of these tasks, except for the removal of the dimethoxytrityl group, are achieved by use of a single deprotection reagent, aqueous base (ammonia). The cyanoethyl groups are lost from the phosphates by base-catalysed elimination, and amide protection of the bases is removed by base-catalysed hydrolysis. The latter process also achieves hydrolysis of the succinate ester link to the support. 

Because the liquid phase enthalpy of formation of the corresponding t-butyl methyl succinate ester is available, —950.9 3.0 klmol", the enthalpy of reaction 16 can be calculated. The result, —72.8 3.9 kJ mol , is nearly the same as that for the esters and peresters above, —70.3 8.1 kJmol. ... 

Metal Hydrides. Metal hydrides generally react readily with acetylenes, often by an insertion mechanism. Cobalt hydrocarbonyl gives complicated mixtures of compounds with acetylenes. The only products which have been identified so far are dicobalt hexacarbonyl acetylene complexes (34). Greenfield reports that, under conditions of the hydroformy lation reaction, acetylenes give only small yields of saturated monoaldehydes (30), probably formed by first hydrogenating the acetylene and then reacting with the olefin. Other workers have identified a variety of products from acetylene, carbon monoxide, and an alcohol with a cobalt catalyst, probably cobalt hydrocarbonyl. The major products observed were succinate esters (74,19) and succinate half ester acetals (19). 

Alkenes can be converted to succinic esters by reaction with carbon monoxide, an alcohol, and palladium chloride in the presence of mercuric chloride.1,12 The addition is mostly syn. In similar reaction, both terminal and internal alkynes can be converted to esters of maleic acid. 

Furans have been prepared from 1,4-dialdehydes, usually in the more accessible acetal form by acid catalyzed ring closure. Using this approach, furan-3,4-dicarboxyIic acid has been obtained in 70% yield as the ester from 2-(dialkoxymethyl)-l-formyl succinic ester (54JOC1671). c/s-2-Butene-l,4-diol on oxidation to the monoaldehyde is cyclized to furan (61 ACSll77). The acetals (83) and (84) have been converted to the corresponding furan... 

Substituted succinic esters are formed coincidentally with the meth-oxy esters, although in relatively smaller amounts. ds-2-Butene gives a mixture of diesters, meso and d,1-pair, while trans-2-butene yields only the d,l enantiomers. By the addition of sodium acetate, conditions which preclude prior isomerization of the olefins are obtained the diesters are the exclusive products, and the dicarbonylation is stereospecifically cis. The carbonylation of trans-2-butene, which is at least seven times faster than that of the cis isomer, gives exclusively the d,l-succinic ester while m-2-butene gives only the meso diastereomer. These results are consistent with the mechanism shown for cw-2-butene (19) (see top of next page). 

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