Diesters reaction with dicarboxylic acids

A closely related reaction is equilibration of a dicarboxylic acid and its diester to produce monoesters The reaction of a carboxylic acid with ethyl acetate, in the presence of NaHS04 Si02, was shown to give the corresponding ethyl ester. Iodine catalyzes the transesterification of p-keto esters. 

Later, polythioesters were prepared by the polycondensation of dicarboxylic acid diesters with a dithiol [43] (Fig. 12). Initially, various lipases were screened in the polycondensation between diethyl adipate and hexane-1,6-dithiol at 120 °C in the presence of molecular sieves. The use of 70wt% immobilized CALB as catalyst proved to be efficient in these polycondensation reactions with dicarboxylic acid... 

Dehydrohalogenation sometimes leads to cyclization which gives cycloalkanes or heterocycles. The fluorinated diester 1 has proved to be a convenient source of polyfluoroalkylated cyclopropanes. Reaction of 1 with aqueous potassium hydroxide gives 2- HA //-hepta-fluorobutyl)cyclopropane-l, 1 -dicarboxylic acid (2) in quantitative yield.120 The diethyl ester 3 ot this acid is obtained in a yield of 87% by the reaction of 1 with sodium ethoxide in anhydrous ethanol.120... 

The acid-catalysed reaction of a dicarboxylic acid with an excess of alcohol yields the diester. However, the process may be adapted to prepare acid esters of dicarboxylic acids by using molar proportions of the diacid and alcohol (e.g. methyl hydrogen adipate, Expt 5.147). Alternatively the acid ester may be prepared by subjecting the diester to controlled partial hydrolysis with one molar proportion of potassium hydroxide. 

Most commercially manufactured esters are produced by reacting an alcohol with a carboxylic acid. This esterification reaction is reversible and is commonly referred to as a condensation reaction, since water is a by-product. The type of ester under consideration is referred to as a diester and can be produced by reacting a monohydric alcohol with a dicarboxylic acid. For example ... 

Asymmetrization of a prochiral dicarboxylic acid diester catalyzed by lipases, where the stereo center of the product is located on the acyl side, becomes a single-step process because the polar carboxylic acid and/or amide formed are not well accepted as substrates by the Upase. One example is the enantioselective hydrolysis or ammonolysis of diethyl 3-hydroxyglutarate, as shown in Scheme 7.4, a reaction which leads to the formation of a precursor for the important chiral side chain of atorvastatin, lipitor [40, 41]. The S-enantiomer was formed with high e.e. (98%), but unfortunately this is the undesired enantiomer for the production of the pharmaceutically important product. Only a-chymotrypsin gave a predominance of the... 

In addition to cyclic allylic substrates, malonate nucleophiles have been used in reactions with both symmetrical" and unsymmetrical" acyclic systems, and with geminal dicarboxylates. Malonates and Meldrum s acid have also been used as nucleophiles in the desymmetrization of meso diesters. 

Egyptian researchers - treated the 2-styryl-4-quinazolinones 132 with maleic anhydride and iV-phenylmaleimide and obtained the Diels-Alder adducts 133. The latter were hydrolyzed with alcoholic sodium hydroxide to the pyrido[l,2-a]quinazoline-l,2-dicarboxylic acids 134 (R = H). The di-carboxylic acids 134 (R = H) and their diesters (R = Et) were also obtained in the reaction of the 2-styryl-4-quinazolinones 132 with maleic acid or diethyl maleate. 

Polyamides such as Nylon are formed from dicarboxylic acids and diamines. Polyesters such as Dacron are formed from the reaction of dicarboxylic acids or diesters with dialcohols. 

Starch carbonate diesters were formed by reaction of starch with alkylene carbonates under diminished pressure at 100-140 °C 2002 The products were proposed as surgical dusting powders. Another method involved dimethyl sulfoxide as the reaction medium, triethylamine as the catalyst, and trans-carbonates of glycosides as the acylating agents. Thionocarbonates were used similarly. The degree of substitution was O.4.2003 Another method involves 1-acyl I, I -carbodiirnidazole or dicarboxylic acid imidazolides at pH 8.O.2004... 

When either L-tartaric acid esters la,b or D-tartaric esters 2a,b are treated with benzaldehyde under acidic catalysis with Deair-Stark removal of generated water, good to excellent yields of either (4i ,5i )-(330) or (45, 5 S)-2-phenyl-l,3-dioxolane-4,5-dicarboxylates (331) are obtained [115,116]. Acetal exchange, which involves reaction of the tartaric diesters with benzaldehyde dimethyl acetal in the presence of an acid catalyst, is also an excellent protection method [117]. 

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