Dicarboxylic acid diester

Diesters and even triesters have been converted to bis- and tris(cyclopropanol)s, respectively. Dimethyl succinate gave the bis (cyclopropanol) derivative 17 in 80% yield, while triethyl trans-cyclopropanetricarboxylate (18) yields the tris (cyclopropanol) 19 (90%) (Scheme 11.4 selected examples in Table 11.2) [77,78], Higher homologous dicarboxylic acid diesters are likewise smoothly converted with ethylmagnesium bromide in the presence of Ti(OiPr)4 to provide the corresponding bis (cyclopropanol) s [71,78]. 

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... 

Fig. 12 Lipase-catalyzed polycondensation of 1,6-hexanedithiol with dicarboxylic acid diesters to give polythioesters [43]...

Fig. 15.20. [4+2]-Cycloaddi-tion between l-(di methyl-amino)- , 3-butadiene and cis-dicyanoethene dicarboxylic acid diester II explanation of the inversion of configuration in the dienophile moiety.

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... 

Table 11.7-1. Pig liver esterase-catalyzed enantiotopos-differentiating hydrolysis of prochiral cyclic dicarboxylic acid diesters in aqueous solution.

Table 11.1-12. Lipase-catalyzed enantiotopos-differentiating hydrolysis of prochiral acyclic and cyclic dicarboxylic acid diesters in aqueous solution (CCL Candida cylindracea lipase, PPL pig pancreas lipase, PSL Pseudomonas sp. lipase, CVL Chromobacterium viscosum lipase,...

A limited number of acyclic and cyclic prochiral dicarboxylic acid diesters were found to be good substrates for hydrolysis catalyzed by lipases (Table 11.1-12). Notable examples which give a good illustration of the potential of hydrolases as well as of the trial and error approach one relies on to a certain extent are the dithio acetal derivative 9 and the fluoro alkyl malonates 1-8. The dithio monoester 9 is obtained with different lipases with high enantioselectivities and yields despite its remote chiral center. Candida cylindracea lipase is the enzyme of choice for the synthesis of fluoro alkyl malonates with small alkyl groups. An astonishing observation was... 

Prochiral and meso-compounds have been widely transformed into chiral products through transesterification reactions as shown with the acylation of diols (Fig. 14,1 and II). In transesterification, the prochiral or meso-substrate can also be a dicarboxylic acid diester. Common to such compounds is a plane of symmetry... 

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