7-0-Acyl esters

To minimize the gradual embrittlement that can occur on aging of cyanoacrylate adhesives, plasticizers are added. Some of the materials, which have been used as plasticizers, include phthalates, phosphonates, acyl esters, succinates, and cyano-acetates. The use of allyl, methallyl, and crotyl phthalates is also claimed to improve thermal resistance properties in addition to plasticizing the adhesive [23]. 

Stereoisomerism in either the alkamine nucleus or the acyl residue has a considerable effect on the pharmacological action of the tropeines and cocaines. Differences in activity of tropine and i/i-tropine and their benzoyl derivatives have been mentioned already, and there seems to be a consensus of opinion that the i/i-cocaines (alkyl- or aryl- acyl esters of 0-ecgonine) are less toxic and more potent local anfesthetics than the corresponding cocaines, derived from 1-ecgonine. ... 

All the erythrophleum alkaloids examined in detail so far are of the same type, viz., acyl esters of either monomethylaminoethanol, e.g., erythrophleine and coumingidine or dimethylaminoethanol, such as cassaine or cassaidine. The acyl substituents are complex, yield 1 7 8-trimethylphenanthrene on selenium dehydrogenation, and contain at least one hydroxyl group, which may be acylated by an aliphatic acid, e.g., coumingine forms three components on hydrolysis. 

A strain of Acinetobacter calcoaceticus produces an unusual polysaccharide called emulsan. It is a complex polymer comprising about 15% fatty acyl esters and 20% protein. This structure enables it to act as an emulsifying agent, stabilising hydrocarbon/water emulsions at very low concentrations (0.1-1.0%). This property,... 

Water-soluble acylating esters sodium benzoylthioglycolate and benzoylsalicylate (Scheme 10.69). 

S.N. Dudd, R.P. Evershed, Unusual triterpenoid fatty acyl ester components of archaeological birch bark tars, Tetrahedron Letters, 40, 359 362 (1999). 

Complex lipids are acyl esters of an alcohol and contain a hydrophilic group. 

Low density lipoprotein (LDL) 78 10 45-50 20 20-25 Transport of cholesterol, mostly as the acyl ester, synthesized in the liver... 

The reduction of nitroarenes to azoxy compounds ArN=N(0)Ar is promoted by bismuth trichloride/powdered zinc427. Aromatic amines are formed in excellent yields in the reduction of nitroarenes with BH3/NiCl2428 or nickel boride429. Acyl, ester, amide and cyano groups are not affected. Reaction of the nitro compounds RCH2N02 (R = Ph, Bz... 

The activation under physiological conditions of a variety of other amino acyl esters of metronidazole was investigated the results presented in Table 8.9 are discussed here and in Sect. 8.5.5.2 [137]. This series contains the glycine ester, various V-substituted glycinates, two esters of /3-alanine and one of 4-aminobutyric acid. The glycine ester and its V-substituted analogues of relevance here were hydrolyzed relatively rapidly in plasma, the exception being the piperazinyl derivative discussed below. 

In a limited number of NRPSs, the final module terminates in a specialized C domain that catalyzes chain release through amide bond formation. Modules of this type are found in the synthetases involved in the biosynthesis of enniatin, vibriobactin, cyclosporin/ HC-toxin/ and PF1032A. Unlike TE termination, this method of chain release does not utilize an acyl-ester intermediate. Most likely, the chain termination precursor is presented to the C domain as an aminoacyl-5-PCP substrate. Most of these specialized C domains... 

Selected entries from Methods in Enzymology [vol, page(s)] Application in fluorescence, 240, 734, 736, 757 convolution, 240, 490-491 in NMR [discrete transform, 239, 319-322 inverse transform, 239, 208, 259 multinuclear multidimensional NMR, 239, 71-73 shift theorem, 239, 210 time-domain shape functions, 239, 208-209] FT infrared spectroscopy [iron-coordinated CO, in difference spectrum of photolyzed carbonmonoxymyo-globin, 232, 186-187 for fatty acyl ester determination in small cell samples, 233, 311-313 myoglobin conformational substrates, 232, 186-187]. 

Applications in infrared spectroscopy A and B bands, iron-coordinated CO, 232, 186-187 application to allosteric mechanisms, 249, 566 bacteriorhodopsin, 246, 9, 380-381 caged compounds, 246, 6, 520-521 DNA [base pair formation, 246, 506 conformation, 246, 506-507 denaturation thermodynamics, 246, 506 ligand interactions, 246, 6, 507 sample requirements, 246, 506] fatty acyl ester determination in small cell samples, 233,... 

In the case of the monoester 591, the same reaction as shown in Scheme 155, but using benzoyl chloride as electrophile, yielded the corresponding acylated ester 592 . ... 

These experiments with acyl esters and the intrinsic primary-amine nucleophiles of polyethylenimines thus illustrate that this polymer with binding domains for substrate provides a suitable framework for achieving enhanced reaction rates in aqueous solution. Aminolysis, however, is... 

The polyethylenimines are also effective in the cleavage of nitrophenyl-sulfate esters and nitrophenylphosphate esters. These have not yet been studied as extensively as the acyl esters, but interesting kinetic accelerations are already apparent. Nitrocatechol sulfate, for example, is very stable in aqueous solution at ambient temperature. In fact, even in the presence of 2 M imidazole no hydrolysis can be detected at room temperature. At 95°C in the presence of 2 M imidazole cleavage is barely perceptible. In contrast, a modified polyethylenimine with attached imidazole groups cleaves the sulfate ester at 20°C.34 Some kinetic parameters are compared in Table VI. It is obvious that accelerations of many orders of magnitude are effected by the polymer. 

---