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Pyridyl esters, hydrolysis

Results from CoMFA studies have been compared with those from Hansch analyses [38, 1019 — 1023] and the minimal topological difference (MTD) method [1024]. Examples for the comparison of Hansch equations with CoMFA studies are e.g. the papain hydrolysis of N-(X-benzoyl)glycine pyridyl esters (60) (eqs. 204, 205 Zn = PLS component n of the corresponding field compare chapter 7.1) [1019, 1020], the emulsin-catalyzed hydrolysis of phenyl-P-D-glucosides [1020], the mutagenic activities of substituted (o-phenylenediamine)platinum dichlorides [1020], dihydrofolate reductase (DHFR) inhibition [1020], and some other biological activities [38, 1021—1023]. [Pg.169]

Hydrolysis of ethyl 9-fluoro-10-(4-methylpiperazino)-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylate in a boiling mixture of AcOH and 35% HCl afforded 7 HCl (97USP5703233). That of (3S)-3-methyl-10-(2,6-dimethyl-4-pyridyl)-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- e]-l,4-benzothiazine-6-carboxylate gave the 6-carboxylic acid (OOMIPIO). 7-Oxo-2,3-dihydro-7//-pyrido[l,2,3- fe]-l,4-benzothiazine-6-carboxylic acid was obtained from its ethyl ester by alkalic hydrolysis in 20% yield (99AP19). [Pg.294]

The quinolizine derivative 276 was obtained through a Friedel-Crafts acylation reaction onto the C-3 indole position of 275. This precursor was obtained by a sequence comprising a Fischer cyclization leading to 5-methyl-2-(2-pyridyl)indole 274, catalytic hydrogenation, N-alkylation with ethyl bromoacetate, and hydrolysis of the ester group (Scheme 59) <1999FA479>. [Pg.41]

Sulfo-LC-SMPT is not as stable as SMPT. The sulfo-NHS ester is more susceptible to hydrolysis in aqueous solutions and the pyridyl disulfide group is more easily reduced to the free sulfhydryl. Stock solutions of sulfo-LC-SMPT may be prepared in water, but should be used immediately to prevent loss of amine coupling ability. [Pg.79]

Dissolve a protein or macromolecule containing primary amines at a concentration of 10 mg/ml in 50 mM sodium phosphate, 0.15 M NaCl, pH 7.2. Other non-amine-containing buffers such as borate, HEPES, and bicarbonate also may be used in this reaction. Avoid sulfhydryl-containing components in the reaction mixture as these will react with the pyridyl disulfide end of SPDP. The effective pH for the NHS ester modification reaction is in the range of 7-9, but hydrolysis will increase at the higher end of this range. [Pg.280]

Several studies on intramolecular catalysis of the solvolysis of phosphate esters have been reported. The larger hydrolysis rate of the zwitterion of 8-hydroxyquinoline phosphate (20) compared with that of pyridyl 3-phosphate (21) was attributed, on the basis of the kinetic isotope effect, to intramolecular general acid catalysis. A similar general acid catalysis by the hydroxy-group seems to operate in the (3-hydroxy-2-pyridyl)methyl phosphate dianion (22), which hydrolyses faster than either the monoanion or the neutral molecule. From a study of 4- and 5-substituted derivatives of salicyl phosphate (23) it is suggested that the negligible solvent isotope effect is inconsistent with preliminary proton transfer, and that here also intramolecular general acid catalysis by the... [Pg.122]

A simple synthesis of y-aminoalkylphosphonic acids (77) involves addition of a nitroalkane to vinylphosphonic esters, followed by catalytic hydrogenation. j3-Aldehydophosphonic acids (78) are conveniently prepared by acidic hydrolysis of the readily accessible j3-alkoxyvinyl-phosphonates. Oxidation of (2-pyridyl)methyl phosphonic acid (79) with... [Pg.132]

Under hydro(solvo)thermal conditions, Cd and Zn coordination networks ean be obtained by reactions of metal salts with cyanopyridine or pyiidinecarboxaldehyde. Cyano-, carboxal-dehyde-, and ester-substituents slowly hydrolyze to form corresponding earboxylie acid facilitating network formation. For instance, bis[4- 2-(4-pyridyl)ethenyl benzoato]-Zn° and Cd with eightfold diamondoid network structures were obtained by slow hydrolysis of (E)-4-(4-cyanos-tyryl)pyridine under hydro(solvo)thermal conditions (3-D diamondoid net Scheme 6a). ... [Pg.256]

During an exploration of practical syntheses of a GnRH antagonist, Farr et al. examined two key substrates for the Mitsunobu reaction.Both reactions were carried out at kilo-scale. Typically, four equivalents of the pyridyl ethanol 181 were required to drive the reaction to completion. Since the dinitrosulfonamide product 182 proved to be labile during the hydrolysis of the methyl ester, further exploratory work was carried out with the p-nitrosulfonamide 183. The nosyl group of the crude reaction product 184 was removed with thioglycolic acid. After an aqueous workup, the desired product 185 was obtained in 58% yield over three steps after recrystallisation from ethyl acetate. Eventually, this route was abandoned due to supply issues with the pyridyl ethanol and byproduct removal issues arising firom the Mitsunobu reaction and the nosyl deprotection. [Pg.714]

Sulphoximides having longer alkyl chains or quaternary ammonium functional groups that contain heterocyclic groups such as thiophenyl, furanyl, or pyridyl have been prepared. 5-Hexadecyl-5-phenyl-(or / -tolyl-)sulphoximides have been prepared and tested as surfactants for the hydrolysis of esters. ... [Pg.144]

The stereospecificity of the interactions of several spin-labelled substrates with cyclohexa- and cyclohepta-amyloses, as models for chymotrypsin, has been studied. Complexes of the cycloamyloses with 2,2,6,6-tetramethyl-4-oxy-pyridyl-1-oxide in aqueous solution were examined by e.s.r. spectroscopy the nitroxide function moved to a relatively hydrophobic environment on binding to cyclohepta-amylose, and lost some freedom of rotation on binding to both cycloamyloses. The dissociation constant for the cyclohexa-amylose complex of the nitroxide is greater than that for the cyclohepta-amylose complex, consistent with measurements made on molecular models. In the hydrolysis of the asymmetric compound 3-carboxy-2,2,5,5-tetramethylpyrrolidyl-l-oxide 3-nitro-phenyl ester, catalysed by cyclohexa-amylose, enantiomeric specificity was observed in the acylation step but not in formation of the Michaelis complex , or on hydrolysis of the acylated cycloamylose intermediate. No differences were found in the e.s.r. spectra of solutions of the trapped acylcyclohexa-amylose intermediates derived from ( + )- and ( )-forms of the asymmetric nitroxide. The nitroxide function is less free to rotate in the acylcycloamylose intermediate than in the Michaelis complex and is not included in the cycloamylose cavity. [Pg.438]

Aliphatic nitriles react slowly with phenols and phenyl ethers in the presence of trifluoromethanesulphonic acid to give ketones after hydrolysis, in a variation of the Houben-Hoesch reaction. The crystalline complex of copper(i) triflate and benzene induces the acylation of aromatic substrates with selenol esters, affording a transition-metal mediated version of the Friedel-Crafts reaction. Aromatic carboxylic acids can be converted into symmetrical diaryl ketones in good yield by treatment of their 5-(2-pyridyl)thioesters with bis-(l,5-cyclo-octadiene)nickel [equation (15)]. In contrast to other methods for preparing symmetrical aromatic ketones, this method allows their preparation from a single starting material. [Pg.72]

Kinetic data for the alkaline hydrolysis of ethyl pyridine-carboxylates and their 1-oxides are summarized in Table 6.4, All the esters of pyridine monocarboxylic acids and their oxides are hydrolysed with lower activation energies than that associated with ethyl benzoate. The oxide esters are hydrolysed about 1,000 times faster than ethyl benzoate but rather because of high logio A values than because of low activation energies. In these reactions the mechanism is probably Bac in such processes E is reduced by increased electron-attracting power in the group attached to the ethoxy-carbonyl group. The expected order as between 3- and 4-pyridyl is observed, but 2-pyridyl falls out of place, perhaps for steric reasons. Clearly, in the... [Pg.321]

An alternative preparation of the amino acid amides on a laboratory scale is the alkylation of 7V-acetami domalonate esters followed by hydrolysis and amination of the amino esters. For instance, racemic allylglycine amide, methallylglycine amide, and P-(pyridyl)alanine amides are prepared by this method [19]. [Pg.26]


See other pages where Pyridyl esters, hydrolysis is mentioned: [Pg.357]    [Pg.440]    [Pg.242]    [Pg.258]    [Pg.455]    [Pg.306]    [Pg.282]    [Pg.282]    [Pg.248]    [Pg.431]    [Pg.242]    [Pg.36]    [Pg.156]    [Pg.1136]    [Pg.136]    [Pg.467]    [Pg.271]    [Pg.594]    [Pg.446]    [Pg.7209]    [Pg.202]    [Pg.190]    [Pg.213]   
See also in sourсe #XX -- [ Pg.322 ]




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Pyridyls

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