Pyridine acetic acid esters

Method E, which assumes the N(7)-C(7a) bond formation in the cyclization step, is also rarely used in the synthesis of thienopyridines. For example, the method (1997H255, 1998JMC(E)33, 1998PS21) for the preparation of 4-oxo-4,7-di-hydrothieno[2,3-Z>]pyridine-5-carboxylic acid esters 54 is based on intramolecular /V-nucleophilic substitution of (E/Z)-aminomethylene derivatives of (2,5-dichloro-3-thenoyl)acetic acid esters 52 in the presence of a strong base. Esters 52 and products of their alkaline hydrolysis 56 have an antibacterial action the influence of the substituents on the biological activity of the resulting compounds was studied. 

Protective group for nucleosides. Stepwise synthesis of oligonucleotides utilizing 2-cyanoethyl phosphate (1, 172-173) requires protection of the 3 -hydroxyl group which can be cleaved under essentially neutral conditions, since a methoxy-trityl ether is sensitive to acid and a /3-cyanoethyl phosphoric ester is sensitive to alkali. The /3-benzoylpropionyl group meets these requirements, since it is quantitatively cleaved by dilute solutions of hydrazine hydrate in pyridine-acetic acid. The esters are prepared by condensation with DCC (dicyclohexylcarbodiimide). Definitive paper R. L. Letsinger and P. S. Miller, Am. Soc., 91, 3356 (1969)... 

Two highly unusual procedures for the preparation of trialkyl phosphates have been described. In the first, alkanes are made to react with trimethyl phosphite in a medium consisting of FeCl2.4H2O Zn(0) O2 in pyridine - acetic acid. The essential reaction appears to be one of Fe(II)-catalysed oxidation of the tervalent phosphorus ester by an alkyl hydroperoxide to afford an alkyl dimethyl phosphate. In the second procedure, described in considerable detciil, a Cu(II) catalyst aids in the interaction of red... 

On the other hand, 6-esters of D-glucose and Tyr-terminal peptides rearrange in pyridine-acetic acid (but not in dry methanol, see Seetion n.l.b.vui later) into stable bicyclic D-fiuctosamine structures (26) (Scheme 10). The length and rigidity of the bridging peptide, however, defines its ability to form the Amadori rearrangement products and their tautomeric equilibria in solutions. ... 

Acid anhydrides react with alcohols to form esters The reaction may be carried out in the presence of pyridine or it may be catalyzed by acids In the example shown only one acyl group of acetic anhydride becomes incorporated into the ester the other becomes the ac yl group of an acetic acid molecule... 

Figure 3 shows the production of acetaldehyde in the years 1969 through 1987 as well as an estimate of 1989—1995 production. The year 1969 was a peak year for acetaldehyde with a reported production of 748,000 t. Acetaldehyde production is linked with the demand for acetic acid, acetic anhydride, cellulose acetate, vinyl acetate resins, acetate esters, pentaerythritol, synthetic pyridine derivatives, terephthaHc acid, and peracetic acid. In 1976 acetic acid production represented 60% of the acetaldehyde demand. That demand has diminished as a result of the rising cost of ethylene as feedstock and methanol carbonylation as the preferred route to acetic acid (qv). 

Mixed cellulose esters containing the dicarboxylate moiety, eg, cellulose acetate phthalate, have commercially useful properties such as alkaline solubihty and excellent film-forming characteristics. These esters can be prepared by the reaction of hydrolyzed cellulose acetate with a dicarboxyhc anhydride in a pyridine or, preferably, an acetic acid solvent with sodium acetate catalyst. Cellulose acetate phthalate [9004-38-0] for pharmaceutical and photographic uses is produced commercially via the acetic acid—sodium acetate method. 

Cellulose esters of unsaturated acids, such as the acetate methacrylate, acetate maleate (34), and propionate crotonate (35), have been prepared. They are made by treating the hydrolyzed acetate or propionate with the corresponding acyl chloride in a pyridine solvent. Cellulose esters of unsaturated acids are cross-linkable by heat or uv light solvent-resistant films and coatings can be prepared from such esters. 

In methanol, isoquinoline and the ester gave the benzo[fif]indolizine [(121), cf. Section II,D,3] while in ether the labile adduct, tetra-methyl llbH-benzo[a]quinolizine-l,2,3,4-tetracarboxylate (122) was obtained. The labile adduct is much less easily isoraerized than the 9-methyl-9aH-quinolizines derived from pyridines (Section III,F,1) but with boiling xylene or, better, with sulfuric-acetic acids the cor-... 

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