Pyridine-containing esters

The reaction of pyridines with alkynic compounds provides a useful synthesis of indolizines containing ester groups in the five-membered ring (78AHC(23)263). 

Pentadienoates.1 Half esters of malonic acid react with a,(3-enals in pyridine containing dimethylaminopyridine to form these diunsaturated esters, with generally high (2E)-selectivity. 

Olefin-containing esters of pyridine-3,5-dicarboxylic acid are able to form macrocycles using a ring-closing metathesis reaction if the pyridine was protected with complexing Pt. The method was applied to 69- and 75-membered macrocycles <03ZOR449>. An example of a 17-membered ring formation is shown below. 

Stannic chloride has been attached to monomers 21 containing ester (21a), carbazole (21b), pyrrolidone (21c), nitrile (21d) and pyridine (21d) moieties. The polymeric ligands were prepared by copolymerization of styrene, divinylbenzene and functional monomers such as methyl methacrylate, A -vinylcarbazole, Af-vinylpyrrolidone, acrylonitrile and 4-vinylpyridine [33], These polymers were treated with stannic chloride in chloroform to afford the corresponding polymer-supported stannic chloride complexes (Eq. 8). These polymeric complexes have been used as catalysts for such organic reactions including esterification, acetalization, and ketal formation. These complexes had good catalytic activity in the reactions and could be reused many times without loss of activity. Their stability was much better than that of plain polystyrene-stannic chloride complex catalyst. 

Liquid uronititic iiiniiic i. for example aniline or lsiH iiinolinc, ofcen become badly discolored on storage us Ihc rcsull of air oxidation. Distillation from a pinch of zinc dust affords tdmost water-clear liquid. Kuhn and Winterstein" found that the violet carotinoid ester-acid bixin can be reduced very smoothly to its yellow dihydride with zinc dust in pyridine containing a small amount of acetic acid. Thus on addition of... 

Over the past few years several biocides have been converted to monomers containing ester, amide, or ether functions which bind the biocide and the polymerization of these monomers was studied.12-16 fhe biocides examined included pentachlorophenol, 1,12-16 8-hydroxyquinoline,2,12,14-16 3 4, 5-tribromosalicy-lanilide,3,12, 14-16 o-benzyl-p-chlorophenol,4,14-16 salicy-lanilide,5,12 2-(4 -thiazoyl)benzimidazole,6,12 and 2-mercapto-pyridine-N-oxide, 7. 

Other companies (Cilag AG and R. W. Johnson) required the pyridine-containing P-amino acid 11 or, to be more accurate, the ester dihydrochloride4 12. This combination of acidic and basic functional groups offers a wide choice of resolving agents. 

Other compounds containing ester functions are present in sections 5.H (phenols), 5.1 (furans), 5.J (thiophenes), 5.N (pyridines), 5.P (nitrogen compounds) and 5.Q (sulfur compounds). 

Studies on the rates and mechanisms of reduction of [Co(NHj)5 Lf species, where L = pyridines, pyrazines, fused bipyridyls and bipyridyls containing ester, acid, nitrile and amide substituents, by metal reductants (Ci, Eu ) continue to be advanced by Gould and coworkers. For this class... 

Nicotinic acid was first identified as an essential dietary supplement in 1937. It can be found in an active form as either free nicotinic acid, the amide derivative or bound to the pyridine-containing nucleotides (nicotinamide adenine dinucleotide (NAD) and the corresponding phosphate ester (NADP)). 

Lie Ken Jie, M.S.F., and Pasha, M.K. (1996) Synthesis of Novel Piperideine- and Pyridine-Containing Long-Chain Fatty Ester Derivatives from Methyl Isoricinoleate, J. Chem. Soc. Perkin Trans. 1,12,1331-1332. 

The highly functionalized imidazole 3 can be polymerized by active phosphite ester methods [4] to afford the A-B polyamide. The monomer is dissolved in a mixed solvent system of N-methylp3n rolidinone and pyridine containing dissolved lithium chloride. Upon addition of triphenyl phosphite, the reaction immediately takes on a yellow color. During the course of the polymerization, the color increases in intensity until the pol5rmerization mixture appears black. The products are isolated as fine yellow powders by precipitation in methanol followed by a methanol wash. 

The methyl ester of DL-phenylalanine was recovered from its hydrochloride salt and was reduced with LiAlH4 to 3-phenyl-2-amino-l-hydroxypropane. Then 1.0 g such an alcohol (6.6 mmol) was dissolved in 20 mL cold pyridine containing 2.9 g benzenesulfonyl chloride (16.0 mmol) the solution was held at 5°C overnight. Ice was added (50 g) followed by cold 4 N HCl. The resulting solid was collected and crystallized from 95% ethanol to give 1.9 g 3-phenyl-2-benzenesulfonamido-l-(benzene-sulfonyloxy)propane, in a yield of 66%, m.p., 104.5-106.5°C. 

A number of new routes to a-methylene esters (121) have been developed (see also ref. 110). Perhaps the simplest involves the treatment of malonic acid half-esters with formaldehyde in pyridine containing piperidine. Yields are ca. 80%. A somewhat less efficient scheme utilizes a reaction between silyl keten acetals and chloromethyl methyl ether followed by pyrolytic removal of methanol (160 °C, KHS04). Esters (121) can also be obtained in 31—83% yield by alkylation of the Diels-Alder adduct of dimethylfulvene and methyl acrylate followed by a retro-Diels-Alder reaction. " ... 

Conversion of Uncomycin 2-acyl esters to corresponding 3,4,7-tris-O-trimethylsilyI ethers. A 1% soln. of the ester in pyridine containing 20% hexamethyldisilazane and 20% trimethylchlorosilane used to give the silyl ethers. After 5 min reaction period, injected I ml into chromatograph Apparatus... 

This new pyridine-containing directing group indeed demonstrated superior selectivity for mono- versus diarylation of 74, and the use of CuF as a scavenger of the generated iodide further improved the yield of 75. Importantly, the same phenylalanine methyl ester 73 could be obtained without any observable epimerization after a mild N-nitrosylation/hydrolysis sequence. 

Detoxifica.tlon. Detoxification systems in the human body often involve reactions that utilize sulfur-containing compounds. For example, reactions in which sulfate esters of potentially toxic compounds are formed, rendering these less toxic or nontoxic, are common as are acetylation reactions involving acetyl—SCoA (45). Another important compound is. Vadenosylmethionine [29908-03-0] (SAM), the active form of methionine. SAM acts as a methylating agent, eg, in detoxification reactions such as the methylation of pyridine derivatives, and in the formation of choline (qv), creatine [60-27-5] carnitine [461-06-3] and epinephrine [329-65-7] (50). 

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. 

CP can also be prepared by the reaction of cellulose with phosphoms oxychloride in pyridine (37) or ether in the presence of sodium hydroxide (38). For the most part these methods yield insoluble, cross-linked, CP with a low DS. A newer method based on reaction of cellulose with molten urea—H PO is claimed to give water soluble CP (39). The action of H PO and P2 5 cellulose in an alcohol diluent gives a stable, water-soluble CP with a high DS (>5% P) (40). These esters are dame resistant and have viscosities up to 6000 mPa-s(=cP) in 5 wt % solution. Cellulose dissolved in mixtures of DMF—N2O4 can be treated with PCl to give cellulose phosphite [37264-91-8] (41) containing 11.5% P and only 0.8% Cl. Cellulose phosphinate [67357-37-5] and cellulose phosphonate [37264-91 -8] h.a.ve been prepared (42). 

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