2-Pyridinecarboxylic acid esters

In a similar manner, 2,4,6-trisubstituted 3-pyridinecarboxylic acid esters have been prepared using a mixture of a, 3-ketoesters, propargylic alcohols, ammonium acetate and Mn02. The reaction proceeds by oxidation of the propargylic alcohol to the corresponding ketone, which reacts with the enamine being formed from the like loos lor and ammonium acetate. For this domino process, normal heating at 70 °C was used. 

Wisniewski, M. Palladium(II) extraction by pyridinecarboxylic acid esters. J. Radioanal. Nucl. Chem. 2000, 246, 693-696. 

Cote, G., Jakubiak, A., Bauer, D., Szymanowski, J., Mokili, B., and Poitrenaud, C. (1994) Modeling of extraction equilibrium for copper(II) extraction by pyridinecarboxylic acid esters from concentrated chloride solutions at constant water activity and constant total concentration of ionic or molecular species dissolved in the aqueous solution, Solvent Extr. Ion Exch., 12(1), 99-120. 

Reduction of pyridinecarboxylic acid methyl esters with a large excess of sodium borohydride in methanol is reported to give the corresponding alcohol. Thus, using a twentyfold excess of hydride, nicotinic acid gave high yields of 3-hydroxymethylpyridine. Similar reductions of unsaturated pyridinecarboxylic acid esters such as X-124 gave predominantly the saturated alcohols pC-125). 

Chemical Name 3-pyridinecarboxylic acid 2,2-bis[[(3-pyridinylcarbonyl)oxy] methyl]-1,3-propanediyl ester... 

Niacin methyl ester nicometh 3-carbomethoxypyridine methyl 3-pyridinecarboxylate 3-pyridinecarboxylic acid methyl ester... 

CN 3-pyridinecarboxylic acid 2-[2-(4-chlorophenoxy)-2-methyl-l-oxopropoxy]ethyl ester... 

CN ( )-cw-3-pyridinecarboxylic acid 2-oxo-l-phenyl-2-[(3,3,5-trimethylcyclohexyl)oxy]ethyl ester... 

RN 70-19-9 MF Ci.HijNOj MW 207.23 EINECS 200-727-5 CN 3-pyridinecarboxylic acid (tetrahydro-2-furanyl)methyl ester... 

I CN 6-[(3,4-dihydro-4,4-dimethyl-2//-l-benzothiopyran-6-yl)ethynyl]-3-pyridinecarboxylic acid ethyl ester... 

A bicyclic urea (123) was an unexpected product of the reaction between pyrrolidine and the phenyl ester of 2-cyano-l,4,5,6-tetrahydro-l-pyridinecarboxylic acid (124 R = Ph) the corresponding methyl ester (124 R = Me) reacted, as expected, to give the product of Michael addition (125). ° The better leaving ability of phenoxide vs methoxide presumably tilted the reaction towards the substitution rather than the addition product, although thiols (e.g. PhSH) underwent only the addition reaction. 

Pyridinecarboxylic acids exist largely in the zwitterion form in water (57JA2050). They can be converted into esters with alcohols and mineral acid catalysis, and by use of diazoalkanes. Use of alkyl halides in alkali gives N-alkylbetaines. Esters can also be formed from acid chlorides but the latter are liable to self-quaternization. 

Chemical Name 3-Pyridinecarboxylic acid 3,3,5-trimethylcyclohexyl ester... 

Ethoxycarbonylmethyl-3-pyridinecarboxylic acid (99) with a Vilsmeier reagent (made in situ) gave 6-methyl-5-oxo-5,6-dihydro-1,6-naphthyridine-8-carboxylic acid (100) (substrate, Me2NCHO, POCI3, 0°C, 1 h, then 95°C, 6 h 69% note the hydrolysis of the ester grouping).876... 

Oxidation of pyridinecarboxylic acids.1 Reaction of a pyridinecarboxylic acid or the ester with 10% F2 in N2 results in oxidation to the corresponding 2-pyridone in 50-75% yield. An N-fluoropyridinium salt is probably an intermediate. 

CN 3-pyridinecarboxylic acid 3-[2-f4-chlorophenoxy)-2-methyl-1 -oxopropoxy]propyl ester hydrochloride... 

The 4-pyridinecarboxylic acids [440, 441], 2-carboxythiazoles [445] and 2-carboxyi-midazoles [436, 446], and their esters amides, and thiamides [392, 447-450] are reduced in this way. The corresponding hydrazides [451] and hydroxamic acids [51] are reduced to the amides in the first step and then further reduced. When the activating group in pyridine is in the 3-position the reduction may take place in the nucleus, depending on pH. 

---