Pyridine corresponding acid

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

Such an easy isomerization of acetylenylbenzoic acid amides implies the formation of a five-membered nonaromatic ring condensed with the pyrazole ring. However, the pyrazole analog of o-iodobenzamide (amide of 4-iodo-l-methylpyrazole-3-carboxylic acid) formed under heating with CuC=CPh in pyridine for 9 h only the disubstituted acetylene in 71 % yield is identical in all respects to the compound obtained from the corresponding acid by successive action of SOCI2 and NH3 (90IZV2089) (Scheme 126). 

Although Hg(02CR)2 (R = m-MeOC6Br4 or o-MeC6Br4) could not be decarboxylated in boiling pyridine and pyridine/nitrobenzene, respectively, the corresponding acids were decarboxylated in molten mercuric trifluoroacetate [Eq. (62)] (75). The products were characterized as the... 

Fluoropyridiniumsulfonates 2 can be synthesized by fluorinating the corresponding pyridine-sulfonic acids or sodium or amine salts with fluorine diluted with nitrogen in acetonitrile, aqueous acetonitrile, or a polyfluoro alcohol.40,41... 

Pyridine and quinoline /V-oxides react with phosphorus oxychloride or sulfuryl chloride to form mixtures of the corresponding a- and y-chloropyridines. The reaction sequence involves first formation of a nucleophilic complex (e.g. 270), then attack of chloride ions on this, followed by rearomatization (see also Section 3.2.3.12.5) involving the loss of the /V-oxide oxygen. Treatment of pyridazine 1-oxides with phosphorus oxychloride also results in an a-chlorination with respect to the /V-oxide groups with simultaneous deoxygenation. If the a-position is blocked substitution occurs at the y-position. Thionyl chloride chlorinates the nucleus of certain pyridine carboxylic acids, e.g. picolinic acid — (271), probably by a similar mechanism. 

The alcohol 177 was converted to starting substrates oxazolidinone 178 by acylation followed by reduction of the azide function along with cyclization. Oxazolidinone 178 was protected with f-butylpyrocarbonate-4-(dimethylamino) pyridine (DMAP) and triethylamine, which was further subjected to reductive cleavage of the benzyl ester unit to afford carboxylic acid 179. The treatment of 179 with solution of l-chloro-/V./V,2-trimethyl-1-propenv I airline resulted in the easy formation of the corresponding acid chloride which on reaction with imine in the presence of triethylamine provided the stereoselective formation of spiro-p-lactam 180. 

In 1983, Barton et al. described a new procedure for the oxidation of saturated hydrocarbons [1] by the use of metallic iron, adamantane, hydrogen sulfide or sodium sulfide, pyridine, acetic acid and a small amount of water. The reactions were run under air and afforded adamant-l-ol together with a mixture of adamant-2-ol and adamantanone. The substrate scope could be extended to other hydrocarbons. However, all of them led to product mixtures of the corresponding alcohol(s) and ketone (Scheme 3.1). 

Oxidation of Pyridines Fe203-catalyzed direct oxidation of pyridine by combined use of molecular oxygen (latm) and isovaleraldehyde in 1,2-dichloroethane gives pyridine N-oxide in 89% isolated yield [145]. Isovaleraldehyde was converted into the corresponding acid under the reaction conditions (Scheme 3.44). 

In most of their reactions, the pyridine- and azinecarboxylic acids and their derivatives behave as any other acid (cf. Scheme 86). However, some acid chlorides can be obtained only as hydrochlorides, and we must also consider decarboxylation. Esterification of pyridine carboxylic acids can be usefully achieved via in situ generation of the acid fluoride. For example, treatment of picolinic acid with a stoichiometric amount of N,N,N,A-tetramethylfluoroformami-dinium hexafluorophosphate (TFFH) in dichloromethane and triethylamine leads to generation of the acid fluoride, which reacts with (3-methyloxetan-3-yl)methanol to give the corresponding ester in 95% yield <2004S2485>. 

Oxo-3, 4-dihydro-2-pyrazinecarboxamide (13) gave 3-chloro-2-pyrazinecar-boxamide (14) (POCl3, pyridine, 40 — 80°C, 4 h 86%) 1119 also corresponding acid.275... 

When the reduction is performed without control of the potential, a mixture of products results. Thus, reduction in sulfuric acid at lead or mercury cathodes of the pyridine carboxylic acids leads to a mixture of picolines andtetra- and hexahydropyridine derivatives.284-287 Derivatives of nicotinic acid are more apt to be reduced in the ring than the 2- and 4-carboxypyridines. Reduction of the corresponding pyridylcarbinoles under identical conditions produces a similar reaction mixture.287... 

Aryl ortho thioesters, which can be readily prepared from the corresponding acid chlorides or methyl esters, react with A-halo compounds, such as 1,3-dibromo-5,5-dimethylhydantoin (DBH) or A-bromosuccinimide, and hydrogen fluoridc/pyridine to give aromatic trifluoromethyl compounds,i.e. formation of... 

Pyridine yields methyl substitution products which bear the same relationship to it that toluene, xylene and mesitylene do to benzene. These homologues like those of bepzene are easily oxidized and yield corresponding carboxyl derivatives or acids, viz., pyridine carboxylic acids, as just discussed. 

Both tert-butyl hypochlorite and N-chlorosuccinimide dehydrogenate primary benzylic alcohols to the aldehydes (equation 213), whereas primary aliphatic alcohols are converted into esters of the corresponding acids [709]. Butyl alcohol dissolved in carbon tetrachloride and treated with tert-butyl hypochlorite in the presence of pyridine at 40-45 C gives, after 2 h, a 66% yield of butyl butyrate [709]. 

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