6-Chloropyridine-3-carboxylate

Better results were obtained by the microbial reduction of 6-chloropyridine 3-carboxylate using carbon monoxide. The product/by-product ratio was about 80, if a carbon monoxide pressure of 20 bar was applied. In another experiment ethylene glycol diethyl ether was used as a second phase in order to transfer the product to the organic solvent (Table 20) (86). 

A solution of 30 ml 0.1 M potassium phosphate buffer, pH 5.6, containing 270 mM 6-chloropyridine-3-carboxylate and 8 g wet packed cells of C. thermoaceticum was stirred under an atmosphere of about 1.1 bar CO. In another experiment 30 ml ethylene glycol diethyl ether was used as the second phase. Before the reaction was started, carbon monoxide was flushed through the solution. For the experiment with 20 bar carbon monoxide a glass flask with a magnetic stirrer containing the above indicated ingredients was put in an 200 ml autoclave. 

Electromicrobial and microbial reduction of 6-chloropyridine-3-carboxylate. The productivity numbers (PN) are given after 7 and 24 h for the uptake of 4 electrons. The organic phase was 30 ml ethylene glycol diethyl ether. 

The degradation of 4-chlorobiphenyl by Sphingomonas paucimobilis strain BPSl-3 formed the intermediates 4-chlorobenzoate and 4-chlorocatechol. Fission products from the catechol reacted with NH4+ to produce chloropyridine carboxylates (Davison et al. 1996) (Figure 2.2c). 

The effect of a carboxy group is illustrated by the reactivity of 2-bromopyridine-3- and 6-carboxylic acids (resonance and inductive activation, respectively) (cf. 166) to aqueous acid under conditions which do not give hydroxy-debromination of 2-bromopyridine and also by the hydroxy-dechlorination of 3-chloropyridine-4-car-boxylic acid. The intervention of intermolecular bifunctional autocatalysis by the carboxy group (cf. 237) is quite possible. In the amino-dechlorination (80°, 4 hr, petroleum ether) of 5-carbethoxy-4-chloropyrimidine there is opportunity for built-in solvation (167) in addition to electronic activation. This effect of the carboxylate ion, ester, and acid and its variation with charge on the nucleophile are discussed in Sections I,D,2,a, I,D,2,b, and II,B, 1. A 5-amidino group activates 2-methylsulfonylpyridine toward methanolic am-... 

Soil Hydrolyzes in soil to 6-chloropyridine-2-carboxylic acid which is readily absorbed by... 

Chloropropionanilide, see Propanil 4 -Chloropropionanilide, see Prottanil 6-Chloropyridine-2-carboxylic acid, see Nitrapyrin Chloroquinone, see Chlorobenzene... 

Cephapirin Cephapirin, (6/ -franx)-3-[(acetyloxy)methyl]-8-oxo-7-[[(4-pyridinylthio) acetyl]amino]-5-thia-l-azabicyclo[4.2.0]oct-2-en-2-carboxylic acid (32.1.2.4), is synthesized by acylating 7-aminocephalosporanic acid with 4-pyridylthioacetic acid chloride (32.1.2.3), which is synthesized by reacting 4-chloropyridine with mercaptoacetic acid in the presence of a base, forming 4-pyridylthioacetic acid (32.1.22), and further transforming the resulting acid to the acid chloride by reacting it with phosphorous pentachloride. 

Diehloro-isonicotinyl Azide. See 2,6 Di-chloropyridine-4-carboxylic Acid Azide in this vol... 

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. 

All four isomeric selenolopyridines which can be derived from benzoselenophene (423— 426 Scheme 123) have been described. Ethyl 3-hydroxyselenolo[2,3-fe]pyridine-2-carboxy-late (429) has been prepared as shown in Scheme 124 (73BSF704). Treatment of ethyl 2-chloropyridine-3-carboxylate with methaneselenol yields (427). Nucleophilic displacement of bromine in bromoacetic acid with subsequent loss of methyl bromide yields (428), which after esterification is cyclized under Dieckmann conditions to give (429). The parent compound (423 colorless oil with b.p. 92 °C/1 mmHg) is prepared either by cyclization of compound (430) and subsequent decarboxylation of the intermediate acid (equation 57) or by reduction of 2-nitroselenophene and subsequent condensation of the amino compound with malonaldehyde bis(diethyl acetal) in the presence of zinc chloride (equation 58) (76BSF883). Selenolo[3,2-6]pyridine (426 b.p. 127-129°C/10 mmHg m.p. 35.5-37.0°C) has been obtained in an analogous manner. 

Reaction of 3,5-dimethyl-4-methoxy-2-chloropyridine 1 with 5-methoxy-2-(methylcarboxylate)-thiobenzimidazole 2 followed by treatment with ammonia to give the carboxylate thioether 3. Compound 3 was oxidized to give the carboxylate sulfoxide 4 which is decarboxylated to give omeprazole 5. 

Chloropyridine-3-carboxylic acid reacts with either the anion of acetylacetone or ethyl aceto-... 

Yet disconnection (a), on the face of it, seems to pose an even greater problem because we now have to construct an amine in the presence of an acyl chloride However, we shall want to make the acyl chloride from the carboxylic acid, which can then easily be disconnected to 2-aminobenzoic acid (anthranilic acid) and 4-chloropyridine,... 

Pyridones are easy to prepare (see Chapter 44) and can be alkylated on oxygen as predicted by their structure. A more important reaction is the direct conversion to chloropyridines with POCI3. The reaction starts by attack of the oxygen atom at phosphorus to create a leaving group, followed by aromatic nucleophilic substitution. The overall effect is very similar to acyl chloride formation from a carboxylic acid. 

Synthesis of flavocarpine was achieved by use of a modification of the method worked out by Ban and Seo (186i), in which a 2-chloropyridine is condensed with 3-(2-bromoethyl)-indole to form th e required ring system directly. Thus, to provide the eventual carboxyl group of flavocarpine, a cyano group was introduced into 3-ethylpyridine. This was... 

Pyridine V-oxides may be deprotonated to give ylides which react with electrophiles such as carbon dioxide and ketones. For example, 4-chloropyridine /V-oxide reacts with butyllithium at -65 °C followed by quenching with carbon dioxide to give 4-chloropyridine A -oxide 2-carboxylic acid in 49% yield. Quinuclidine yV-oxide can be deprotonated with r-butyllithium to give the anion which can be trai ied with deuterium oxide or benzaldehyde. ... 

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