2-Mercaptonicotinic acid

Nishiyama and Kuninori [65] described a combination method of assay for penicillamine using HPLC and postcolumn reaction with 6,6 -dithiodi(nicotinic acid). Thiols were separated by HPLC on a reversed-phase column (25 cm x 4.6 mm) packed with Fine Sil 08-10, with 33 mM KH2PO4 (adjusted to pH 2.2 with H3PO4) or 33 mM sodium phosphate (pH 6.8) as the mobile phase. Detection was by postcolumn derivatization with 6,6 -dithiodi(nicotinic acid), and measurement of the absorbance of the released 6-mercaptonicotinic acid was made at 344 nm. The detection limit for penicillamine was 0.1 nmol. A comparison was made with a... 

Mercaptonicotinic acids 173 were used in the syntheses of imines 174 by reaction with carbodiimides (81MI1) (Scheme 60). 

A fused thietone, the pyridothietone (54), was produced as the major product by flash vacuum pyrolysis of 2-mercaptonicotinic acid at 550 °C and ca. lxlO-2 torr, together with a trimer <02TL5285>. 

A detailed account of condensation reactions used in heterocyclic chemistry can be found in Section 8.2.6, in Chapter 10 [97], and, for cycloaddition reactions, in Chapter 11 [98]. A previously unknown class of compounds, spiro[3H-indole-3,2 -[41-f] pyrido[3,2-e]-l,3-thiazine]-2,4 (ll-f) diones, can be synthesized by reaction of in situ-generated 3-indolylimine with 2-mercaptonicotinic acid under the action of MW in the absence of solvent. Both neat reactions and reactions on solid supports such as silica gel, alumina etc., effectively promote the reaction whereas reactions under thermal heating conditions failed to proceed (Scheme 8.31) [99]. 

Previously unknown pyridothiazines have been prepared by treatment of in situ generated 3-indolylimine derivatives with 2-mercaptonicotinic acid under irradiation conditions, according to Scheme 10.112 [221]. 

Also chitosan-6-mercaptonicotinic acid was used to encapsulate insulin into nanoparticles. After oral administration to rats, glucose tolerance in the body improved fourfold compared to unmodified chitosan nanoparticles. 

Mercaptonicotinic Acid (2-Mercaptopyr-idine-S-carboxylic acid)... 

Route A utilizes the easily available 2-mercaptonicotinic acid as starting material. First, the nicotinic acid is esterified with acidic methanol to afford methyl 2-mercaptonicotinate, which is oxidized chlorine in aqueous acetic acid, followed amination with tert-butylamine, to give methyl 2-t-butylaminosulfonylnicotinate. This, in turn, is subjected to reaction with N,N-dimethylaminodimethylaluminum to afford a nicotinamide, which is finally converted to the target intermediate by de-butylation using tri-fluoroacetic acid. 

SERS data were reported for the N, 0-coordinated 3-aminosalicylic acid, and 5,0-coordinated 2-mercaptonicotinic acid on silver colloids. 

It is known that aryl thiols are more reactive than alkyl thiols due to their lower p a values (5-7) [28]. Aromatic thiols, for example, have already been shown to increase the folding rate of disulfide-cOTitaining proteins more than aUphatic thiols [30, 31]. For a pharmaceutical excipient such as thiolated chitosans, the increased reactivity of the thiol group would further increase its beneficial properties over alkyl thiol chitosan and non-thiolated polymers. Examples of aryl sulfhydryl-bearing compounds covalently attached to chitosan via an amide bond are 6-mercaptonicotinic acid and 4-mercaptobenzoic acid. As mentioned for alkyl thiol chitosan, the amount of free and oxidized thiol groups can be determined by Ellman s method. Examples of developed thiolated chitosans and their degrees of modification are listed in Table 1. 

A rare example of this type is provided by the formation of compound 34 in 30% yield by FVP of 2-mercaptonicotinic acid at 550 °C (Section 3.1 Scheme 6 2002TL5285). 

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