Thiazole-4,5-dicarboxylic acid, from

Thiazole carboxylic acid (70), R, - Rj = H, can be also obtained from decarboxylation of 2,5-thiazole dicarboxylic acids. 

There are two series of benzisothiazoles, derived from benz[c]iso-thiazole (2) and benz[d]isothiazole (3), and both, if the benzene ring were suitable weakened, could doubtless be oxidized to isothiazole-dicarboxylic acids. In their first synthesis Adams and Slack... 

Azole approach. Like phthalazinones, which can be formed from the reaction between phthalic acids and hydrazines, the thiazole analogues can be formed from thiazole-4,5-dicarboxylic acid derivatives. Other 4,5-substituted oxo groups react similarly to give a fused thiazole (451) (71BSF1491). 

Thiazole-4,5-dicarboxylic acid ethyl esters, from diethyl a-chloro d-keto-succinate and thioamides, 206... 

Thiazolylthiourea, from dithiobiuret and aromatic o-haloketones, 244 (a-Thienyl)-thiazole-4,5-dicarboxylic acid, pyrolysis of, 206... 

Figure U.1D. Nicotinamide analogs tested in pellagra or animal models of pellagra. The active compounds include (1,2, 6, 11, 12, 13,15,18, and 20). Compounds active in some models or in pellagrainclude (7,17,21), pyrazine-2,3-dicarboxylic acid, NAD, pyridyl-3-aldehyde,pyridyl-3-carbi-nol, tryptophan, and 3-hydroxyanthranilicacid. The inactive compounds are (3,4,5,8,9,10,14,16, 19), 3-arninopyridine,thiazole-5-carboxylicacid, 2-methylpyridine, 3-methylpyridine, 2,6-dimethyl-pyridine-3,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, kynurenine, 3-hydroxykynurenine, and formylkynurenine. This figure is from Ref 33 and is used with permission.

Hattori T, Kagawa K, Kakimoto M and Imai Y (1993) Novel 2-step synthesis of poly(benzo-thiazoles) via new precursor polyamides from 2,5-bis[(cyanoethyl)thio]-l,4-phenylenediamine and aromatic dicarboxylic-acid chlorides. Macromolecules 26 4089-4093. 

Dimethyl-3,5-dimethyl-l//,3//-pyrrolo[l,2-r ][l,3]thiazole-6,7-dicarboxylate 399 (R = H) was prepared from cysteine 396 using the method developed of Padwa et al. <1989JOC644>. The thiazolidine carboxylic acid 397 (R = H), obtained by reaction of the cysteine with formaldehyde, was heated in the presence of acetic anhydride and DMAD to give the sulfide 399 by dipolar cycloaddition of the acetylene to the intermediate dipole 398 (Scheme 59) <2002J(P1)1795>. 

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