5-Nitro-3-aminosalicylic acid

This method has proved particularly useful for the preparation of methyl 6-nitroindoxazene-3-carboxylate,29,27,29, 80,33 an intermediate in the synthesis of p-nitro- and p-aminosalicylic acid (Section II, C,3,c), but 3-acyl27 and 3-methyl28 derivatives have been obtained similarly. In most of the published examples there is a second nitro group meta to the first in the benzene ring. 

Selective reduction of m-dinitrobenzene (121) followed by, successively, diazotiza-tion, introduction of hydroxyl, reduction of the nitro group and carboxylation, yields the antimycobacterial agent p-aminosalicylic acid (122) (Scheme 25) used with the antibiotic streptomycin. A three-step synthesis starting with toluene yields the inexpensive drug thioacetazone (123). 

Anantharaman, R N. Vasudevan, D. Chellammal, S. An improved process for the preparation of 5-aminosalicylic acid by using Titanium/Titania cathode in the electrochemical reduction of 5-nitro-salicylic acid in aqueous ethanolic solutions. Indian IN 184281, 2000 Chem. Abstr. 2004, 141, 277357. 

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