Reduction of 5-Nitrosalicylic Acid in Water to Give 5-Amino-salicylic Acid*

Abstract

In the course of a general programme aimed to find new protocols for environmentally friend chemistry [1-3] we were looking for a clean, high yielding method of reduction of 5-nitrosalicylic acid (1) to 5-aminosalicylic acid (5-ASA) in industrial scale [4].[...]

C–H nitrogenation and oxygenation by ruthenium catalysis

“…Indeed, ethyl 2-hydroxy-5-nitrobenzoate could be easily converted to Mesalazine by sequential hydrolysis and reduction. 35 Studies on ruthenium-catalyzed C(sp 2 )-H bond oxygenation of arenes 11 bearing amide directing groups identified the userfriendly, inexpensive [RuCl 3 ÁnH 2 O] as a viable catalyst. PhI(OAc) 2 proved to be an efficient oxidant, while O 2 , Cu(OAc) 2 ÁH 2 O, t-BuOOH, oxone, K 2 S 2 O 8 or PhI(TFA) 2 were found to be inferior.…”

“…The past two years have witnessed a tremendous development in the direct hydroxylation of C(sp 2 )-H bonds in arenes and heteroarenes with readily accessible ruthenium catalysts (Scheme 14). [33][34][35][36][37][38][39][40][41][42] While Rao and coworkers used the complex [RuCl 2 (p-cymene)] 2 as the precatalyst and K 2 S 2 O 8 or HIO 3 as the oxidant, 34 our group employed [RuCl 2 (p-cymene)] 2 , as well as the well-defined ruthenium(II) biscarboxylate complex [Ru(O 2 CMes) 2 (p-cymene)] ( 24), 33 or inexpensive [RuCl 3 ÁnH 2 O] and (diacetoxyiodo)benzene [PhI(OAc) 2 ] as the oxidant. For chelation-assisted C-O bond formation on arenes the solvent mixture comprising of TFA and TFAA turned out to be critical, which enabled successful hydroxylation of electron-deficient and electron-rich arenes as well as heteroarenes [33][34][35][36][37][38][39][40][41][42] with weakly coordinating directing groups, 23 such as esters or ketones.…”

“…[33][34][35][36][37][38][39][40][41][42] While Rao and coworkers used the complex [RuCl 2 (p-cymene)] 2 as the precatalyst and K 2 S 2 O 8 or HIO 3 as the oxidant, 34 our group employed [RuCl 2 (p-cymene)] 2 , as well as the well-defined ruthenium(II) biscarboxylate complex [Ru(O 2 CMes) 2 (p-cymene)] ( 24), 33 or inexpensive [RuCl 3 ÁnH 2 O] and (diacetoxyiodo)benzene [PhI(OAc) 2 ] as the oxidant. For chelation-assisted C-O bond formation on arenes the solvent mixture comprising of TFA and TFAA turned out to be critical, which enabled successful hydroxylation of electron-deficient and electron-rich arenes as well as heteroarenes [33][34][35][36][37][38][39][40][41][42] with weakly coordinating directing groups, 23 such as esters or ketones. 33-42 Thus, the ruthenium-catalyzed ortho-hydroxylation of benzoates 25 was found to be generally useful for the preparation of highly functionalized arenes, some of which are difficult to access via conventional approaches (Scheme 15).…”

Solubility of 5-Nitro- and 3-Nitrosalicylic Acids in an Acetic Acid/Nitric Acid Mixture

“…5-Nitrosalicylic acid is the basic intermediate in the synthesis of mesalazine starting from salicylic acid . Mesalazine is one of the most important active species used in the pharmaceutical field for the treatment of various pathologies such as ulcerative colitis and Crohn's disease. , In a recent study, a novel method was proposed to obtain 5-nitrosalicylic acid using the system HNO 3 /CH 3 COOH for the nitration of salicylic acid.…”