Aminophenylpyruvic acid

In 1897, Reissert reported the synthesis of a variety of substituted indoles from o-nitrotoluene derivatives. Condensation of o-nitrotoluene (5) with diethyl oxalate (2) in the presense of sodium ethoxide afforded ethyl o-nitrophenylpyruvate (6). After hydrolysis of the ester, the free acid, o-nitrophenylpyruvic acid (7), was reduced with zinc in acetic acid to the intermediate, o-aminophenylpyruvic acid (8), which underwent cyclization with loss of water under the conditions of reduction to furnish the indole-2-carboxylic acid (9). When the indole-2-carboxylic acid (9) was heated above its melting point, carbon dioxide was evolved with concomitant formation of the indole (10). 

A soln. of methyl p-amino-a-benzamidocinnamate monohydrate in 12 N HGl refluxed 2.5 hrs. p-aminophenylpyruvic acid hydrochloride. Y 86%. Also modified procedure s. A. P. Martinez, Am. Soc. 82, 6050 (1960). 

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See also in sourсe #XX -- [ ]

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