XXVI.—Nitro-, arylazo-, and amino-glyoxalines

Abstract

By ROBERT GEORGE FARGHER and FKANK LEE PYMAN. THIS investigation was begun with the object of effecting the synthesis of purine derivatives by a method complementary to those which have been employed hitherto. In these, the pyrimidine nucleus is first built up and the glyoxaline ring closed subsequently. We proposed to prepare 4-aminoglyoxaline-5-carboxylic' acid,* condense it with cyanic acid, and eliminate water with t,he production of xanthine. Such a synthesis would be of interest in view of the suggestion that purine derivatives originate from histidine in the animal body (compare Hopkins, T., 1916, 109, 629). Although the starting material for the proposed synthesis, 4-aminoglyoxaline-5-carboxylic acid, was unknown, we did not anticipate that its preparation woald offer any serious difficulty. We have, however, so far failed t o obtain this substance, and now give an account of our attempts to prepare this and other aminosubstituted glyoxdines. An account of the investigation may be subdivided under three headings: first, the preparation of the glyoxalines and their carboxylic acids, which were required as starting materials ; second, the preparation and properties of nitroglyoxalines; and last, the preparation and properties of arylazoglyoxalines. * In glyoxalines containing a free imino-group, the 4-and 5-positions are equivalent.

Reactivity studies of (η6-arene)ruthenium(II) dimers with arylazoimidazole ligands: molecular structure of [(η6-p-cymene)RuCl(Me-C6H4-Nequals;N-C3H2N2-1-CH3)]PF6

“…1-Methyl-2-(arylazo)imidazole (aai-Me), 1-ethyl-2-(arylazo)imidazole (aai-Et) and 2-(arylazo)imidazole (aai-H) were synthesized by coupling the aryldia-zonium ions with imidazole in aqueous sodium carbonate solution (pH ¼ 7) and purified by the reported method [27]. The alkylation was carried out by adding alkyl halide in dry THF solution to the corresponding 2-(arylazo) imidazole in the presence of sodium hydride [34].…”

Syntheses and characterization of η5-cyclopentadienyl and η5-indenyl ruthenium(II) complexes of arylazoimidazoles: The molecular structure of the complex [(η5-C5H5)Ru(PPh3)(C6H5–N N–C3H3N2)]+

“…1-Methyl-2-(arylazo)imidazole (aai-Me), 1-ethyl-2-(arylazo)imidazole (aai-Et) and 2-(arylazo)imidazole (aaiH) were synthesized by coupling the aryldiazonium ions with imidazole in aqueous sodium carbonate solution (pH 7) and purified by the reported method [22]. The alkylation was carried out by adding alkyl halide in dry THF solution to the corresponding 2-(arylazo) imidazole in the presence of sodium hydride [29].…”

N-(Aminoiminomethyl)-carbamic Acid, 1,1-Dimethylethyl Ester (Boc-guanidine)

“…10, 11 The first, though indirect, synthesis of 2-aminoimidazoles was achieved by diazonium coupling of an arylazo derivative with glyoxal and subsequent reduction to the 2-aminoimidazoles. 12 Production of 2-aminoimidazoles based on the conversion of α-haloketones with guanidine was first carried out with guanidine hydrochloride and in situ deprotonation, as well as with salt-free guanidine, but all these reactions provided significant amounts of by-products. Only the replacement of guanidine by acetyl-guanidine, as shown by Webber and coworkers, provided the desired 2-N-acetyl-substituted 2aminoimidazoles in good yields.…”