Derivatives of 4-Amino- and 4-Ureido-2-phenyl-1,2,3-triazole-5-carboxylic Acid 1-Oxides

Abstract

4-Amino-and 4-ureido-1,2,3-triazole-5-carboxylic acid oxides, as well as their hydrazides and methylamide, were prepred via pyrimidine ring opening in isomeric 2-phenyl[1.2.3]triazolo [4,5-d]pyrimidine-5,7-dione N-oxides. Recyclization of the pyrimidine ring in azolopyrimidines under the action of nucleophiles provides a convenient synthetic approach to heteroaromatic amino acids and their derivatives. This approach has been used to prepare coffeidine [1], previously hardly available 3-amino-and 3-ureido-1,2,5-triazole-5-carboxylic acids and their amides, anilides, and hydrazides [234], as well as amino acids of the oxaand selenadiazole series [5].The aim of the present work was to extend the above approach to derivatives of 1,2,3-triazole ÄÄÄÄÄÄÄÄÄÄÄÄ N-oxides.We found that boiling of 2-phenyl[1.2.3]triazolo-[4,5-d]pyrimidine-5,7-dione 1-oxide (Ia) [6] with aqueous sodium hydroxide and ammonia results in hydrolysis of the pyrimidine ring to form 4-amino-(II) and 4-ureido-2-phenyl-1,2,3-triazole-5-carboxylic acid 1-oxides (III), respectively. Unlike the reaction with aqueous ammonia, the reaction of compound Ia with aqueous methylamine provides N-methyl-2-phenyl-4-ureido-1,2,3-triazole-5-carboxamide 1-oxide (IV). Scheme 1.