Collect. Czech. Chem. Commun. 1984, 49, 2628-2634

Synthesis of 1,2,4-triazino[5,6-b]- and imidazo[4,5-b]quinoline derivatives

Jan Sloukaa, Vojtěch Bekáreka, Karel Nálepaa and Antonín Lyčkab

a Department of Analytical and Organic Chemistry, Palacký University, 771 46 Olomouc
b Research Institute of Organic Syntheses, 532 18 Pardubice-Rybitví


o-Nitrophenylpyruvic acid thiosemicarbazone (I) has been cyclized to 2-thio-5-(o-nitrobenzyl)-6-azauracil (II) which has been transformed in 5-(o-nitrobenzyl)-6-azauracil (III) by both oxidation, and methylation and hydrolysis of the 3-methylmercapto-6-(o-nitrobenzyl)-2,5-dihydro-1,2,4-triazin-5-one (V) formed. Reduction of derivative III with iron(II) hydroxide and cyclization of the amino derivative IV formed gives 2,3,4,10-tetrahydro-1,2,4-triazino[5,6-b]quinolin-3-one (VI). Compound VI is transformed in acid medium to 1-amino-1,2-dihydroimidazo[4,5-b]quinolin-2-one (VIII) via the tautomer VII, and in boiling acetic acid it gives the acetylamino derivative IX. The N-amino derivative VIII reacts with carbonyl compounds to give the corresponding hydrazones X - XII, and its nitrosation gives 1,2-dihydroimidazo[4,5-b]quinolin-2-one (XIII).