Molecular rearrangement of 1-substituted 3-aminoquinoline-2,4-diones in their reaction with urea and nitrourea synthesis and transformations of reaction intermediates

Abstract

1-Substituted 3-alkyl/aryl-3-amino-1H,3H-quinoline-2,4-diones (6) react with nitrourea to give 3-ureido-1H,3H-quinoline-2,4-diones (10), 9b-hydroxy-3,3a,5,9b-tetrahydro-1H-imidazo[4,5-c]quinoline-2,4-diones (11), and 3,3a-dihydro-5H-imidazo[4,5-c]quinoline-2,4-diones (12). Compounds 11 were dehydrated to 12 by the action of phosphorus pentoxide. All three types of compounds rearrange in boiling acetic acid to give three different types of products of molecular rearrangement. A proposed reaction mechanism is discussed.