Studies on Pyrido [2, 3-d] pyrimidine 3-Oxide

Abstract

The reaction of pyrido [2, 3-d] pyrimidine (I) with several nucleophilic reagent was carried out. In the reaction of I with hydrazine reagent added across the 3, 4-positions in I to result in the formation of 3-hydroxy-4-hydrazino-3, 4-dihydropyrido [2, 3-d] pyrimidine (V). In the case of the reaction with acetic anhydride ring fission between the 2- and 3-positions took place and resulted in the formation of 2-aminonicotinonitrile (VI). The similar ring fission also occurred in the use merely alkali hydroxide for I at ordinary temperature to form 2-(formylamino) nicotinoaldehyde oxime (VII). In the case of the reactions with ethyl cyanoacetate, malononitrile and ethyl acetoacetate without base catalyst the transformation of I into 1, 8-naphthyridine derivatives proceeded to result in the formation of ethyl 2-amino-1, 8-naphthyridine-3-carboxylate (X), 2-amino-1, 8-naphthyridine-3-carbonitrile (XI) and ethyl 2-methyl-1, 8-naphthyridine-3-carboxylate (XII), respectively. In the case of the reaction with symmetric β-diketone without base catalyst 2-substituted-pyrido [2, 3-d] pyrimidine was formed. Thus the reactions with 2, 4-pentanedione and with 1, 3-diphenyl-1, 3-propanedione gave 1-(2-pyrido [2, 3-d] pyrimidinyl)-2-propanone (XX) and 2-(2-pyrido [2, 3-d] pyrimidinyl) acetophenone (XXI), respectively. But in the case of the reaction with asymmetric β-diketone such as 1-phenyl-1, 3-butanedione it proceeded in a defferent way from the reaction with symmetric β-diketone and resulted in the transformation of I into 2-phenyl-1, 8-naphthyridine (XXVIII). The possible reaction processes for the reactions described above were also proposed and discussed.