Reação de difenilciclopropenona com 2-aminopiridinas e compostos relacionados

AUTOR(ES)
DATA DE PUBLICAÇÃO

1975

RESUMO

Diphenylcyclopropenone reacts with 2-aminopyridines in diethyl ether to give cis-3,4-dihidro-3,4-diphenyl-2H-pyrido [1,2-a] pyrimidin-2-ones and N(2-pyridil) cis-2,3-diphenylacrylamides. The same reaction in methanol leads to trans-pyridopyrimidin-2-ones and crylamides. In methanol the cis-pyridopyrimidin-2-ones isomerize to trans-pyridopyrimidin-2-ones and acrylamides. The identification of the pyridopyrimidin-2-ones was achieved by comparison of their spectral data with those of known compounds and, in the case of the trans isomers, by catalytic hydrogenation. The acrylamides were hidrolyzed in KOH/EtOH to produce aminopyridines and cis-2,3-diphenylacrylic acid. The mecanism of formation of these compounds was studied and it became evident that the nucleophilic center was the ring nitrogen of the 2-aminopyridine, which is suggested to react through a conjugate addition to diphenylcyclopropenone. When the 2-aminopyridine has electron attracting substituents such as clorine and bromide, the reactivity decreases and the reaction proceeds only under reflux giving the corresponding acrylamides. The reaction of diphenylcyclopropenone with 2-aminopyrimidines occurs under reflux yielding 1:1 and 2:1 addition compounds. These were hidrolyzed by heating under reflux with concentrated hydrochloric acid yielding acrylamides and cis-2,3-diphenylacrilic acid. Diphenylcyclopropenone also reacts with 3-amino-1,2,4-triazines,, forming 1:1 cyclic compounds (aminopirrolotriazines). The reaction of diphenylcyclopropenone with aminopyrazine resulted in a 2:1 addition compound. For all reactions, possible mechanismes are discussed.

ASSUNTO(S)

reações quimicas cinetica quimica polimerização

ACESSO AO ARTIGO

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