Interceptação nucleofilica do intermediario 5-(2-furoil)-2-penteno-4-inal a partir da monotosilhidrazona de furila : sintese de sistemas ciclicos e heterociclicos a partir de animais e hidrazinas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

In this work we developed a new "on step" metlhod for the synthesis of furil from furfural, which employs thiamine (vitamin B-1) as the catalys. This method proved to be very promissing in that, preliminary studies indicate that several other diazoketones 2,2 -pyridil [55], 2.2 -thenil [56] and benzyl [57] can be obtained efficiently by the same approach. Also it avoids the use of sodium cyanide, and shows much higher yields when compared to the conventional methods. The main part of this work involves a reactivity study of furil monotosythydrazone [49], which in basic medium yields "in situ" the diazoketone [50] . Reactions of [49] with several amines, hydrazine hydrate and its derivatives led to the formation of several cyclic and nitrogenated heterocyclic systems. In reactions with amines and hydrazine hydrate 5-(2-furoymethylene)-2-pyrrolidinones [53] and [62) were obtained. In reactions with methyihidrazine 1-methyl-6-(2-furoilmethylene)-pyridazinyl [64) was formed while phenyl and p-nitrophenyl hidrazines yielded 1-(2-furocyl)-6-aniline- 6-aza-fulven [65) and 1-(2-furoyl)-6-(4-p-nitro)- aniline-6-aza-fulven [67], respectively. Such products [53], [62), [65) e [67] are formed by the interception the g,d-acetylenic a,b-olefinic aldehyde [52] intermediate, which is formed by the spontaneous decomposition of the diazoketone [50]. Although nucleophiles with diferent strengths were used, ketocarbene [51], which is a possible intermedia between [50] e [52], was not intercepted.

ASSUNTO(S)

hidrazina quimica organica - sintse catalisadores reação nucleofilica

ACESSO AO ARTIGO

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