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Abstract(s)
O presente trabalho experimental teve como objetivo principal a síntese de novos pseudo-C-nucleósidos por construção de anéis heterocíclicos, nomeadamente o isoxazol e o pirazol, a partir de derivados glucídicos. Os compostos obtidos são produtos com possível atividade biológica. Nas sínteses efetuadas foram usadas técnicas gerais de síntese com o objetivo de tentar obter os compostos de modo económico e simples.
Foram utilizados como compostos de partida a D-Galactopiranose e o 1,2:5,6-Di-O-isopropilideno-α-D-glucofuranose, que através de diversas reações originaram os anéis isoxazol e pirazol em derivados de hidratos de carbono.
Foram realizadas reações de proteção dos grupos hidroxilo, reações de oxidação, clivagem oxidativa e reações de aumento da cadeia carbonada.
Os pseudo-C-nucleósidos com o anel heterocíclico isoxazol foram obtidos por reação de condensação aldólica.
A síntese dos pseudo-C-nucleósidos com o anel heterocíclico pirazol foi obtida por reação de aumento de cadeia carbonada, aplicando as condições da reação de Wittig, seguido de ciclização com hidrazina.
O controlo das reações foi realizado pela técnica de cromatografia em camada fina e, sempre que necessário, o isolamento e purificação dos compostos sintetizados foi efetuada pela técnica de cromatografia em coluna a pressão moderada.
A caracterização dos compostos sintetizados foi efetuada pela análise dos espectros de ressonância magnética nuclear de protão e de carbono.
The aim of this experimental work was the synthesis of new pseudo-C-nucleosides through the formation of heterocyclic rings, namely the isoxazole and pyrazole derivatives from carbohydrates. The obtained compounds are products with possible biological activity. The performed syntheses were made using general synthesis techniques in order to produce the compounds in an inexpensive and simple manner. D-galactopyranose and 1,2:5,6-Di -O- isopropylidene-α-D-glucofuranose were used as starting compounds which, through various reactions, generated the ring isoxazole and pyrazole in derivatives of carbohydrates. Reactions were performed for the protection of hydroxyl groups, oxidation reactions, oxidative cleavage and reactions for increasing the carbon chain. Pseudo-C-nucleosides with the heterocyclic ring isoxazole were obtained by aldol condensation reaction. The synthesis of the pseudo-C-nucleosides with the heterocyclic ring pyrazol was obtained by the reaction of increasing the carbon chain, applying the Wittig reaction conditions, followed by cyclization with hydrazine. The control of the reactions was determined by thin layer chromatography technique and the isolation and purification of the synthesized compounds was performed using the column chromatography technique at moderate pressure. The characterization of the synthesized compounds was performed by spectrodcopic analysis of the nuclear magnetic resonance of proton and carbon thirteen.
The aim of this experimental work was the synthesis of new pseudo-C-nucleosides through the formation of heterocyclic rings, namely the isoxazole and pyrazole derivatives from carbohydrates. The obtained compounds are products with possible biological activity. The performed syntheses were made using general synthesis techniques in order to produce the compounds in an inexpensive and simple manner. D-galactopyranose and 1,2:5,6-Di -O- isopropylidene-α-D-glucofuranose were used as starting compounds which, through various reactions, generated the ring isoxazole and pyrazole in derivatives of carbohydrates. Reactions were performed for the protection of hydroxyl groups, oxidation reactions, oxidative cleavage and reactions for increasing the carbon chain. Pseudo-C-nucleosides with the heterocyclic ring isoxazole were obtained by aldol condensation reaction. The synthesis of the pseudo-C-nucleosides with the heterocyclic ring pyrazol was obtained by the reaction of increasing the carbon chain, applying the Wittig reaction conditions, followed by cyclization with hydrazine. The control of the reactions was determined by thin layer chromatography technique and the isolation and purification of the synthesized compounds was performed using the column chromatography technique at moderate pressure. The characterization of the synthesized compounds was performed by spectrodcopic analysis of the nuclear magnetic resonance of proton and carbon thirteen.
Description
Keywords
Anéis heterocíclicos Isoxazol Derivados glucídios Reacção de wittig