FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Sete novos precursores de a-aminoÃcidos foram preparados atravÃs da reaÃÃo de alquilaÃÃo do acetoamidocianoacetato de etila 112 utilizando bromo-hexano, cloreto de benzila, brometo de alila, 9-(clorometil)-antraceno, brometo de 3-nitrobenzila, brometo de 4-nitrobenzila, brometo de 4- metoxibenzila e brometo de 2-metilnaftaleno como agentes alquilantes via CatÃlise de TransferÃncia de Fase (CTF). Tais reaÃÃes foram realizadas a 70oC, utilizando cloreto de benziltributilamÃnio como catalisador. ApÃs 5h de reaÃÃo, foram obtidos os compostos 113a-h com rendimentos que variaram de moderados a bons (24-74%), (Esquema I). A reaÃÃo de alquilaÃÃo do acetoamidocianoacetato de etila 112 com cloreto de benzila foi realizada utilizando os seguintes catalisadores quirais: Brometo de N-benzilmetilefedrÃnio (31a), Cloreto de (8R,9S)-N-9-metilantracenilcinchonidÃnio (34b), Cloreto de (8S,9R)-N-9-metilantracenilquinÃnio (34a), Cloreto de (8R,9S)-N-benzilmetilcinchonidÃnio (32b), Brometo de N-(benzilmetil)-O-alil-efedrÃnio (31g), Cloreto de (8S,9R)-NbenzilmetilcinchonÃnio (33b), Brometo de N-(9-metilantracenil)-O-alilcinchonidÃnio (34e) e Cloreto de (8S,9R)-N-9-metilantracenilcinchonÃnio (34d).
NÃo foi observada induÃÃo assimÃtrica para as reaÃÃes utilizando os catalisadores supracitados na produÃÃo do precursor de a-aminoÃcido 113b. Ainda que nÃo tenha ocorrido induÃÃo assimÃtrica, bons rendimentos (83%) foram obtidos com os catalisadores 34e e 34d. Com base nos resultados obtidos a partir do programa de modelagem molecular Gaussian 03 foi possÃvel propor um modelo de aproximaÃÃo enolato-catalisador que justifica a falta de induÃÃo assimÃtrica observada com a utilizaÃÃo dos catalisadores quirais testados.a-aminoÃcidos 114 foram obtidos a partir dos precursores 113 atravÃs de hidrÃlise Ãcida, em rendimentos que variaram de moderados a bons (68-93%), (Esquema II). / Seven novel a-aminoacids precursors were prepared by the
alkylation reaction of ethyl acetamidocyanoacetate 112 using bromohexane, benzyl chloride, allyl bromide, 9-(chloro-methyl)antracene, 3-nitrobenzyl bromide, 4-nitrobenzyl bromide, 4-metoxibenzyl bromide and 2-methyl-naphtyl bromide as alkylating agents via Phase Transfer Catalysis (PTC). These reaction were performed at 70oC using benzyltributyl ammonium chloride as catalyst. After 5h, compounds 113a-h were obtained in moderated to good yields (24-74%), Scheme I. The alkylation reaction of ethyl acetamidocyanoacetate 112 with benzyl chloride was carried out using chiral catalysts phase transfer as: Nbenzylmethylephedrinium bromide (31a), (8R,9S)-N-9-methylantracenylcinchonidinium chloride (34b), (8S,9R)-N-9-methylantracenylquininium chloride (34a), (8R,9S)-Nbenzylmethylcinchonidinium chloride (32b), N-(benzilmethyl)-O-allylephedrinium bromide (31g), (8S,9R)-N-benzylmethylcinchoninium chloride (33b), N-(9-methylantracenyl)-O-allyl-cinchonidinium bromide (34e) and (8R,9S)-N-9-methylantracenylcinchoninium chloride (34d). No asymmetric induction was observed using the aforementioned catalysts for the production of a-aminoacid optically active precursor 113b. Although no asymmetric induction was observed, good yields (83%) were obtained with catalysts 34e and 34d.Based on the data obtained from molecular modeling program Gaussian 03, it was possible to propose a model for the enolate-catalyst pair, that is in accordance with the lack of asymmetric induction for the reactions performed in the presence of the chiral catalysts. a-aminoacids 114 were obtained from precursors 113 by acid hydrolysis with moderate to good yields (68-93%), (Scheme II).
| Identifer | oai:union.ndltd.org:IBICT/oai:www.teses.ufc.br:3550 |
| Date | 16 February 2009 |
| Creators | Rosa VirgÃnia Soares Mamede |
| Contributors | Marcos Carlos de Mattos, Mary Anne Sousa Lima, Gilvandete Maria Pinheiro Santiago |
| Publisher | Universidade Federal do CearÃ, Programa de PÃs-GraduaÃÃo em QuÃmica, UFC, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFC, instname:Universidade Federal do Ceará, instacron:UFC |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0021 seconds