Estudo da redução de iminas / Stydy of imine reduction

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

This project studies the behavior of a series of imines structurally analogues in bioreductions with baker yeast and carrots, and also with NaBH4 using alternative chiral reagents like 1-amine-2-propanol, prolinol and 2-a- hidroxybenzyl-benzimidazole or tartaric acid. For biocatalysis we investigated different temperatures, solvents and proportions of reagents, but all conditions resulted in hydrolysis of the substrate. The instability of the imines or the lack of affinity can be the cause for these results, even using 18-C-6 as additive and immobilized yeast or substrate. By the chemical imine reduction we tried a simple method of induction, mixing manually NaBH4 and the chiral reagent in a mortar, using different solvents and temperatures, but none of them gave a good enantiomeric excess. Probably there was no coupling between NaBH4 and the chiral reagents, and consequently no preference in for one face in the reduction transition state. MS and NMR analysis have shown the formation of a chiral borohydride, but not an enough amount to give asymmetry in the reduction. A great contribution of this project is the characterization of a chiral borohydride obtained from NaBH4 and S-(+)-2-a-hydroxybenzyl-benzimidazole. It was previously reported, but with no confirmation of its structure. This compound reduced Nbenzyl-(1-phenyletilidene)amine with 27% enantiomeric excess

ASSUNTO(S)

iminas - redução boroidreto de sodio aminas quirais boroidreto quiral imine reduction sodium borohydride chiral amines chiral borohydride

ACESSO AO ARTIGO

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