Publicação
C-terminal amide bond stability of peptides containing C,alfa,alfa-disubstituted glycines
| Resumo: | We have since long been interested in the synthesis of C,alfa,alfa-disubstituted glycines using the Ugi Four Component Condensation Reaction. Recently we have improved this method of synthesis by using 4-methoxybenzyl amine as the amine component of the Ugi reaction (A), which allowed an important simplification in the subsequent cleavage of the product. During the removal of the 4-methoxybenzyl group with hot neat TFA, we detected that not only this group was removed but also the C-terminal amide bond was cleaved. This result was independent of the nature of the amino acid residue so far generated and of the N-substituent at the C-terminal amide group. After work-up in aqueous media, the N-acetyl amino acids were isolated in quantitative yield. A similar behaviour was reported by Goodman et al., but with dimethylglycine derivatives having a methyl group at the nitrogen atom of this residue. In our case cleavage appears to occur even after removal of the N-alkyl group. These results prompted us to a further thorough study of the stability of this peptide bond under different conditions, by changing the acid used and the temperature of the reaction mixture. |
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| Autores principais: | Lima, Sílvia M. M. A. Pereira |
| Outros Autores: | Costa, Susana P. G.; Maia, Hernâni L. S. |
| Assunto: | Amide bond C,alfa,alfa-disubstituted glycines Stabylity Ugi-Passerini Reaction |
| Ano: | 2001 |
| País: | Portugal |
| Tipo de documento: | outro |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | We have since long been interested in the synthesis of C,alfa,alfa-disubstituted glycines using the Ugi Four Component Condensation Reaction. Recently we have improved this method of synthesis by using 4-methoxybenzyl amine as the amine component of the Ugi reaction (A), which allowed an important simplification in the subsequent cleavage of the product. During the removal of the 4-methoxybenzyl group with hot neat TFA, we detected that not only this group was removed but also the C-terminal amide bond was cleaved. This result was independent of the nature of the amino acid residue so far generated and of the N-substituent at the C-terminal amide group. After work-up in aqueous media, the N-acetyl amino acids were isolated in quantitative yield. A similar behaviour was reported by Goodman et al., but with dimethylglycine derivatives having a methyl group at the nitrogen atom of this residue. In our case cleavage appears to occur even after removal of the N-alkyl group. These results prompted us to a further thorough study of the stability of this peptide bond under different conditions, by changing the acid used and the temperature of the reaction mixture. |
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