Deprotection/reprotection of the amino group in α-amino acids and peptides. A one-pot procedure in [Bmim][BF<sub>4</sub>] ionic liquid
作者:M. L. Di Gioia、A. Barattucci、P. Bonaccorsi、A. Leggio、L. Minuti、E. Romio、A. Temperini、C. Siciliano
DOI:10.1039/c3ra46599c
日期:——
of the α-amino group in α-aminoacid and dipeptide methyl esters. [Bmim][BF4] is used as the solvent in the entire process. In particular, the use of the ionicliquid allows for rapid and clean removal of the 4-nitrobenzenesulfonyl (nosyl) group and for facile subsequent tert-butyloxycarbonylation of the free α-amino function under very mild conditions. N-Boc-α-amino acid as well as peptide derivatives
N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates
作者:Rosaria De Marco、Maria Luisa Di Gioia、Angelo Liguori、Francesca Perri、Carlo Siciliano、Mariagiovanna Spinella
DOI:10.1016/j.tet.2011.10.042
日期:2011.12
tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N-ethyl derivatives of N-arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied
An Efficient Preparation of <i>N</i>-Methyl-α-amino Acids from <i>N</i>-Nosyl-α-amino Acid Phenacyl Esters
作者:Antonella Leggio、Emilia Lucia Belsito、Rosaria De Marco、Angelo Liguori、Francesca Perri、Maria Caterina Viscomi
DOI:10.1021/jo901643f
日期:2010.3.5
In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-α-amino acids and N-Fmoc-N-methyl-α-amino acids. This represents a very important application in peptidesynthesis to obtain N-methylated peptides in both solution and solidphase. The developed methodology involves the use of N-nosyl-α-amino acids with the carboxyl function protected as a phenacyl ester and