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
Deprotection of<i>N</i>-Nosyl-α-amino Acids by Using Solid-Supported Mercaptoacetic Acid
作者:Rosaria De Marco、Maria Luisa Di Gioia、Antonella Leggio、Angelo Liguori、Maria Caterina Viscomi
DOI:10.1002/ejoc.200900271
日期:2009.8
has been developed. Mercaptoaceticacid was first protected by the dimethoxytrityl group and then anchored to Wang resin through an ester bond. Deprotection of the thiol function led to resin-supported mercaptoaceticacid, a useful supported thiol reagent that can be used in the polymer-assisted solution-phase removal of nosyl (Ns) groups from the amino function of α-amino acids in peptide synthesis
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