title: An efficient preparation of N-methyl-alpha-amino acids from N-nosyl-alpha-amino acid phenacyl esters.
abstract: In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids. This represents a very important application in peptide synthesis to obtain N-methylated peptides in both solution and solid phase. The developed methodology involves the use of N-nosyl-alpha-amino acids with the carboxyl function protected as a phenacyl ester and the methylating reagent diazomethane. An important aspect of this synthetic strategy is the possibility to selectively deprotect the carboxyl function or alternatively both amino and carboxyl moieties by using the same reagent with a different molar excess and under mild conditions. Furthermore, the adopted procedure keeps unchanged the acid-sensitive side chain protecting groups used in Fmoc-based synthetic strategies.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università della Calabria, Via Ponte P. Bucci Cubo 15/C, I-87036 Arcavacata di Rende (CS), Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Leggio
authors.forename: Emilia Lucia
authors.initials: EL
authors.lastname: Belsito
authors.forename: Rosaria
authors.initials: R
authors.lastname: De Marco
authors.forename: Angelo
authors.initials: A
authors.lastname: Liguori
authors.forename: Francesca
authors.initials: F
authors.lastname: Perri
authors.forename: Maria Caterina
authors.initials: MC
authors.lastname: Viscomi
mesh_terms: D000098:Acetophenones / Q000737:chemistry*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004952:Esters; D007202:Indicators and Reagents / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000098:Acetophenones; D000596:Amino Acids; D004952:Esters; D007202:Indicators and Reagents; D010455:Peptides; D012996:Solutions