title: Optimized selective N-methylation of peptides on solid support.
abstract: Peptides containing N(alpha)-methylamino acids exhibit interesting therapeutic profiles and are increasingly recognized as potentially useful therapeutics. Unfortunately, their synthesis is hampered by the high price and nonavailability of many N(alpha)-methylamino acids. An efficient and practical three-step procedure for selective N-methylation of peptides on solid support is described. The procedure was based on the well known solid-phase N-methylation of N(alpha)-arylsulfonyl peptides, which was improved by using dimethylsulfate and the less expensive DBU as base. Every step of the procedure, amine activation by an o-nitrobenzenesulfonyl group, selective N-methylation and removal of the sulfonamide group, was optimized in respect of time and economy. The described optimized three-step procedure is performed in 35 min without solvent changes, instead of 3 h. Tripeptides (Fmoc-Phe-MeXaa-Leu-OH) containing N-methylated common amino acids were also prepared using the optimized procedure to demonstrate its compatibility with these amino acids. The described procedure allows an efficient synthesis of N(alpha)-methylamino acid containing peptides in a very short time using Fmoc solid-phase peptide synthesis.
authors.affiliation: Department Chemie, Lehrstuhl II für Organische Chemie, Technische Universität München, Germany.
authors.forename: Eric
authors.initials: E
authors.lastname: Biron
authors.forename: Jayanta
authors.initials: J
authors.lastname: Chatterjee
authors.forename: Horst
authors.initials: H
authors.lastname: Kessler
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D008745:Methylation; D015394:Molecular Structure; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry; D013997:Time Factors
chemical_list: D000596:Amino Acids; D010455:Peptides