On the Selective N-Methylation of BOC-Protected Amino Acids

Abstract

The selective N-methylation of BOC-protected valine with MeI and NaH in THF (i.e., in the presence of a free carboxyl group) has been attributed to the protection of the carboxylate by chelation to Na+. An alternative mechanism, involving the formation of the carbene intermediate generated from MeI and its insertion into the NMINUS SIGN H bond, has been ruled out by isotopic labeling.

Keywords

• polymer-supported organocatalysts
• asymmetric reduction
• methylamino acids
• peptide-synthesis
• enantioselective reduction
• enantiomeric purity
• aromatic ketimines
• trichlorosilane
• imines
• derivatives