On the selective N-methylation of BOC-protected amino acids

  • J Org Chem. 2009 Nov 6;74(21):8425-7. doi: 10.1021/jo9016293.
Andrei V Malkov  1 ,  Kvetoslava Vranková ,  Miloslav Cerný ,  Pavel Kocovský
Affiliations
  • 1. Department of Chemistry, WestChem, University of Glasgow, Glasgow G12 8QQ, UK. [email protected]
PMID: 19821609 DOI: 10.1021/jo9016293
Abstract

The selective N-methylation of BOC-protected valine 1a 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 N-H bond, has been ruled out by isotopic labeling.

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