Chemoselective alkylation of N-alkylaminooxy-containing peptides.

Peptides containing N-alkylaminooxy amino acids were chemoselectively alkylated with allylic, benzylic, and alpha-carbonyl bromides, N-ethylmaleimide, and hexyl acrylate in mildly acidic aqueous/organic solutions. Alkylation at the aminooxy nitrogen proceeds in good yields with excellent to complete chemoselectivity in the presence of all common amino acids except cysteine. This reaction complements the selective glycosylation and acylation of N-alkylaminooxy groups and provides an avenue for the synthesis of peptide arrays comprising a wide variety of neoglycopeptides and neolipopeptides.