Ionic liquid for protection of amino acids and peptides

What is it about?

The use of ionic liquids allows for a rapid and clean removal of the 4-nitrobenzenesulfonyl (nosyl) group and for the facile subsequent tert-butyloxycarbonylation of the free α-amino function under very mild conditions. Here, we present a one-pot procedure for the sequential deprotection/reprotection of the amino function of amino acid and peptide methyl esters in [bmim][BF4].

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Photo by Alex Kondratiev on Unsplash

Photo by Alex Kondratiev on Unsplash

Why is it important?

Protection of the α-amino functionality of amino acids is one of the most important issues in peptide synthesis and it is mandatory to prevent polymerization of the amino acid once it is activated. The advantages of the protocol are mild conditions, very short reaction time, the ease of extraction of products from IL, excellent yields and purities, absence of racemization/epimerization and the IL recyclability. The process appears charming and highly versatile, representing a valuable tool for the easy removal of 4-nitrobenzenesulfonyl group as well as for the introduction of the Boc moiety.