SIDE REACTIONS IN PEPTIDE SYNTHESIS:

Abstract

Acylation of amino acid β‐naphthylamides with protected (Boc) amino acid‐isobutylcarbonic acid mixed anhydrides resulted in each case in the formation of some undesired by‐product: an isobutyloxycarbonylamino acid β‐naphthylamide. The amount of this second acylation product was particularly high, with the hindered amino acids valine and isoleucine as carboxyl‐components. The nature of the amino component had no major influence on the extent of this side reaction.