Just add water: a new fluorous capping reagent for facile purification of peptides synthesized on the solid phase.

A novel fluorous capping reagent is introduced to facilitate purification during solid-phase peptide synthesis (SPPS). Reagent 1 is a trivalent iodonium salt that reacts vigorously with free amines to deliver a long-chain fluoroalkyl group. It has been used to tag all unreacted amines following the peptide coupling step in SPPS. The resulting fluoroalkylated amine is no longer able to couple in further peptide coupling steps and is also stable to standard peptide synthesis conditions. Deletion products are removed using flash fluorous chromatography to yield the pure, full-length peptide.