Peptide coupling using recyclable bicyclic benziodazolone

We report a greener peptide coupling using bicyclic benziodazolone and triarylphosphine as coupling reagents. Bicyclic benziodazolone also works as a base and can be recovered as the corresponding iodine(i) compound after use, which can be converted to the original iodine(iii) reagent by electrolytic oxidation. This study provides a greener peptide coupling method using triarylphosphine and recyclable bicyclic benziodazolone, which acts as an oxidant for phosphine as well as base.