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.