Benzeneseleninic acid used as an oxidizing and deprotecting reagent for the synthesis of multi-cyclic peptides constrained by multiple disulfide bonds and thioether bridges

New methodologies based on benzeneseleninic acid (BSA) were designed to efficiently synthesize multiple disulfide bonds or thioether bridges in peptides in a one-pot manner in which BSA dually functioned as an oxidant and a deprotecting reagent.