A Solid‐Phase Approach to Accessing Bisthioether‐Stapled Peptides Resulting in a Potent Inhibitor of PRC2 Catalytic Activity

: Stapled peptides have emerged as a new class of therapeutics to effectively target intractable protein-protein interactions. Thus, efficient and versatile methods granting easy access to this class of compounds and expanding the scope(s) of the currently available ones are of great interest. Now, a solid phase approach is described for the synthesis of bisthioether stapled peptides with multiple architectures, including single-turn, double-turn, and double-stapled macrocycles. This method allows for ligation with all-hydrocarbon linkers of various lengths, avoiding the use of unnatural amino acids and expensive catalysts, and affords cyclopeptides with remarkable resistance to proteolytic degradation. The potential of this procedure is demonstrated by applying it to generate a stapled peptide that shows potent in vitro inhibition of methyltransferase activity of the polycomb repressive complex 2 (PRC2) of proteins.