Improved synthesis of C-terminal peptide thioesters on safety-catch resins using LiBr/THF

GRAPHICS The alkanesulfonamide safety-catch resin has proven useful for Fmoc-based synthesis of C-terminal peptide thioesters. We now report that the yield of isolated thioester can increase significantly when the cleavage reaction is carried out in 2 M LiBr/THF rather than DMF or THE The largest effects are seen with problematic peptides that aggregate or form secondary structures on the resin.