Development and Scale-Up of an Optimized Route to the Peptide Boronic Acid, CEP-18770

CEP-18770 is an unstable peptide boronic acid and an amorphous solid, making it a challenging synthetic target. Process R&D led to a new process that avoided chromatography through crystalline intermediates, increased atom and volume efficiency, provided a chromophore, and gave higher yields and purity. A stable, crystalline diethanolamine adduct was discovered that has the potential to be used as a prodrug.