A Practical Synthesis of the Pseudotripeptide RC-1291

The rapid process development of a scaleable synthesis of the pseudotripeptide RC-1291 for preclinical and clinical evaluation is described. By employing a nontraditional N-to-C coupling strategy, the peptide chain of RC-1291 was assembled in high yield, with minimal racemization and in an economical manner by introducing the most expensive component last. A one-pot deprotection/crystallization procedure was developed for the isolation of RC-1291 free base, which afforded the target compound in excellent yield and with a purity of >99.5% without chromatographic purification.