There was concern whether the flash epimerization at high temperatures would be feasible given the dense functionalization of the API (free amine, electrophilic benzene ring, cyclopropyl moiety). As such, flash epimerization was first studied in batch using microwave irradiation. Rapid heating of mother liquors showed full epimerization of substrate within 4 minutes at 160 °C, and generation of related impurities appeared to be encouragingly low.