Recrystallise these chiral imidazolinones from boiling EtOH (solubility is 1.43g/mL) or better by dissolving in CH2Cl2 and adding pentane, filtering and drying for at least 12hours at 60o/0.1mm and sublime them at 135o/0.01mm. They have also been purified by flash column chromatography through Merck silica gel at 0.04-0.063mm and using Et2O/pet ether/MeOH (60:35:5) as eluent. They are then recrystallised from EtOH/pet ether. [IR, NMR: Seebach et al. Helv Chim Acta 70 237 1987, Fitzi & Seebach Angew Chem, Int Ed Engl 25 345 1986.] The racemate is purified in a similar manner and has m 104-105o [NMR: Seebach et al. Helv Chim Acta 68 949 1985].
