3-Phenylquinolin-2-thione (2.5 g.) was added to a suspension of sodium hydride (0.55 g. of a 50% w/w dispersion in mineral oil) in dimethylformamide (16 ml.) at 0°-5°. When all the hydrogen had evolved, (S)-2-t-butoxycarbonylamino-1-p-toluenesulphonyloxypropane (3.5 g.) was added and the mixture was stirred at ambient temperature for 16 hr. The mixture was then poured into ice-water (160 ml.) and extracted with ethyl acetate (3×50 ml.). The ethyl acetate extract was washed with brine (50 ml.) and then dried (MgSO4). The solvent was evaporated and the residue was crystallised from petroleum ether to give (S)-2-(2-t-butoxycarbonylaminopropylthio)-3-phenylquinoline, m.p. 86°-7°.
