Abstract: Provided are N-(9-fluorenylmethoxycarbonyl)-4-substituted proline derivatives represented by the following formula (I): ##STR1## wherein Q is O or S, R represents a particular monovalent group, and T represents H or --C(CH.sub.3).sub.3. Where T is H, the derivatives can each be prepared by reacting a corresponding electron attractive compound with N-(9-fluorenylmethoxycarbonyl)-4-hydroxyproline in the presence of a coupling reagent. The derivatives in which T stands for --(CH.sub.3).sub.3 can each be prepared by reacting the corresponding N-(9-fluorenylmethoxy-carbonyl)-4-hydroxyproline derivative with isobutylene in the presence of a catalytic amount of sulfuric acid. The staring material, N-(9-fluorenylmethoxycarbonyl)-4-hydroxyproline, can be purified by adsorbing it on anhydrous magnesium sulfate.