Treatment of lactone (I) with methanesulfonyl chloride, followed by reaction with methylamine furnishes amide (II). This is subsequently cyclized to the benzoindolone derivative (III) in the presence of AcOH in acetonitrile. The acetate group of (III) is then displaced by a methoxy group to give (IV) upon heating in MeOH. Finally, condensation of (IV) with propyl isocyanate (V) provides the title N-propyl carbamate.