Hydrolysis of physostigmine (I) with either NaOMe in ethanol or NaOBu in refluxing butanol (better yield) gives eseroline (II), which is condensed with phenyl isocyanate (III) by means of NaOMe in benzene, Na in benzene or Na in ether/benzene.
The title carbamate was prepared by condensation of (-)-eseroline (I) with 4-isopropylphenyl isocyanate in Et2O in the presence of a catalytic amount of Na.