A concise synthesis of physostigmine from skatole and activated aziridine via alkylative cyclization.

A concise synthetic route to physostigmine has been developed, where the key step relies on the alkylative cyclization of 1,3-dimethylindole with (Z)-aziridine catalyzed by Sc(OTf)3 and TMSCI in dichloromethane at -30 degrees C, to give 8 in 90% yield, which, in turn, can be readily converted into physostigmine.