One-Pot Cascade Trifluoromethylation/Cyclization of Imides: Synthesis of α‑Trifluoromethylated Amine Derivatives

Tryptamine-
and phenethylamine-derived imides were selectively
monotrifluoromethylated using CF3TMS. Subsequent methanesulfonic
acid mediated cyclization of the intermediate hemiaminals afforded
the α-trifluoromethylated amine derivatives via the formation
of trifluoromethylated acyliminium ions, in one pot. The strategy
was applicable to the both inter- and intramolecular versions. Furthermore,
the utility of the present method was demonstrated through the synthesis
of trifluoromethylated analogues of harmicine and crispine A.