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.