Intermolecular cyclization of N-methylanilines and maleimides to tetrahydroquinolines via K2S2O8 promoted C(sp3)-H activation

A metal-free, novel and convenient way for the direct cyclization of N-methylanilines with maleimides to tetrahydroquinolines via C(sp(3))-H activation is reported. The protocol utilizes inexpensive and easy to handle K2S2O8 as a radical surrogate and involves sequential formation of C(sp(3))-C(sp(2)) and C(sp(2))-C(sp(2)) bonds in a one-pot procedure at room temperature. The method affords excellent yield of tricyclic compounds incorporating biologically important tetrahydroquinoline core. (C) 2016 Elsevier Ltd. All rights reserved.