Visible‐light‐mediated Synthesis of Bromo‐containing Azaspirotrienediones from N ‐phenylpropynamides

Abstract A visible‐light‐mediated reaction of N ‐phenylpropynamides with diethyl 2,2‐dibromomalonate for the synthesis of bromo‐substituted azaspirotrienediones has been developed. This method allows the formation of C−Br, C−C and C=O bonds in one pot via a cascade radical addition/ipso‐cyclization/oxidation process. A possible radical mechanism involving single electron transfer and energy transfer processes is proposed based on control experiments, cyclic voltammetry determination and Stern‐Volmer quenching experiments.