Visible-Light-Induced\nCopper-Catalyzed Radical Reactions\nof Diazo Arylidene Succinimides to Access the Pyromellitic Diimide\n(PMDI) Core

The\nsynthesis of pyromellitic diimides (PMDIs) through visible-light-promoted\ncopper-catalyzed reaction of diazo arylidene succinimides has been\naccomplished without the use of external oxidants. This transformation\ninvolves a carbon radical from diazo arylidene succinimides with a\ncopper catalyst or photocatalyst via the proton-coupled electron transfer\n(PCET) process. This approach successfully challenges a long-standing\nparadigm in the synthesis of PMDIs. Notably, copper complex (CuNCS)\nformed in situ proved to be playing a pivotal role to drive the reaction\nvia photoinitiation. Additionally, we synthesized a PMDI molecule\nknown for its prominent aggregation-induced emission (AIE) property.\nFor the very first time, we have synthesized unsymmetrical PMDIs\nby employing the developed protocol.