Connecting Organic Redox‐Active Building Blocks through Mild Noncatalytic C−H Activation

Abstract

AbstractCompounds with two or more redox‐active units, connected by a bridge that supports electronic coupling between the units, have been studied for a long time. Redox reactions could result in mixed‐valence compounds, in which the electronic structure depends on the degree of electronic coupling. Here we report the synthesis of the first molecule in which two redox‐active guanidines are connected through a bridge. The compound is synthesized in an unprecedented, simple one‐step procedure involving an atom‐economically favorable, non‐catalytic C−H activation reaction at room temperature from novel 1,2,4‐trisguanidino‐benzene molecules and 1,4‐benzenedithiol. We then apply similar protocols to introduce other substituents in 5‐position of a 1,2,4‐trisguanidino‐benzene molecule, demonstrating the scope of these exceptional C−H activation reactions. Finally, we report the synthesis of a hexakisguanidino‐biphenyl by direct coupling of two trisguanidino‐benzene units through C−H activation. Its oxidation leads to the first mixed‐valence compound with charge delocalization between two redox‐active guanidino units. The redox states of the resulting novel compounds are systematically studied.