Evidence of Al<sup>II</sup>Radical Addition to Benzene
Debdeep Mandal, T. Ilgin Demirer, Tetiana Sergeieva, Bernd Morgenstern, Haakon T. A. Wiedemann, Christopher W. M. Kay, Diego M. Andrada
Abstract
Abstract Electrophilic Al III species have long dominated the aluminum reactivity towards arenes. Recently, nucleophilic low‐valent Al I aluminyl anions have showcased oxidative additions towards arenes C−C and/or C−H bonds. Herein, we communicate compelling evidence of an Al II radical addition reaction to the benzene ring. The electron reduction of a ligand stabilized precursor with KC 8 in benzene furnishes a double addition to the benzene ring instead of a C−H bond activation, producing the corresponding cyclohexa‐1,3(orl,4)‐dienes as Birch‐type reduction product. X‐ray crystallographic analysis, EPR spectroscopy, and DFT results suggest this reactivity proceeds through a stable Al II radical intermediate, whose stability is a consequence of a rigid scaffold in combination with strong steric protection.