The Synthesis of Acenes by Mechanochemical Reductive Aromatization

A Sn-mediated mechanochemical reductive aromatization of 1,4-dihydroxy- and 1,4-dimethoxy-cyclohexadienes has been used to form ten acenes, including derivatives of benzene, anthracene, tetracene, and pentacene. This method has been developed to overcome issues faced during the formation of electron-deficient 1,4-dihydroxy- or 1,4-dimethoxy-cyclohexadienes under homogeneous conditions. While this method does not tolerate trimethylsilyl protecting groups for alkynes, it can provide a fast, easy to set up alternative to homogeneous reductive aromatization.