9‑Silafluorenes via Base-Promoted Homolytic Aromatic Substitution (BHAS) – The Electron as a Catalyst

Transition-metal-free intramolecular radical silylation of 2-diphenyl­silylbiaryls via base-promoted homolytic aromatic substitution (BHAS) to give 9-silafluorenes is reported. 2-Diphenyl­silylbiaryls are readily prepared, and cross dehydrogenative silylation occurs with <i>tert</i>-butylhydro­peroxide (TBHP) as a cheap stoichiometric oxidant in the presence of a small amount of tetra­butyl­ammonium iodide (TBAI) as an initiator. These cyclizations are catalyzed by the electron

Cross Dehydrogenative Coupling via Base-Promoted Homolytic Aromatic Substitution (BHAS): Synthesis of Fluorenones and Xanthones

Cross dehydrogenative coupling reactions occurring via base-promoted homolytic aromatic substitutions (BHASs) are reported. Fluorenones and xanthones are readily prepared via CDC starting with readily available <i>ortho</i>-formyl biphenyls and <i>ortho</i>-formyl biphenylethers, respectively. The commercially available and cheap <i>t</i>BuOOH is used as an oxidant. Initiation of the radical chain reaction is best achieved with small amounts of FeCp₂ (0.1 or 1 mol %)

6‑Aroylated Phenanthridines via Base Promoted Homolytic Aromatic Substitution (BHAS)

Readily accessible 2-isocyanobiphenyls react with aromatic aldehydes via base promoted homolytic aromatic substitution (BHAS) to give 6-aroylated phenanthridines. Reactions occur via addition of acyl radicals to the isonitrile functionality and subsequent intramolecular BHAS of the intermediate imidoyl radicals. Initiation of the radical chain reaction is best achieved with small amounts of FeCl₃ (0.4 mol %), and the commercially available and cheap <i>t</i>BuOOH is used as the oxidant