Regioselective Synthesis of Arylsulfonyl Benzophenones via Aerobic Oxidative [3+3] Benzannulation Reactions

Abstract

Regioselective synthesis of 3‐arylsulfonyl benzophenone derivatives via base mediated, aerial‐oxidative [3+3] benzannulation of α,β‐unsaturated aldehydes and 4‐sulfonyl butenones is reported. A variety of readily available acyclic building blocks are transformed into substituted biaryl ketones in this benzannulation reaction. The reaction proceeds under mild conditions in an open flask and uses atmospheric oxygen as oxidant to afford good yields of the products. Analogous benzannulation reactions of chalcone afforded highly substituted m‐terphenyl‐benzophenone derivatives.

One-Pot Synthesis of Multiarylated Benzophenones via [3 + 2 + 1] Benzannulation of Ketones, Alkynes, and α,β-Unsaturated Carbonyls

“…An undesired self-condensation product and a presumably polymerized product were also observed by GC-MS and NMR analysis of the crude mixture. Unlike Menon’s report on benzannulation in 2020, our initial attempt unfortunately obtained a low yield of the desired product 4aa . We supposed that in Menon’s system, the electron-withdrawing sulfonyl group at the γ-position in the transient β,γ-unsaturated ketone intermediate stabilizes the dienolate, preventing the formation of undesired products.…”

“…π-Extended benzophenones are attractive structural units because they show interesting photoinduced properties. Many synthetic methods for benzophenones have been developed so far . Conventionally, benzophenones are synthesized by Friedel–Crafts acylation of benzoyl halides and aromatic compounds .…”

“…Aromatic rings can be constructed from acyclic components to synthesize a diverse range of aromatic compound . In 2020, Menon et al reported that γ-sulfonyl β,γ-unsaturated ketones reacts with cinnamyl aldehydes and chalcone to give arylsulfonyl benzophenones with 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU) (Scheme b) . Menon et al.…”