Synthesis Of2,5-diphenylfurans Promoted By Photoredox Catalysis

Substituted furans are a structural component of a vast number of biologically ac-tive natural and non-natural compounds. They also have been found to be key structuralcomponents in abundant naturally occurring products, important intermediates in indus-trial organic syntheses, such as pharmaceuticals, and material sciences. Consequently,synthesis of various furans has been a research objective for over a century, and a vari-ety of well-established methods are available in the literature, including classical reac-tions under either acidic or basic conditions, the transitionmetal-catalyzed have attractedincreasing attention. But it rarely available report the synthesis of2,5-diphenylfuranpromoted by photoredox catalysis.As environmental and ecological problems increasingly prominent along with theindustrial development, the concept of green chemistry is gradually thorough accepted.Approaches to channel visible light into organic molecules with the use of photoredoxcatalysts are more important than ever to meet the challenge of enviromental sustaina-bility. This article develops a new method for the synthesis of2,5-diphenylfuran via thephotoredox.Via simple Claisen-Schmidt condensation and Johnson-Corey-Chaykovsky re-action with the raw materials of commercially available acetophenones and benz-aldehydes, it affords the substrate2-phenylcyclopropylphenylmethanone. Reactionscarry out with oxidant carbon tetrabromide, efficient auxiliary lithelloum bromide,then irradiated by blue LED light with photoredox catalysis. The reaction occursunder mild reaction conditions, do not need air-and moisture-free, to afford2,5-diphenylfuran. Also noteworthy is that unsymmetrically2,5-disubstituted3-borofu-rans can be provided with excellent regiocontrol when the oxidant increased.Furthermore, the possible mechanism is proposed on the basis of the rearrange-ment intermediate β,γ-unsaturated ketone. Excited state*RuIIinduced by the carbontetrabromide via oxidative quenching generates an radical cation to afford the final2,5-dipenylfuran after rearrangement and oxidative dehydrogenation.