Synthesis of 2,3‐Diarylindanones and 2‐Arylindenes from Trisubstituted α,β‐Unsaturated Esters Derived from Highly Strained 2,3‐Diarylcyclopropenones by Ring Opening with Coumarin Derivatives

Abstract A novel strategy has been developed for the synthesis of 2,3‐diarylindanones and 2‐arylindenes through the formation of trisubstituted α,β‐unsaturated esters by the ring opening of 2,3‐diarylcyclopropenones in the presence of a catalytic amount of TPP under mild reaction conditions. Initially, PPh 3 activates the diarycyclopropenone to generate the phosphonium adduct, which simultaneously reacts with 4‐hydroxycoumarins to afford α,β‐unsaturated esters instead of Wittig olefination. Subsequently, these α,β‐unsaturated esters undergo a smooth Friedel–Crafts‐type cyclization with arenes in the presence of AlCl 3 to give a new series of 2,3‐diarylindanones in good to excellent yields. Additionally, the reduction of α,β‐unsaturated esters with NaBH 4 followed by acid‐catalyzed cyclization of the resulting allylic alcohols afforded 2‐arylindenes in good yields. This is the first report on the use of α,β‐unsaturated esters as precursors for the synthesis of diarylindanones and arylindenes.