Synthesis of substituted 2,5-dihydro-2,2'-bifurans

Extended Version of the Corey–Chaykovsky Reaction: Synthesis of 2,4-Substituted Furans by the Treatment of β-Dialkylamino Chalcones with Dimethylsulfonium Methylide

“…Recently, we have found that in the reaction of β,β-diaryl-α,β-unsaturated ketones with DMSM, vinyloxiranes were not products but intermediates undergoing the ring expansion without any added catalyst affording trisubstituted 2,5-dihydrofurans . This process can be referred to as the extended Corey–Chaykovsky reaction .…”

“…11 Recently, we have found that in the reaction of β,β-diarylα,β-unsaturated ketones with DMSM, vinyloxiranes were not products but intermediates undergoing the ring expansion without any added catalyst affording trisubstituted 2,5dihydrofurans. 12 This process can be referred to as the extended Corey−Chaykovsky reaction. 13 Its realization is presumably resulted from the heterolysis of the C−O bond in the formed vinyloxiranes due to the excellent stabilization of the cationic center in the zwitter-ionic intermediate.…”