Phosphine-Catalyzed Domino Reaction for the Synthesis of Conjugated 2,3-Dihydrofurans from Allenoates and Nazarov Reagents

A new domino reaction for Nazarov reagents: An efficient approach was developed for the construction of highly functionalized conjugated 2,3‐dihydrofuran skeletons. Nazarov reagents were used for the first time in a phosphine‐catalyzed domino reaction and successfully used to construct five‐membered ring compounds using alcohol as the solvent. DFT calculations indicate that alcohol is essential for the catalysis of the [1,2]‐proton transfer.