Sc(OTf)3 Catalyzed [4 + 2]-Annulation Reaction between Electron-Rich Phenols and Donor-Acceptor Cyclopropanes: Synthesis of Polysubstituted Dihydronaphthols.

On the basis of the Lewis acid-catalyzed Friedel-Crafts alkylation between 1-acyl-2-arylcyclopropanecarboxylate esters and electron-rich phenols, a Sc(OTf)3 catalyzed cascade [4 + 2]-annulation reaction was developed for the direct synthesis of polysubstituted dihydronaphthols from phenols. In this reaction, the structure of products is dominated by the directing effect of the substituent groups on phenols. Meanwhile, a one-pot Friedel-Crafts alkylation/oxidative cyclization reaction was also developed for the synthesis of spiro-fused 2,5-cyclohexadienones.