Gold-catalyzed oxa-Povarov reactions for the synthesis of highly substituted dihydrobenzopyrans from diaryloxymethylarenes and olefins

Abstract

Oxa-Povarov reactions involving readily available diaryloxymethylarenes and aryl-substituted alkenes are reported. Their [4+2] cycloadditions were efficiently catalyzed by IPrAuSbF6 (IPr=1,3-bis(diisopropylphenyl)imidazol-2-ylidene) with high diastereoselectivity. Product analysis revealed that the reactions likely proceed by a stepwise ionic mechanism, because both E- and Z-configured β-methylstyrene gave the same cycloadducts in the same proportions.

Keywords: cycloaddition; diastereoselectivity; gold; oxygen heterocycles; synthetic methods.