VO(acac)2/TBHP Catalyzed Epoxidation of 2-(2-Alkenyl)phenols. Highly Regio- and Diastereoselective Oxidative Cyclization to 2,3-Dihydro-benzofuranols and 3-Chromanols

Abstract

The VO(acac) 2 /TBHP (1.5 mol%/1.3 equiv) system has been successfully used for the epoxidation of variously double bond substituted 2-(2-alkenyl)phenols under mild conditions. Moreover, a one-pot conversion to 2,3-dihydrobenzofuranols and 3-chromanols is achieved with high or complete regio- and diastereoselectivity in the presence of catalytic amounts of TFA (20 mol%). This metal-catalyzed methodology was shown to be more practical and superior to the previously employed m-CPBA for the epoxidation and the oxidative cyclization of 2-(2-alkenyl)phenols.