Palladium-Catalyzed Diastereo- and Enantioselective Formal [3 + 2]- Cycloadditions of Substituted Vinylcyclopropanes

摘要

We describe a palladium-catalyzed diastereo- and enantioselective formal [3 + 2]-cycloaddition between substituted vinylcyclopropanes and electron-deficient olefins in the form of azlactone- and Meldrum's acid alkylidenes to give highly substituted cyclopentane products. By modulation of the electronic properties of the vinylcyclopropane and the electron-deficient olefin, high levels of stereoselectivity were obtained. The remote stereoinduction afforded by the catalyst, distal from the chiral pocket generated by the Iigand, is proposed to be the result of a new mechanism invoking the Curtin-Hammett principle.