Challenge toward structural complexity using asymmetric catalysis: Target-oriented development of catalytic enantioselective Diels-Alder reaction

A new method for the catalytic enantioselective Diels-Alder reaction using polysubstituted silyl enol ethers as dienes is described. High enantioselectivity (up to 92% ee) was produced using a catalyst generated from FeBr3 and AgSbF6 in a 1:2 ratio and aryl-pybox (aryl = Ph or p-ethoxyphenyl). This reaction should facilitate the enantioselective synthesis of polycyclic acylphloroglucinois such as hyperforin or garsubellin A, which are currently of interest from synthetic and medicinal points of view.