Asymmetric Olefin Isomerization of Butenolides via Proton Transfer Catalysis by an Organic Molecule

An unprecedented enantioselective and general olefin isomerization was realized via biomimetic proton transfer catalysis with a new chiral organic catalyst. A broad range of mono- and disubstituted beta,gamma-unsaturated butenolides were transformed into the corresponding chiral alpha,beta-unsaturated butenolides in high enantioselectivity and yield in the presence of as low as 0.5 mol % catalyst. Mechanistic studies have revealed the protonation as the rate-determining step.