Asymmetric Olefin Isomerization of Butenolides

Significance

Deng and co-workers describe an asymmetric olefin isomerization of butenolides via proton-transfer catalysis using catalysts 1 and 2. The authors developed new cinchona-derived catalysts 1 and 2, and these catalysts gave the products in high enantioselectivities and good yields. A proposed mechanism was shown, and this catalytic cycle is comparable to the enzyme-mediated isomerization of steroidal ketones. To prove the reaction mechanism, the authors carried out preliminary kinetic studies and kinetic-isotope-effect experiments and the protonation step turned out to be the rate-determining step.