Iridium-Catalyzed <i>Z</i>-Selective Asymmetric Allylic Substitution Reaction via <i>Z</i>/<i>E</i> Kinetic Resolution
Yi‐Ming Hou, Ru Jiang, Jiandong Liu, Chao Zheng, Shu‐Li You
Abstract
Chiral Z -olefin molecules are much more challenging targets in organic synthesis due to their thermodynamically unfavorable nature compared with that of their corresponding E -olefin counterparts. Particularly, the transformations toward advanced chiral Z -olefin products from readily available E -olefin precursors are faced with huge difficulties associated with the energetic uphill process. A possible solution to this issue is taking advantage of the different kinetic behaviors between Z - and E -olefins. However, recognizing the different reactivities between Z - and E -olefins poses great challenges for molecular catalysis. Herein, we report an Ir-catalyzed Z -selective asymmetric allylic substitution using oxindoles as nucleophiles via the kinetic resolution of Z / E olefin mixtures. The higher reactivity of Z -allylic carbonates than their E -counterparts in this reaction manifold originates from the faster oxidative addition of Z -allylic carbonates to the Ir(I) catalyst and the faster nucleophilic attack to anti -π-allyl-Ir intermediates than that to syn -π-allyl-Ir intermediates by external nucleophiles. When coupled with photoinduced olefin E / Z isomerization, the same products are accessed from E -allylic carbonates in up to 97% yield with 96% ee and >19:1 Z / E ratio. The results reported in this study represent an unprecedented pattern in asymmetric Tsuji–Trost-type reactions, a class of fundamental transformations in organic synthesis, and provide a unique approach to advanced chiral Z -olefins.