Zwitterion-Catalyzed Isomerization of Maleic to Fumaric Acid Diesters
Ying-Pong Lam, Zachary Lam and Ying-Yeung Yeung*
*Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, Email: yyyeungcuhk.edu.hk
Y.-P. Lam, Z. Lam, Y.-Y. Yeung, J. Org. Chem., 2021, 86, 1183-1190.
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Zwitterionic organocatalysts with an amide anion/iminium cation charge pair catalyze the isomerization of maleic acid diesters to give fumaric acid diesters. Whereas the cooperative effect of the charges lower the activation barrier for a Michael addition of the catalyst to the substrate, the key interaction results from a nonclassical hydrogen bond.
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