Zwitterion-Catalyzed Isomerization of Maleic to Fumaric Acid Diesters

Fumaric acid diesters are important building blocks for organic synthesis. A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair were found to be effective in catalyzing the isomerization of maleic acid diesters to give fumaric acid diesters. Comparison of the performance of different zwitterionic organocatalysts toward the reaction revealed that nonclassical hydrogen bonding was involved in the stabilization of the Michael adduct intermediate.

Automated summary

Fumaric acid diesters are essential building blocks in organic synthesis, and zwitterionic organocatalysts based on an amide anion/iminium cation charge pair have been found to effectively catalyze the isomerization of maleic acid diesters to produce fumaric acid diesters. Comparative studies on different zwitterionic organocatalysts revealed that nonclassical hydrogen bonding plays a crucial role in stabilizing the Michael adduct intermediate.