Synthesis of phthalimides
An efficient and simple method enables the N-alkylation of aromatic cyclic imides using cesium carbonate as the base in anhydrous N,N-dimethylformamide at low temperatures (20-70˚C). The employment of microwave irradiation presents noteworthy advantages over conventional heating. The method is compatible with base labile functional groups.
M. I. Escudero, L. D. Kremenchuzky, I. A. Perillo, H. Cerecetto, M. M. Blanco, Synthesis, 2011, 571-576.
Transition-metal-free multicomponent reactions involving arynes, isocyanides, and CO2 as the third component resulted in the formation of N-substituted phthalimides in good yields, whereas the use of water as the third component furnished benzamide derivatives in good yields. These reactions took place under mild conditions with broad scope.
T. Kaicharla, M. Thangaraj, A. T. Biju, Org. Lett., 2014, 16, 1728-1731.
In a palladium-catalyzed oxidative carbonylation reaction for the synthesis of phthalimides, an imine and H2O, which are generated in situ from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available materials with high atom- and step-economy in a one-pot manner.
F. Ji, J. Li, X. Li, W. Guo, W. Wu, H. Jiang, J. Org. Chem., 2018, 83, 104-112.
L-proline catalyzes a reaction between α,β-unsaturated aldehydes and maleimides to provide biologically and pharmaceutically important phthalimides. The reaction involves an efficient benzannulation that proceeds via a formal [4 + 2] cycloaddition of azadiene intermediates generated in situ from enals and N-substituted maleimides.
M. S. Akhthar, Y. R. Lee, J. Org. Chem., 2020, 85, 15129-15138.