Organocatalytic enantioselective conjugate addition of aldehydes to maleimides in deep eutectic solvents

The conjugate enantioselective addition of aldehydes, mainly α,α-disubstituted, to maleimides leading to enantioenriched succinimides, has been achieved in recyclable deep eutectic solvents at room temperature. Enantiomerically pure carbamate-monoprotected trans-cyclohexane-1,2-diamines are used as organocatalysts, affording high yields and up to 94% ee of the final succinimides. The product can be extracted from the deep eutectic solvent, which retains the chiral organocatalyst, allowing both the solvent and catalyst to be reused.We thank the financial support from the Spanish Ministerio de Economía y Competitividad (project CTQ2015-66624-P) and the University of Alicante (VIGROB-173 and UAUSTI14). J. F.-F. particularly acknowledges the Vicerrectorado de Investigación y Transferencia de Conocimiento of the University of Alicante for a fellowship