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

The conjugate enantioselective addition of aldehydes, mainly alpha,alpha-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. (C) 2016 Elsevier Ltd. All rights reserved.