Organocatalysis in ionic liquids: Highly efficient L-proline-catalyzed direct asymmetric Mannich reactions involving ketone and aldehyde nucleophiles

摘要

Proline-catalyzed direct asymmetric Mannich reactions of N-PMP protected alpha-imino ethyl glyoxylate with various aldehydes and ketones in ionic liquids afforded both alpha- and beta-amino acid derivatives with excellent yields and enantioselectivities, providing facile product isolation, catalyst recycling, and significantly improved reaction rates, ca 4- to 50-fold. Three component Mannich reactions involving other imines also worked well in ionic liquids. Significant advantages and limitations of ionic liquid solvents in this reaction have been revealed. [References: 37]