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Free keywords:
amino alcohols; aziridines; carboxylic acids; organocatalysis; self-assembly
Abstract:
Organocatalysis, catalysis using small organic molecules, has recently evolved into a general approach for asymmetric synthesis, complementing both metal catalysis and biocatalysis.[1] Its success relies to a large extent upon the introduction of novel and generic activation modes.[2] Remarkably though, while carboxylic acids have been used as catalyst directing groups in supramolecular transition-metal catalysis,[3] a general and well-defined activation mode for this useful and abundant substance class is still lacking. Herein we propose the heterodimeric association of carboxylic acids with chiral phosphoric acid catalysts as a new activation principle for organocatalysis. This self-assembly increases both the acidity of the phosphoric acid catalyst and the reactivity of the carboxylic acid. To illustrate this principle, we apply our concept in a general and highly enantioselective catalytic aziridine-opening reaction with carboxylic acids as nucleophiles.
