Enantioselective organocatalysis in ionic liquids: Addition of aliphatic aldehydes and ketones to diethyl azodicarboxylate

The enantioselective addition of aldehydes to diethyl azodicarboxylate in ionic liquids in the presence of chiral organocatalysts has been investigated. Of seven different organocatalysts tested, L-prohne and L-thiazohne-2-carboxylic acid gave the highest enantioselectivities (up to 94 % ee). The best results were obtained by using [bmim]PF6 and [hmim]BF4 as ionic liquids. The scope of the methodology was probed by using various aldehydes and ketones. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).