0000000000522734
AUTHOR
Christine Hoben
Investigation of Diketopiperazines Containing a Guanidino-Functionalized Sidechain as Potential Catalysts of Enantioselective Strecker Reactions
Diketopiperazine 1 consisting of L-(γ-guanidino-α-amino)butyric acid and L-phenylalanine was synthesized as the hydroacetate and as the hydronitrate. Its structure was confirmed by X-ray analysis. In contrast to reports in the literature (Lipton et al.), compound 1 does not induce enantioselevtive catalysis of Strecker reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Enantioselective Organocatalysis of Strecker and Mannich Reactions Based on Carbohydrates.
Efficient organocatalysts for enantioselective Strecker and Mannich reactions were constructed from glucosamine as a readily accessible chiral scaffold. A variety of aromatic aldimines were subjected to hydrocyanation with good to excellent yield (72–98 %) and, in part, high enantioselectivity (69–95 % ee). Influence of the catalyst architecture on the enantioselectivity obviously arises from restrictions imposed on the conformational flexibility of the monosaccharidic backbone. In the asymmetric Mannich reaction moderate yields (up to 76 %) and enantioselectivities (up to 58 % ee) have been achieved with the described catalyst.