No abstract

Readily available cinchona alkaloids have been used as organocatalysts in the highly efficient stereoselective hydroxyalkylation of heteroaromatics such as indoles with 3,3,3‐trifluoropyruvate (2, see scheme). High yields and ee values of both enantiomers of the products, depending on the catalyst used, indicate the usefulness of the developed methodology.

Einfach verfügbare China‐Alkaloide als Organokatalysatoren ermöglichten die hoch effiziente stereoselektive Hydroxyalkylierung von Heteroarenen wie den Indolen mit 3,3,3‐Trifluorpyruvat (siehe Schema). Hohe Ausbeuten und ee‐Werte beider Enantiomere der Produkte, je nach verwendetem Katalysator, belegen die Leistungsfähigkeit des Verfahrens.

Trifluoropyruvate. -The first highly enantioselective organocatalytic Friedel-Crafts hydroxyalkylation reaction of indoles with ethyl trifluoropyruvate is carried out with cinchona alkaloids. Highest yields and enantioselectivities for the (R)-isomers are achieved with cinchonine, while cinchonidine gives best results for the (S)-antipodes. -(TOEROEK*, B.; ABID, M.; LONDON, G.; ESQUIBEL, J.; TOEROEK, M.; MHADGUT, S. C.; YAN, P.; PRAKASH, G. K. S.; Angew. Chem., Int. Ed. 44 (2005) 20, 3086-3089; Dep. Chem., Mich. Technol. Univ., Houghton, MI 49931, USA; Eng.) -S. Adam 38-122