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Asymmetric Intramolecular Crossed-Benzoin Reactions by N-Heterocyclic Carbene Catalysis

Dieter Enders*, Oliver Niemeier, Tim Balensiefer

*Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany, Email:

D. Enders, O. Niemeier, T. Balensiefer, Angew. Chem. Int. Ed., 2006, 45, 1463-1467.

DOI: 10.1002/anie.200503885


An enantioselective intramolecular crossed-benzoin reaction catalyzed by novel chiral N-heterocyclic carbenes has been developed. A tetracyclic trazolium salt catalyzes the cyclization with generation of a quartenary stereocenter in high yields and excellent enantomeric excess.

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Key Words

benzoins, asymmetric synthesis, benzoin reaction, heterocycles, homogeneous catalysis, organocatalysis, N-heterocyclic carbenes

ID: J06-Y2006-500