Synlett 2006(1): 0041-0044  
DOI: 10.1055/s-2005-922757
LETTER
© Georg Thieme Verlag Stuttgart · New York

Reversal of Enantioselectivity by Catalyst Protonation: Asymmetric ­Hydrocyanation of Imines with Oxazaborolidines

Albrecht Berkessel*, Santanu Mukherjee, Johann Lex
Institut für Organische Chemie der Universität zu Köln, Greinstrasse 4, 50939 Köln, Germany
Fax: +49(221)4705102; e-Mail: berkessel@uni-koeln.de;
Further Information

Publication History

Received 29 September 2005
Publication Date:
16 December 2005 (online)

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Abstract

A new application of chiral oxazaborolidines in asymmetric transformation, namely the hydrocyanation of imines, is described. The effect of protonation of these catalysts on the reactivity and enantioselectivity of hydrocyanations is studied. Significant increase in reaction rate is observed upon protonation of the catalysts, along with the reversal of the sense of stereoinduction.