Pergamon Tetrahedron: Asymmetry 10 (1999) 1019–1023 Synthesis of non-racemic nitrogen-containing diselenides as efficient precursor catalysts in the diethylzinc addition to benzaldehyde Claudio Santi a and Thomas Wirth b,* a Istituto di Chimica Organica Università degli Studi, I-06123 Perugia, Italy b Institut für Organische Chemie der Universität Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland Received 23 February 1999; accepted 10 March 1999 Abstract Short synthetic procedures for the preparation of new chiral, non-racemic nitrogen-containing diselenides are described. Only 1 mol% of these diselenides can very efficiently catalyze the diethylzinc addition to benzaldehydes affording the secondary alcohols in high enantiomeric purities (up to 97% ee). © 1999 Elsevier Science Ltd. All rights reserved. The enantioselective addition of dialkylzinc reagents to aldehydes can be catalyzed by a large variety of chiral compounds affording optically active secondary alcohols. 1 Detailed mechanistic studies have also been performed. 2 Diols, diamines and amino alcohols were found to be highly efficient catalysts for this reaction. Recently, it has been shown that both sulfur- 3 and selenium-containing 4 amines are also able to catalyze diethylzinc addition reactions. We observed a positive nonlinear relationship (asymmetric amplification) between the enantio- meric excesses of the catalyst generated from nitrogen-containing diselenides and the product. 4c This phenomenon 5 was subsequently also observed in the corresponding sulfur-containing compounds. 3e By NMR studies we demonstrated that the catalyst derived from 1 is aggregated and acts as a bidentate ligand. 4c In this paper we report on efficient and simple routes for the synthesis of new chiral non-racemic nitrogen-containing diselenides as procatalysts for diethylzinc addition to benzaldehyde. * Corresponding author. E-mail: wirth@ubaclu.unibas.ch 0957-4166/99/$ - see front matter © 1999 Elsevier Science Ltd. All rights reserved. PII: S0957-4166(99)00090-7