Synthesis 2006(21): 3727-3738  
DOI: 10.1055/s-2006-950237
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Highly Substituted Unsymmetrical 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes by Aldimine Cross-Coupling

Coralie Kison, Till Opatz*
Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
Fax: +49(6131)3924786; e-Mail: opatz@uni-mainz.de;
Further Information

Publication History

Received 19 May 2006
Publication Date:
09 October 2006 (online)

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Abstract

α-Aminonitriles derived from aromatic aldehydes and primary amines can be deprotonated quantitatively without the use of protecting groups. The 1,2-addition of the resulting stabilized α-aminocarbanions to imines yields α-aminoimines and the tautomeric enediamines. These unstable compounds can directly be oxidized to 1,2-diimines or reduced to 1,2-diamines in a one-pot reaction. 1,2-Diamines can be obtained in high diastereoselectivity by reduction of the 1,2-diimines. In this case, the relative configuration of the products can be chosen depending on the reduction conditions. Cyclization of the unsymmetrical diimines with halomethyl ethers or esters leads to 1,3,4,5-tetrasubstituted imidazolium salts which can serve as starting materials for the preparation of highly substituted nucleophilic carbenes.