Asymmetric synthesis using catalysts containing multiple stereogenic centres and a trans-1,2-diaminocyclohexane core; reversal of predominant enantioselectivity upon N-alkylation

N-Methylation of ligands containing a trans-1,2-diaminocyclohexane core and multiple stereogenic centres is shown to provide the product of the opposite configuration in significant enantiomeric excess, in the addition of diethylzinc to aldehydes. Some of the ligands were effective in an asymmetric Michael addition. (C) 2004 Elsevier Ltd. All rights reserved.