A catalytic enantioselective route to cis- and trans-3,4,4,5-tetrasubstituted cyclohexanones; remarkable chiral catalyst control in sequential catalytic 1,4-additions to cyclohexadienones

Asymmetric copper-phosphoramidite catalysed conjugate addition of Et2Zn to easily accessible, nearly enantiomerically pure cyclohexenones 2 and 4 was performed. Depending on the enantiomer of the chiral phosphoramidite used, the cis- or trans-3,4,4,5-tetrasubstituted cyclohexanones 5 and 6 could be formed selectively. Surprisingly, there is no directing effect of the 5-eth yl- or 4-alkoxy-substituents and the stereochemical outcome is only governe d by the configuration of the chiral ligand. (C) 2001 Published by Elsevier Science Ltd.