234. M. Vuagnoux-d'Augustin, A. Alexakis,
     “Copper catalysed asymmetric conjugate addition of trialkylaluminuim reaggents to trisubstituted enones: construction of chiral quaternary centers”
     Chem. Eur. J. 2007, 13, 9647-9662.

Me₃Al, Et₃Al, and vinylalane species undergo enantioselective conjugate addition to a wide range of 2- or 3-substituted enones (cyclopent-2-enones, cyclohex-2-enones, 3-methyl cyclohept-2-enone) in the presence of catalytic amount of copper salt (copper thiophene carboxylate, [Cu(CH₃CN)₄]BF₄ or [CuOTf]₂⋅C₆H₆) and tropos-phosphoramidite-based ligand. Thus, chiral quaternary centers can be built, with up to 98 % ee after rigorous optimization of experimental conditions. It was shown that the main important parameter was the order of the introduction of the reagents. Then, the generated enantioenriched aluminium enolates and the chiral conjugate adducts were functionalized and used for subsequent reactions.

DOI : 10.1002/chem.200701001 

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