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Copper‐Catalyzed Asymmetric Conjugate Addition of Trialkylaluminium Reagents to Trisubstituted Enones: Construction of Chiral Quaternary Centers
Author(s) -
Vuagnouxd'Augustin Magali,
Alexakis Alexandre
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701001
Subject(s) - conjugate , reagent , catalysis , quaternary , copper , combinatorial chemistry , chemistry , mathematics , organic chemistry , geology , paleontology , mathematical analysis
Me 3 Al, Et 3 Al, 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(CH 3 CN) 4 ]BF 4 or [CuOTf] 2 ⋅C 6 H 6 ) 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.