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2005
Enantioselective syntheses
O 0031
Chiral Bis(amino alcohol)oxalamides as Ligands for Asymmetric Catalysis.
Catalyzed Enantioselective Addition of Diethylzinc to Aldehydes. —
31- 033 Ti(IV)
Among 7 title ligands, hexaphenyl derivative OXA gives the best enantioselectivity in
the test reaction performed with benzaldehyde. By use of this ligand in the addition
reaction of several aromatic or aliphatic aldehydes in the presence of Ti(O-iPr)4, better
enantioselectivities are obtained with aliphatic aldehydes than with aromatic ones.
Only those aromatic aldehydes bearing substituents with weak electronic character at
the phenyl ring give satisfactory yields and e.e. values. The ligand also catalyzes the
reaction in the absence of Ti(O-iPr)4, although the alcohols are formed with opposite
configuration and in lower yields and enantioselectivities. — (BLAY, G.;
FERNANDEZ, I.; MARCO-ALEIXANDRE, A.; PEDRO*, J. R.; Tetrahedron:
Asymmetry 16 (2005) 6, 1207-1213; Dep. Quim. Org., Univ. Valencia, E-46100
Burjassot, Valencia, Spain; Eng.) — Klein
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