کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5228098 | 1383624 | 2008 | 8 صفحه PDF | دانلود رایگان |
A series of chiral tetraaza ligands were studied for the enantioselective addition of dialkylzinc to aldehydes. These bis(amino amide) ligands show high enantioselectivity in the addition of organozincs to aromatic aldehydes. Different structural elements on the ligands seem to play an important role in determining the observed enantioselectivity. Ligand 4b (N,Nâ²-bis(N-l-valinyl)-1,3-diaminopropane, with an aliphatic spacer with 3C atoms) catalyzed the addition of Et2Zn to benzaldehyde, 1-naphtaldehyde, 4-methoxybenzaldehyde, and 4-chlorobenzaldehyde to give the corresponding alcohol products with excellent conversions and selectivities and with enantioselectivities of 99, 97, 98, and 82%, respectively. DFT calculations provide an understanding of the mechanism of the enantioselection process.
Journal: Tetrahedron - Volume 64, Issue 41, 6 October 2008, Pages 9717-9724