Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acids and ‐amino alcohol‐based chiral ligand (2R)‐N‐[(1R,2S)‐1‐hydroxy‐1‐phenylpropan‐2‐yl]‐3‐phenyl‐2‐(tosylamino) propanamide (1f) without using titanium complex. The catalytic system employing 15 mol% of 1f was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes
Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acid amide chiral ligand (2S)‐3‐phenyl‐N‐((R)‐1‐phenyl‐ethyl)‐2‐(tosylamino)propanamide without using titanium complex. The catalytic system employing 10 mol% of 1g was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron‐donating and electron‐withdrawing
Abstract Enantioselectiveaddition of diethylzinc (ZnEt2) to a series of aromatic aldehydes was promoted using a modular prolinol chiral ligand, 2-(S)-2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)-4-nitrophenol (1a), without using titanium complex. The catalytic system employing 15 mol% of 1a was found to promote the addition of diethylzinc to a wide range of aromatic aldehydes with electron-donating
A series of chiral oxazolidines derived from (1R, 2S)-cis-1-amino-2-indanol was found to be effective in
promoting the asymmetric addition of diethylzinc to aldehydes. Among the ligands developed, it was found that ligand 1b
in the presence of Ti(OiPr)4 yielded the highest enantioselectivities when it was applied in the catalytic asymmetric addition
of diethylzinc to aldehydes (up to 91% ee).
Enantioselective addition of diethylzinc to aromatic aldehydes catalyzed by Ti(IV) complexes of C2-symmetrical chiral BINOL derivatives
作者:Shaohua Gou、Zaher M.A. Judeh
DOI:10.1016/j.tetlet.2008.10.149
日期:2009.1
Enantioselective addition of diethylzinc to a series of aromatic aldehydes is developed using new chiral C2-symmetric ligand (S)-2,2'-(1,1'-binaphthyl-2,2'-diylbis(oxy))bis(methylene)bis(4-nitrophenol) (S)-2b. The catalytic system employing 10 mol % of (S)-2b and 120 mot %. of Ti(OiPr)(4) was found to promote the addition of diethylzinc to a wide range of aromatic aldehydes with electron-donating and electron-withdrawing substituents, giving up to 89% ee and up to 95% yield of the corresponding secondary alcohol under mild conditions. (C) 2008 Elsevier Ltd. All rights reserved.