New Highly Asymmetric Henry Reaction Catalyzed by CuII and aC1-Symmetric Aminopyridine Ligand, and Its Application to the Synthesis of Miconazole
作者:Gonzalo Blay、Luis R. Domingo、Victor Hernández-Olmos、José R. Pedro
DOI:10.1002/chem.200800069
日期:2008.5.19
A new catalytic asymmetricHenryreaction has been developed that uses a C(1)-symmetric chiral aminopyridineligand derived from camphor and picolylamine. A variety of aromatic, heteroaromatic, aliphatic, and unsaturated aldehydes react with nitromethane and other nitroalkanes in the presence of DIPEA (1.0 equiv), Cu(OAc)(2)*H(2)O (5 mol %), and an aminopyridineligand (5 mol %) to give the expected
Synthesis of <i>C</i><sub>1</sub>-Symmetric Chiral Secondary Diamines and Their Applications in the Asymmetric Copper(II)-Catalyzed Henry (Nitroaldol) Reactions
作者:Yirong Zhou、Junfang Dong、Fanglin Zhang、Yuefa Gong
DOI:10.1021/jo102124d
日期:2011.1.21
A small library of C1-symmetric chiral diamines (L1−L9) was constructed via condensing exo-(−)-bornylamine or (+)-(1S,2S,5R)-menthylamine with various Cbz-protected amino acids. Among them, ligand L1/CuCl2·2H2O complex (2.5 mol %) shows outstanding catalytic efficiency for Henryreaction between a variety of aldehydes and nitroalkanes to afford the expected products in high yields (up to 98%) with
New chiral thiols and C2-symmetrical disulfides of Cinchona alkaloids: ligands for the asymmetric Henry reaction catalyzed by CuII complexes
作者:Mariola Zielińska-Błajet、Jacek Skarżewski
DOI:10.1016/j.tetasy.2009.07.020
日期:2009.9
Seven Cinchona alkaloids were reacted with thioacetic acid and Bu3P/diethyl diazadicarboxylate in THF at 0-25 degrees C to give the corresponding thiolacetates with complete inversion of configuration at the substitution center. The thus obtained chiral thiolesters were converted into thiols and these compounds were oxidized to the respective disulfides of C-2-symmetry. Both C-9 thioles and disulfides were tested as chiral ligands in the Cu-catalyzed asymmetric Henry reaction. When the thiol derivatives of an 8,9-like configuration were applied in the reaction of benzaldehyde and nitromethane, the obtained nitroaldol was of the same absolute configuration as the catalyst and the observed enantioselectivity was up to 83% ee. These ligands gave higher ees than the corresponding thioethers, disulfides, and thioles of 8,9-unlike configuration. The results obtained are in agreement with the proposed transition-state model involving nucleophilic attack of a deprotonated nitromethane directed preferably at one side of the O-complexed benzaldehyde. (C) 2009 Elsevier Ltd. All rights reserved.
Asymmetric nitroaldol reaction catalyzed by copper–diamine complexes: selective construction of two contiguous stereogenic centers
作者:Rafał Kowalczyk、Jacek Skarżewski
DOI:10.1016/j.tetasy.2009.10.001
日期:2009.11
Chiral copper(II) complexes of secondary bisamines derived from 1,2-diaminocyclohexane were successfully used in the diastereoselective nitroaldol reaction. The reactions were carried out in the presence of 10 mol % of the Cu(II) complex and 7.7 mol % of i-Pr2NEt in 2-propanol at -30 degrees C. Good to excellent yields, enantioselectivities of up to 99%, and moderate to excellent diastereoselectivities were obtained for both aromatic or aliphatic aldehydes and various prochiral nitrocompounds forming the corresponding beta-nitroalcohols with two contiguous stereocenters. (C) 2009 Elsevier Ltd. All rights reserved.