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1.
The main objective of this study is to develop readily accessible and recyclable solid catalysts for enantioselective reactions. To achieve this, magnetic MCM-41 and non-magnetic SBA-15 mesoporous supports were prepared, then mesoporous silica supported chiral urea-amine bifunctional catalysts were synthesized by grafting of chiral urea-amine ligand onto SBA-15 and magnetic MCM-41. The magnetic and non-magnetic supports and so-prepared solid catalysts were characterized by using different methods such as N2 sorption measurements, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope-energy dispersive X-ray analysis (FESEM-EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Results showed that (1R, 2R) or (1S, 2S)-1,2-diphenylethane-1,2-diamine was successively immobilized onto magnetic MCM-41 and SBA-15 pores. The heterogeneous chiral solid catalysts and their homogenous counterparts exhibited high activities both enantioselective transfer hydrogenation reaction (up to 99% conversion and 65% ee) and enantioselective Michael reaction (up to 98% conversion and 26% ee). Moreover, the SBA-15 supported solid catalysts were separated from the reaction mixture by simple filtration, whereas the magnetic MCM-41 supported solid catalysts were separated by simple magnetic decantation and reused in three consecutive catalytic experiments. 相似文献
2.
Angel Avila Rafael Chinchilla Enrique Gómez-Bengoa Carmen Nájera 《Tetrahedron: Asymmetry》2013,24(23):1531-1535
Simple and commercially available chiral 1,2-diamines were used as organocatalysts for the enantioselective conjugate addition of aldehydes, including α,α-disubstituted, to maleimides. The reaction was carried out in the presence of hexanedioic acid as an additive in aqueous solvents at room temperature. By employing (1S,2S)- and (1R,2R)-cyclohexane-1,2-diamine as organocatalysts, the corresponding Michael adducts bearing new stereocenters were obtained in high or quantitative yields with enantioselectivities of up to 92%, whereas the use of (1S,2S)-1,2-diphenylethane-1,2-diamine gave a much lower ee. Theoretical calculations were used to justify the observed sense of the stereoinduction. 相似文献
3.
Abstract The direct asymmetric aldol reaction catalyzed by the simple and commercially available chiral primary diamines, (1S,2S)-1,2-diphenylethane-1,2-diamine and (1R,2R)-1,2-diphenylethane-1,2-diamine, is presented. The catalyst system is a primary amine with Br?nsted acid–catalyzed direct aldol reaction of p-nitrobenzaldehyde and cyclohexanone with high chemo- and stereoselectivity on water, which furnishes the corresponding β-hydroxyketone with up to 94% ee. 相似文献
4.
A. E. Sibiryakova A. N. Reznikov V. B. Rybakov Yu. N. Klimochkin 《Russian Journal of General Chemistry》2016,86(11):2477-2483
Chiral ligands—derivatives of (1R,2R)-cyclohexane-1,2-diamine, (1R,2R)-diphenylethane-1,2-diamine, and (2S,3S)-bicyclo[2.2.2]octane-2,3-diamine—and octahedral Ni(II) complexes on their basis have been synthesized. 相似文献
5.
New primary amine-guanidines derived from the monoguanylation of (1S,2S)- and (1R,2R)-cyclohexane-1,2-diamine have been prepared and used as chiral organocatalysts for the enantioselective conjugate addition of α,α-disubstituted aldehydes to maleimides. The corresponding Michael adducts bearing a new stereocenter were generally obtained in high or quantitative yields and with good enantioselectivities (up to 93% ee). 相似文献
6.
Lu Liu Mingde Ye Xingen Hu Xiaochun Yu Lixue Zhang Xinxiang Lei 《Tetrahedron: Asymmetry》2011,22(16-17):1667-1671
A series of chiral salen C2-symmetric aminophenols 1–4, which were derived from (1R,2R)- or (1S,2S)-1,2-diphenylethane-1,2-diamine with the corresponding salicylic aldehyde through a [2+2] condensation reaction, have been prepared. The NMR studies demonstrated that they can function as chiral solvating agents for the determination of the enantiomeric purity of chiral carboxylic acids. 相似文献
7.
Yu. S. Kudyakova M. V. Goryaeva Ya. V. Burgart V. I. Saloutin 《Russian Journal of Organic Chemistry》2011,47(3):331-339
Ethyl 2-ethoxymethylidene-3-oxo-3-polyfluoroalkylpropionates reacted with (1S,2S)-1,2-diphenylethane-1,2-diamine to give diethyl 2,2′-{[(1S,2S)-diphenylethane-1,2-diyl]bis[iminomethylidene]}bis(3-oxo-3-polyfluoroalkyl)alkanoates which were used as ligands to obtain chiral complexes with transition metals. 相似文献
8.
Pingli Lv Rongxiu Zhu Tongxiang Lu Steven E. Wheeler Dongju Zhang Ruoxi Wang Chengbu Liu 《Tetrahedron: Asymmetry》2013,24(24):1598-1604
Computational studies to determine the origin of enantioselectivity in the (1R,2R)-1,2-diphenylethane-1,2-diamine (DEPN)–Brønsted acid catalyzed epoxidation of 2-cyclohexen-1-one have been performed using density functional theory. Transition states for conjugate addition and ring closure steps of the epoxidations catalyzed by three different catalyst systems were characterized. Our calculations show that the Csp2H?O H-bond interaction between the benzene ring of the catalyst and H2O is mainly responsible for the chiral discrimination observed. The Brønsted acid counterion plays a very important role in ensuring high enantioselectivity by improving the rigidity of the transition state structures to allow the efficient formation of the Csp2H?O H-bond. Moreover, we explain why these two diamine catalysts (1S,2S)-DACH and (1R,2R)-DPEN display consistent enantioselectivities in the catalytic epoxidation of 2-cyclohexen-1-one when combining with three different cocatalysts; achiral TFA, and chiral (R)- and (S)-TRIP. 相似文献
9.
《Tetrahedron: Asymmetry》2000,11(3):773-779
Chiral C2-symmetric diphenylthiophosphoramides 1 and 2 were prepared in high yields from the reaction of diphenylthiophosphinic chloride with (1R,2R)-(−)-1,2-diaminocyclohexane and (1R,2R)-(+)-1,2-diphenylethylenediamine, respectively. Another novel chiral ligand 4 was prepared from reaction of diphenylthiophosphinic chloride with (R)-(+)-1,1′-binaphthyl-2,2′-diamine using butyllithium as a base. They were used as catalytic chiral ligands in the silver(I)-promoted enantioselective allylation reaction of aldehydes with allyltributyltin. 相似文献
10.
《Tetrahedron: Asymmetry》2000,11(3):835-841
Chiral C2-symmetric diphenylselenophosphoramides 1 and 2 were prepared from the reaction of diphenylselenophosphinic chloride with (1R,2R)-(−)-1,2-diaminocyclohexane and (1R,2R)-(+)-1,2-diphenylethylenediamine, respectively, in high yields. Another novel chiral ligand 3 was prepared from the reaction of diphenylselenophosphinic chloride with (R)-(+)-1,1′-binaphthyl-2,2′-diamine using butyllithium as the base. The ligands were used as catalytic chiral ligands in the titanium(IV) alkoxide-promoted enantioselective addition reaction of diethylzinc to aldehydes. 相似文献
11.
We have proven that primary amine/thiophosphinamide incorporating (1R,2R)-1,2-diphenylethane-1,2-diamine is an efficient catalyst for the asymmetric Michael addition of acetone to (E)-2-azido β-nitrostyrenes. Under the optimal reaction conditions, the corresponding Michael addition products were obtained in excellent yields with almost perfect stereocontrol. Upon treatment with Et3SiH/InCl3, the Michael addition products could be successfully converted to the related 2-methyltetrahydroquinolines in acceptable yields with moderate to excellent diastereoselectivity and without appreciable loss in optical purity. This process provides a highly enantioselective pathway for the synthesis of biologically important 2-methyltetrahydroquinoline derivatives. 相似文献
12.
《Tetrahedron: Asymmetry》2000,11(20):4105-4111
The efficient preparation of enantiomerically pure (R)- and (S)-2-bromohexadecanoic acids with e.e.>95% through resolution with the use of a recoverable chiral auxiliary is described. The procedure involves three reactions: Steglich esterification, DIBAL reduction, and Sharpless oxidation. The assessment of the enantiomeric purity is based on NMR analysis by using (1R,2R)-(+)-diphenylethane-1,2-diamine as a chiral solvating agent. 相似文献
13.
Patrizia Scafato Stefania Labano Giovanni Cunsolo Carlo Rosini 《Tetrahedron: Asymmetry》2003,14(24):3873-3877
New diastereoisomeric phosphites based on either (R)- or (S)-2,2′-dihydroxy-1,1′-binaphthyl (BINOL) and having the chiral alcoholic moiety derived from the monobenzyl ether of (R,R)-1,2-diphenylethane-1,2-diol have been prepared and used as chiral ligands in the enantioselective copper-catalyzed 1,4-addition of diethylzinc to chalcone and 2-cyclohexen-1-one (enantiomeric excesses up to 48%). With the (aR,R,R) ligand dimethylzinc adds enantioselectively to (E)-cyclopentadecen-2-en-1-one to give (R)-(−)-muscone (68% yield, 78% ee). This provides an efficient access to a valuable ingredient of the perfume industry. However, with the (aS,R,R) ligand, (S)-(+)-muscone is obtained with longer reaction times (37% yield and 10% ee) with a very high double diastereoselection effect being observed. 相似文献
14.
Guohua Liu Mouming Liu Yunqiang Sun Jianyao Wang Chuanshou Sun Hexing Li 《Tetrahedron: Asymmetry》2009,20(2):240-246
Two mesoporous silica-supported chiral Rh and Ru catalysts 5 and 6 with ordered two-dimensional hexagonal mesostructures were prepared by directly postgrafting organometallic complexes RhCl[(R)-MonoPhos(CH2)3Si(OMe)3][(R,R)-DPEN] and RuCl2[(R)-MonoPhos(CH2)3Si(OMe)3][(R,R)-DPEN] (DPEN = 1,2-diphenylethylenediamine) on SBA-15. During the asymmetric hydrogenation of various aromatic ketones under 40 atm H2, both catalysts exhibited high catalytic activities (more than 97% conversions) and moderate enantioselectivities (33–54% ee). Furthermore, the chiral Rh catalyst 5 could be easily recovered and used repetitively five times without significantly affecting its catalytic activity and enantioselectivity. A catalytic comparison of the mesoporous silica-supported chiral Rh catalyst 4 prepared by a postmodification method is also discussed. 相似文献
15.
[reaction: see text] Chiral Ru-TsDPEN [N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine]-derived catalysts were first successfully immobilized onto amorphous silica gel and mesoporous silicas of MCM-41 and SBA-15 by an easily accessible approach. The catalyst immobilized on silica gel demonstrated remarkably high catalytic activities and excellent enantioselectivities (up to >99% ee) for the heterogeneous asymmetric transfer hydrogenation of various ketones. Particularly, the catalyst could be readily recovered and reused in multiple consecutive catalytic runs (up to 10 uses) with the completely maintained enantioselectivity. 相似文献
16.
17.
Naoki Haraguchi Akihiro Nishiyama Shinichi Itsuno 《Journal of polymer science. Part A, Polymer chemistry》2010,48(15):3340-3349
Monodisperse, crosslinked poly(divinylbenzene) and poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) microspheres with (1R,2R)‐N1‐toluenesulfonyl‐1,2‐diphenylethylene‐1,2‐diamine ((R,R)‐TsDPEN) moiety were successfully prepared by precipitation polymerization. Introduction site of the (R,R)‐TsDPEN moiety into the polymer microspheres could be controlled by changing the order of addition of the corresponding monomers. The functionalized polymer microspheres were applied to asymmetric transfer hydrogenation of ketone and imine. Polymer microsphere‐supported chiral catalysts showed good reactivity and enantioselectivity in the catalytic asymmetric transfer hydrogenations. Chiral secondary alcohol was quantitatively obtained with 94% ee in the asymmetric transfer hydrogenation of acetophenone in water. We also found that introduction site of the chiral catalyst and hydrophobicity of the microspheres, as well as degree of the crosslinking, affected the yield and enantioselectivity of chiral product in this reaction. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3340–3349, 2010 相似文献
18.
《中国化学快报》2022,33(3):1459-1462
Two pairs of Pt(II) enantiomers ((RR)/(SS)-PyPt, ((RR)/(SS)-Py: N,N'-(1,2-diphenylethane-1,2-diyl)dipicolinamide; (RR)-P/M-QPt, ((RR)/(SS)-Q: N,N'-((1R,2R)-1,2-diphenylethane-1,2-diyl)bis(quinoline-2-carboxamide)) were synthesized, respectively, with good circularly polarized luminescence (CPL) and tunable dissymmetry factors (g) by molecular self-induction with (RR)/(SS)-1,2-diphenylethane-1,2-diamine as carbon chiral sources. In the (RR)-P-QPt and (SS)-M-QPt, specific P- and M-configurations were effectively induced from intrinsic chiral carbon centres (R or S), ingeniously avoiding the racemic mixture formation and chiral separation. Furthermore, the chirality originating from both chiral carbon centres and helicene-like structure improves the g factor significantly, which provides a new molecular design strategy for chiral Pt(II) enantiomers with good CPL properties. 相似文献
19.
ChaoFen Yang HeYan Jiang Jian Feng HaiYan Fu RuiXiang Li Hua Chen XianJun Li 《Journal of molecular catalysis. A, Chemical》2009,300(1-2):98-102
A series of silica (SiO2) supported iridium catalysts stabilized by cinchona alkaloids was prepared and applied in the heterogeneous asymmetric hydrogenation of acetophenone. Cinchona alkaloids exhibited a marked ability to stabilize and disperse the Ir particles. In the presence of (1S,2S)-diphenylethylenediamine ((1S,2S)-DPEN)) as chiral modifier, the cinchonidine (CD) stabilized catalyst 5%Ir/2CD-SiO2 exhibited excellent catalytic performance in the asymmetric hydrogenation of acetophenone in MeOH. Under the optimum conditions, the ee value of (R)-phenylethanol achieved 79.8% and no other product was produced, a higher enantioselectivity than that reported up to now for acetophenone hydrogenation catalyzed by the supported metal catalysts modified by chiral reagents. In particular, a synergistic effect between (1S,2S)-DPEN and CD was observed, which significantly accelerated the reaction rate and enhanced the enantioselectivity. The catalyst can be reused several times without a significant loss of activity and enantioselectivity. 相似文献
20.
Ketang Liu Ronghua Jin Tanyu Cheng Xiangming Xu Fei Gao Prof. Guohua Liu Prof. Hexing Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(48):15546-15553
A functionalized periodic mesoporous organosilica with incorporated chiral bis(cyclohexyldiamine)‐based NiII complexes within the silica framework was developed by the co‐condensation of (1R,2R)‐cyclohexyldiamine‐derived silane and ethylene‐bridge silane, followed by the complexation of NiBr2 in the presence of (1R,2R)‐N,N′‐dibenzylcyclohexyldiamine. Structural characterization by XRD, nitrogen sorption, and TEM disclosed its orderly mesostructure, and FTIR and solid‐state NMR spectroscopy demonstrated the incorporation of well‐defined single‐site bis(cyclohexyldiamine)‐based NiII active centers within periodic mesoporous organosilica. As a chiral heterogeneous catalyst, this functionalized periodic mesoporous organosilica showed high catalytic activity and excellent enantioselectivity in the asymmetric Michael addition of 1,3‐dicarbonyl compounds to nitroalkenes, comparable to those with homogeneous catalysts. In particular, this heterogeneous catalyst could be recovered easily and reused repeatedly up to nine times without obviously affecting its enantioselectivity, thus showing good potential for industrial applications. 相似文献