- Chiral Chromium Salen@rGO as Multipurpose and Recyclable Heterogeneous Catalyst
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The first immobilization of a pyrene-tagged chromium salen complex through π-π noncovalent interactions on reduced graphene oxide (rGO) is described. A very robust supported catalytic system is obtained to promote asymmetric catalysis in repeated cycles, without loss of activity or enantioselectivity. This specific behavior was demonstrated in two different catalytic reactions (up to ten reuses) promoted by chromium salen complexes, the cyclohexene oxide ring-opening reaction and the hetero-Diels-Alder cycloaddition between various aldehydes and Danishefsky's diene. Furthermore, the chiral chromium salen@rGO has been found to be compatible with a multi-substrate type use, in which the structure of the substrate involved is modified each time the catalyst is reused.
- Abd El Sater, Mariam,Mellah, Mohamed,Dragoe, Diana,Kolodziej, Emilie,Jaber, Nada,Schulz, Emmanuelle
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supporting information
p. 9454 - 9460
(2021/05/26)
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- Catalytic asymmetric oxo-Diels-Alder reactions with chiral atropisomeric biphenyl diols
-
New chiral atropisomeric biphenyl diols 3, 4 and 6 containing additional peripheral chiral centers with different steric bulkiness and/or electronic properties were synthesized. The X-ray crystal structure of 3 shows the formation of a supramolecular stru
- Yeung, Chi-Tung,Chan, Wesley Ting Kwok,Lo, Wai-Sum,Law, Ga-Lai,Wong, Wing-Tak
-
supporting information
p. 955 - 962
(2019/06/08)
-
- Enantiopure (P)- and (M)-3,14-bis(o-hydroxyaryl)tetrahydrobenzo[5]helicenediols and their helicene analogues: Synthesis, amplified circularly polarized luminescence and catalytic activity in asymmetric hetero-Diels–Alder reactions
-
Three pairs of enantiopure (P)- and (M)-3,14-bis(o-hydroxyaryl)tetrahydrobenzo[5]helicenediols (ArOH-H[5]HOLs), and enantiomers (P)- and (M)-3,14-bis(o-hydroxyphenyl)benzo[5]helicene-diols (PhOH-[5]HOLs) were designed and synthesized. It was found that co
- Fang, Lei,Li, Meng,Lin, Wei-Bin,Chen, Chuan-Feng
-
p. 7164 - 7172
(2018/11/23)
-
- C3-Symmetric Boron Lewis Acid with a Cage-Shape for Chiral Molecular Recognition and Asymmetric Catalysis
-
Chiral Lewis acids play an important role in the precise construction of various types of chiral molecules. Here, a cage-shaped borate 2 was designed and synthesized as a chiral Lewis acid that possesses a unique C3-symmetric structure composed of three homochiral binaphthyl moieties. The highly symmetrical structure of 2 with homochirality was clearly elucidated by X-ray crystallographic analysis. The peculiar chiral environment of 2?THF exhibited chiral recognition of some simple amines and a sulfoxide. Moreover, the application of 2?THF to hetero-Diels–Alder reactions as a chiral Lewis-acid catalyst afforded the enantioselective products, which were obtained through an entropy-controlled pathway according to the analysis of the relationship between optical yield and reaction temperature. In particular, the robust chiral reaction field of 2?THF allowed the first example of an asymmetric hetero-Diels–Alder reaction with a simple diene despite the requirement of high temperature.
- Konishi, Akihito,Nakaoka, Koichi,Maruyama, Hikaru,Nakajima, Hideto,Eguchi, Tomohiro,Baba, Akio,Yasuda, Makoto
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supporting information
p. 1273 - 1277
(2017/02/05)
-
- A Cr(salen)-based metal-organic framework as a versatile catalyst for efficient asymmetric transformations
-
A porous Cr(salen)-MOF can serve as an efficient and effective heterogeneous catalyst for a series of important asymmetric transformations including the Nazarov cyclization, aminolysis reaction, and Diels-Alder and hetero Diels-Alder reactions, resulting
- Xia, Qingchun,Liu, Yan,Li, Zijian,Gong, Wei,Cui, Yong
-
supporting information
p. 13167 - 13170
(2016/11/09)
-
- A Family of Chiral Ferrocenyl Diols: Modular Synthesis, Solid-State Characterization, and Application in Asymmetric Organocatalysis
-
Readily available chiral diol scaffolds are useful as sources of chirality for asymmetric synthesis, however, few such scaffolds are readily available in enantiopure form. Reported herein is a cheap and modular synthesis of a novel family of chiral ferroc
- Nottingham, Chris,Müller-Bunz, Helge,Guiry, Patrick J.
-
supporting information
p. 11115 - 11119
(2016/10/13)
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- Silica-based helical rod supporting guanosine compounds catalyzed asymmetric hetero-Diels-Alder reaction
-
A series of silica-based helical rods were prepared and functionalized for immobilization of guanosine compounds in catalytic asymmetric hetero-Diels-Alder reaction. Nitrogen physisorption, electron microscopy and amino acid adsorption revealed that helic
- Li, Le,Zhang, Guangbin,Huang, Benhua,Ren, Lin,Zheng, Aqun,Zhang, Junjie,Sun, Yang
-
-
- Highly asymmetric hetero-Diels-Alder reaction using helical silica-supported Mn(III)-salen catalysts
-
Helical silica were prepared and functionalized by Mn(III)-salen complexes in order to catalyze asymmetric hetero-Diels-Alder reactions. Characterizations revealed doping of sodium lactate facilitated porosity, hydrolysis resistance and chiral configurati
- Li, Le,Li, Yu,Pang, Di,Liu, Fei,Zheng, Aqun,Zhang, Guangbin,Sun, Yang
-
p. 8096 - 8103
(2015/12/30)
-
- Trans-selective rhodium catalysed conjugate addition of organoboron reagents to dihydropyranones
-
The selective synthesis of 2,6-trans-tetrahydropyran derivatives employing the rhodium catalysed addition of organoboron reagents to dihydropyranone templates, derived from a zinc-catalysed hetero-Diels-Alder reaction, is reported. The addition of both arylboronic acids and potassium alkenyltrifluoroborates have been accomplished in high yields using commercially-available [Rh(cod)(OH)]2 catalyst. The selective formation of the 2,6-trans-tetrahydropyran stereoisomer is consistent with a mechanism involving alkene association and carbometalation on the less hindered face of the dihydropyranone.
- Edwards, Hannah J.,Goggins, Sean,Frost, Christopher G.
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p. 6153 - 6166
(2015/05/13)
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- Comparison of a molecular and an immobilized gadolinium(III)-tris[(1R,4S)- 3-heptafluorobutanoyl-camphor] as catalyst in the asymmetric Danishefsky-hetero-Diels-Alder-Reaction
-
On-column reaction gas chromatography combines the power of separation and rapid analysis of reactants and reaction products with screening of reactions in a single step. Not only conversions but the reaction rates at various temperatures can be obtained
- Stockinger, Skrollan,Trapp, Oliver
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p. 243 - 248
(2014/04/17)
-
- Planar-chiral bis-silanols and diols as h-bonding asymmetric organocatalysts
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The successful development of planar-chiral bis-silanols 3a-d and their application as asymmetric organocatalysts in hetero-Diels-Alder (HDA) reactions is described. All precursors were easily prepared by addition of commerically available silyl electrophiles to a dilithiated [2.2]paracyclophane derivative followed by silane oxidations. The analogous bis-carbinols 7a-c have been prepared by addition of suitable Grignard reagents to bis-methoxycarbonyl derivative 6. Both racemic as well as enantiopure planar-chiral bis-silanols and bis-carbinols were obtained in good yields. The catalytic activities of the bis-silanols were analyzed by monitoring HDA reactions between Rawal's diene and aldehydes by in situ IR spectroscopy and comparing the resulting data with those obtained in catalyses with the corresponding bis-carbinol derivatives. The results show for the first time that planar-chiral bis-silanols with hydrogen-bonding capabilities can be applied as asymmetric organocatalysts leading to enantiomerically enriched products. Enantiopure, planar-chiral [2.2]paracyclophane-based bis-silanols and their carbon diol analogs were synthesized and used as hydrogen-bond-donating organocatalysts in a hetero-Diels-Alder reaction with Rawal's diene.
- Beemelmanns, Christine,Husmann, Ralph,Whelligan, Daniel K.,Oezcubukcu, Salih,Bolm, Carsten
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supporting information; experimental part
p. 3373 - 3376
(2012/08/07)
-
- Synthesis and application of azolium ionic liquid tagged TADDOL catalysts
-
Ionic liquid (IL) tagged organocatalysts based on TADDOL (α, α, α′, α′-tetraaryl-2,2-dimethyl-1,3-dioxolane-4,5- dimethanol) comprising various aryl substituents tethered with triazolium and imidazolium based ionic liquids are synthesised in good yields.
- Yacob, Zekarias,Liebscher, Juergen
-
p. 312 - 319
(2013/09/24)
-
- cis-2,5-diaminobicyclo[2.2.2]octane, a new scaffold for asymmetric catalysis via salen-metal complexes
-
Chemical equations presented. A new C2 symmetric salen scaffold based on cis-2,5-diaminobicyclo[2.2.2]octane has been synthesized that forms complexes with a wide range of metals. The chromium(III) complex is shown to catalyze the hetero-Diels-
- White, James D.,Shaw, Subrata
-
supporting information; experimental part
p. 2488 - 2491
(2011/06/25)
-
- Evaluation of catalyst acidity and substrate electronic effects in a hydrogen bond-catalyzed enantioselective reaction
-
A modular catalyst structure was applied to evaluate the effects of catalyst acidity in a hydrogen bond-catalyzed hetero Diels-Alder reaction. Linear free energy relationships between catalyst acidity and both rate and enantioselectivity were observed, wh
- Jensen, Katrina H.,Sigman, Matthew S.
-
experimental part
p. 7194 - 7201
(2011/01/12)
-
- Oxo-Diels-Alder reaction of danishefskys diene with aldehydes, catalyzed by chiral tridentate chromium(III)-Schiff base complexes
-
The enantioselective hetero-Diels-Alder reaction of Danishefskys diene with simple aromatic and aliphatic aldehydes is catalyzed by chiral tridentate Schiff base-chromium(III) complexes. In many cases, 2,3-dihydropyran-4-ones are obtained in good yields (
- Miesowicz, Sawomir,Chaladaj, Wojciech,Jurczak, Janusz
-
scheme or table
p. 1421 - 1425
(2010/08/06)
-
- Enantioselective construction of cis-2,6-disubstituted dihydropyrans: Total synthesis of (-)-centrolobine
-
(Chemical Equation Presentation) This paper presents a simple and efficient route to chiral cis-6-substituted 2-(2-hydroxyethyl)-5,6-dihydro-2H-pyrans, a versatile chiral building block. The strategy is based on three key transformations: enantioselective
- Chaladaj, Wojciech,Kowalczyk, Rafa,Jurczak, Janusz
-
supporting information; experimental part
p. 1740 - 1743
(2010/05/18)
-
- Highly enantioselective hetero-Diels-Alder reactions between Rawal's diene and aldehydes catalyzed by chiral dirhodium(ii) carboxamidates
-
The first example of a chiral Lewis acid-catalyzed enantioselective hetero-Diels-Alder (HDA) reaction between 1-dimethylamino-3-silyloxy-1,3- butadiene (Rawal's diene) and aldehydes is described. The cycloaddition reaction under the influence of 1 mol% of
- Watanabe, Yudai,Washio, Takuya,Shimada, Naoyuki,Anada, Masahiro,Hashimoto, Shunichi
-
supporting information; experimental part
p. 7294 - 7296
(2010/06/13)
-
- Origin of the asymmetric induction in metallosalen-catalyzed reactions of aldehydes
-
This study investigates, experimentally and computationally, the role played by the structure of the diamine moiety of salen chromium complexes in determining the catalyst conformational equilibrium and, in consequence, the direction of asymmetric induction in metallosalen-catalyzed reactions of aldehydes. The Royal Society of Chemistry 2009.
- Chaiadaj, Wojciech,Jurczak, Janusz
-
supporting information; experimental part
p. 6747 - 6749
(2010/03/25)
-
- Chromium-thiophene-salen-based polymers for heterogeneous asymmetric hetero-Diels-Alder reactions
-
New chiral thiophene-salen ligands have been synthesized and the corresponding chromium complexes proved to be efficient catalysts for promoting asymmetric hetero-Diels-Alder reactions with good activities and high enantio-selectivities (up to 88% ee). Th
- Zulauf, Anais,Mellah, Mohamed,Guillot, Regis,Schulz, Emmanuelle
-
experimental part
p. 2118 - 2129
(2009/04/11)
-
- Asymmetric hetero Diels-Alder reaction catalyzed by chromium complexes of heterogeneously hybridized salen/salan ligands
-
Various heterogeneously or homogeneously hybridized salen/salan ligands were synthesized, and study of hetero Diels-Alder reactions using their chromium complexes as catalysts revealed that a well-designed heterogeneously hybridized ligand serves as a chi
- Eno, Satomi,Egami, Hiromichi,Uchida, Tatsuya,Katsuki, Tsutomu
-
p. 632 - 633
(2008/12/20)
-
- A novel chiral H′4-NOBIN schiff base for hetero-diels-alder reaction of danishefsky's diene with aldehydes
-
Novel chiral H′4-NOBIN was synthesized in 66% yield through partial hydrogenation of 2-amino-2′-hydroxy-1,1′-binaphthyl, and the structure was proved via X-ray analysis of its salicylaldehyde Schiff base, which was tested in the enantioselectiv
- Li, Xinsheng,Meng, Xiangyan,Su, Hong,Wu, Xiaohua,Xu, Dongcheng
-
p. 857 - 860
(2008/12/22)
-
- Cationic chiral dirhodium carboxamidates are activated for lewis acid catalysis
-
(Chemical Equation Presented) The power of a positive charge: Oxidized chiral dirhodium carboxamidate salts increase the rate of reaction of selected aldehydes with the Danishefsky diene (hetero-Diels-Alder reaction) and with nitrones (1,3-dipolar cycload
- Wang, Yuanhua,Wolf, Joffrey,Zavalij, Peter,Doyle, Michael P.
-
p. 1439 - 1442
(2008/12/23)
-
- BINOlate-magnesium catalysts for enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with aldehydes
-
An efficient catalytic enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with aldehydes using the magnesium binaphthoxide system has been developed, affording a variety of 2-substituted 2,3-dihydro-4H-pyran-4-ones in high yields and with
- Du, Haifeng,Zhang, Xue,Wang, Zheng,Bao, Hongli,You, Tianpa,Ding, Kuiling
-
scheme or table
p. 2248 - 2254
(2009/04/08)
-
- Improvement of the reactivity and selectivity of the oxo-Diels-Alder reaction by steric modification of the salen-chromium catalyst
-
Salen-chromium(III) complexes bearing sterically demanding substituents at the 3 and 3′ positions are applied for the oxo-Diels-Alder reaction of various aldehydes with Danishefsky's diene. The readily-accessible complex bearing a bulky 3-phenylpent-3-yl substituent revealed its potential affording the cycloadducts with improved reactivity and excellent selectivities up to 96% ee, being considerably superior to the classic Jacobsen's catalyst.
- Cha?adaj, Wojciech,Kwiatkowski, Piotr,Jurczak, Janusz
-
scheme or table
p. 6810 - 6811
(2009/04/07)
-
- Storable, powdered chiral zirconium complex for asymmetric aldol and hetero Diels-Alder reactions
-
A storable, powdered chiral zirconium catalyst for asymmetric aldol and hetero Diels-Alder reactions has been developed. The catalyst has the same activity as that prepared in situ even after being stored for 3 months. Moreover, this chiral Zr catalyst wo
- Seki, Kazutaka,Ueno, Masaharu,Kobayashi, Shu
-
p. 1347 - 1350
(2008/01/01)
-
- Systematically probing the effect of catalyst acidity in a hydrogen-bond-catalyzed enantioselective reaction
-
(Chemical Equation Presented) Defining the relationship: The effect of catalyst acidity has been systematically probed by using a modular oxazoline catalyst in a hetero-Diels-Alder reaction catalyzed by hydrogen bonding. Linear free energy relationships w
- Jensen, Katrina H.,Sigman, Matthew S.
-
p. 4748 - 4750
(2008/02/10)
-
- Methods of performing cycloadditions, reaction mixtures, and methods of performing asymmetric catalytic reactions
-
Methods of performing cycloadditions are described that include (a) combining a first reactant and a second reactant in a hydrogen bonding solvent to form a reaction mixture; and (b) reacting the first reactant and the second reactant to form a cycloadduc
- -
-
Page/Page column 23-24; 33-34
(2010/11/27)
-
- Experimental and theoretical studies on the hydrogen-bond-promoted enantioselective hetero-Diels-Alder reaction of Danishefsky's diene with benzaldehyde
-
The enantioselective hetero-Diels-Alder (HDA) reaction of Danishefsky's diene with benzaldehyde has been achieved catalytically by a series of α,α,α′,α′-tetraaryl-1,3-dioxolane-4, 5-dimethanol (TADDOL) derivatives through hydrogen-bonding activation, affo
- Zhang, Xue,Du, Haifeng,Wang, Zheng,Wu, Yun-Dong,Ding, Kuiling
-
p. 2862 - 2869
(2007/10/03)
-
- Chiral chromium(III) porphyrins as highly enantioselective catalysts for Hetero-Diels-Alder reactions between aldehydes and dienes
-
Starting from enantiomerically pure 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2, 3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene-9-yl]porphyrin, treatment with CrCl2 and subsequent air oxidation afforded the corresponding Cr(III) complex, with chlo
- Berkessel, Albrecht,Ertuerk, Erkan,Laporte, Cecile
-
p. 223 - 228
(2007/10/03)
-
- Polyglycerol-supported chromium-salen as a high-loading dendritic catalyst for stereoselective Diels-Alder reactions
-
In this paper we demonstrate the application of hyperbranched polyglycerol (PG) 3 as a polymeric support for asymmetric catalysis. A new polyglycerol-supported unsymmetrical salen ligand 4 is described, which was successfully purified by gel permeation chromatography (GPC) or by ultrafiltration. After the insertion of the metal, e.g., chromium, the corresponding polymeric chromium complex was used as catalyst for asymmetric Diels-Alder reactions between Danishefsky's diene and benzaldehyde. The catalytic activities (up to 98% conversion) and enantioselectivities (up to 78% ee) were comparable to the original catalyst reported by Jacobsen. The soluble polyglycerol-supported catalysts were recovered by dialysis after the catalytic reactions and were recycled two times to afford identical reactivities as in the first run, with slightly reduced enantioselectivities. Moreover, this polymeric support catalyst showed a high retention (99.02%) in a continuously operated membrane reactor.
- Hajji, Chakib,Roller, Sebastian,Beigi, Maryam,Liese, Andreas,Haag, Rainer
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p. 1760 - 1771
(2007/10/03)
-
- DIANANE-CrIII-salen complexes as highly enantioselective catalysts for hetero-Diels-Alder reactions of aldehydes with dienes
-
A new type of chromium-salen complex bearing DIANANE (endo,endo-2,5- diaminonorbornane) as chiral backbone has been synthesized and applied to the hetero-Diels-Alder reaction of Danishefsky's diene with various aldehydes. The reactions afford the correspo
- Berkessel, Albrecht,Vogl, Nadine
-
p. 5029 - 5035
(2007/10/03)
-
- Design of hydrogen bond catalysts based on a modular oxazoline template: Application to an enantioselective hetero Diels-Alder reaction
-
(Chemical Equation Presented) A catalyst system that displays two hydrogen bond donating arms from a rigid oxazoline backbone and its utility in a hydrogen bond promoted enantioselective hetero Diels-Alder reaction are described.
- Rajaram, Sridhar,Sigman, Matthew S.
-
p. 5473 - 5475
(2007/10/03)
-
- One catalyst for two distinct reactions: Sequential asymmetric hetero Diels-Alder reaction and diethylzinc addition
-
This paper describes the successful development of a series of chiral zinc catalysts containing (R)-3,3′-Br2-BINOL ligand and various diimine activators for enantioselective HDA reaction of Danishefsky's diene with aldehydes through a combinato
- Du, Haifeng,Zhang, Xue,Wang, Zheng,Ding, Kuiling
-
p. 9465 - 9477
(2007/10/03)
-
- Axially chiral biaryl diols catalyze highly enantioselective hetero-diels-alder reactions through hydrogen bonding
-
Axially chiral 1,1′-biaryl-2,2′-dimethanol (3, BAMOL) family of diols are highly effective catalysts for enantioselective hetero-Diels-Alder reactions between aminosiloxydiene 1 and a wide variety of unactivated aldehydes. The reactions proceed in useful
- Unni, Aditya K.,Takenaka, Norito,Yamamoto, Hisashi,Rawal, Viresh H.
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p. 1336 - 1337
(2007/10/03)
-
- A new dirhodium(II) carboxamidate complex as a chiral Lewis acid catalyst for enantioselective hetero-Diels-Alder reactions
-
Excellent enantioselectivities (up to 99% ee) and turnover numbers (up to 48000) were attained in the hetero-Diels-Alder reaction of a diverse range of aldehydes and activated dienes catalyzed by [Rh2(S-bptpi) 4] (see scheme).
- Anada, Masahiro,Washio, Takuya,Shimada, Naoyuki,Kitagaki, Shinji,Nakajima, Makoto,Shiro, Motoo,Hashimoto, Shunichi
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p. 2665 - 2668
(2007/10/03)
-
- Enantioselective catalysis of hetero Diels-Alder reaction and diethylzinc addition using a single catalyst
-
(Matrix presented) Integration of two asymmetric reactions in one pot with the promotion of a single catalyst has been achieved in high efficiency and excellent stereoselectivity for hetero Diels-Alder reaction of Danishefsky's diene and diethylzinc addit
- Du, Haifeng,Ding, Kuiling
-
p. 1091 - 1093
(2007/10/03)
-
- Chiral hetero Diels-Alder products by enantioselective and diastereoselective zirconium catalysis. Scope, limitation, mechanism, and application to the concise synthesis of (+)-prelactone C and (+)-9-deoxygoniopypyrone
-
Catalytic asymmetric hetero Diels-Alder (HDA) reactions using a chiral zirconium complex have been developed. The reactions of aldehydes with Danishefsky's dienes proceeded smoothly to afford the corresponding pyranone derivatives in high yields with high diastereo- and enantioselectivities in the presence of a chiral zirconium complex, which was prepared from zirconium tert-butoxide, (R)-3,3′-diiodobinaphthol or its derivative, a primary alcohol, and a small amount of water. It is noted that 2,3-trans-pyranone derivatives were obtained with remarkably high diastereo- and enantioselectivities in the reaction with 4-methyl Danishefsky's diene. This is the first example of catalytic asymmetric trans-selective hetero Diels-Alder reactions of aldehydes. Furthermore, asymmetric HDA reactions with 4-benzyloxy Danishefsky's dienes were conducted to afford 2,3-cis-pyranone derivatives in high selectivities. Isolation of an intermediate of this asymmetric hetero Diels-Alder reaction indicated that the reaction proceeded in a stepwise cycloaddition pathway. Finally, these catalytic, asymmetric hetero Diels-Alder reactions were successfully applied to concise syntheses of biologically important natural pyranone derivatives, (+)-Prelactone C and (+)-9- deoxygoniopypyrone.
- Yamashita, Yasuhiro,Saito, Susumu,Ishitani, Haruro,Kobayashi, Shu
-
p. 3793 - 3798
(2007/10/03)
-
- Highly enantioselective homogeneous catalysis of chiral rare earth phosphates in the hetero-Diels-Alder reaction
-
Two types of novel rare earth (RE) complexes were synthesized and used as a chiral Lewis acid catalyst for the hetero-Diels-Alder reaction of carbonyl compounds with the Danishefsky's diene under homogeneous conditions. The Y[(R)-H8-BNP]3
- Furuno, Hiroshi,Kambara, Takeshi,Tanaka, Yumiko,Hanamoto, Takeshi,Kagawa, Takumi,Inanaga, Junji
-
p. 6129 - 6132
(2007/10/03)
-
- Asymmetric Diels-Alder reactions in supercritical carbon dioxide catalyzed by rare earth complexes
-
The rare earth(III) salt catalysed asymmetric Diels-Alder reaction of cyclopentadiene with a chiral dienophile in supercritical carbon dioxide (scCO2) proceeded rapidly to give the adduct with a higher diastereoselectivity than that in dichloro
- Fukuzawa, Shin-Ichi,Metoki, Ken,Esumi, Shin-Ichi
-
p. 10445 - 10452
(2007/10/03)
-
- Chiral rare earth organophosphates as homogeneous Lewis acid catalysts for the highly enantioselective hetero-Diels-Alder reactions
-
Various trivalent rare earth-chiral phosphate complexes [(R)-1-RE, (R)-3-RE, and (R)-4-Ce] were prepared and evaluated as a Lewis acid catalyst for the asymmetric hetero-Diels-Alder reaction of aldehydes with the Danishefsky's diene. Some of them effectiv
- Furuno, Hiroshi,Hayano, Tetsuji,Kambara, Takeshi,Sugimoto, Yuichi,Hanamoto, Takeshi,Tanaka, Yumiko,Jin, Yong Zhi,Kagawa, Takumi,Inanaga, Junji
-
p. 10509 - 10523
(2007/10/03)
-
- Assembled Dendritic Titanium Catalysts for Enantioselective Hetero-Diels-Alder Reaction of Aldehydes with Danishefsky's Diene
-
A new type of dendritic 2-amino-2′-hydroxy-1,1′-binaphthyl (NOBIN)-derived Schiff-base ligands have been synthesized and applied to the titanium-catalyzed hetero-Diels-Alder reaction of Danishefsky's diene with aldehydes. These reactions afforded the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-ones in quantitative yields and with excellent enantioselectivities (up to 97.2% ee). The disposition of the dendritic wedges and the dendron size in the ligands were found to have significant impact on the enantioselectivity of the reaction. The recovered dendritic catalyst could be reused without further addition of the Ti source or a carboxylic acid additive for at least three cycles, retaining similar activity and enantioselectivity. The high stability of this type of assembled dendritic titanium catalyst may be attributed to the stabilization effect of large-sized dendron units in the catalyst molecule. The other important phenomenon observed with this catalyst system is that a higher degree of asymmetric amplification has been achieved by attachment of the dendron unit to the chiral ligand, which represents a new advantage of dendrimer catalysts for asymmetric reactions using chiral ligands of lower optical purity.
- Ji, Baoming,Yuan, Yu,Ding, Kuiling,Meng, Jiben
-
p. 5989 - 5996
(2007/10/03)
-
- Enantioselective heterogeneous epoxidation and hetero-Diels-Alder reaction with Mn- and Cr-salen complexes immobilized on silica gel by radical grafting
-
Vinyl-substituted chiral salens (salen = bis(salicylidene)ethylidenediamine) are used for attachment to Me3Si-hydrophobized silica gel (controlled-pore glass, CPG), carrying covalently bound mercaptopropyl 'substituents', by AIBN-mediated radic
- Heckel, Alexander,Seebach, Dieter
-
p. 913 - 926
(2007/10/03)
-
- Catalytic, enantioselective hetero-Diels-Alder reaction with novel, chiral bis-titanium(IV) catalyst
-
Our recently designed chiral bis-titanium(IV) catalyst can be successfully utilized for the catalytic enantioselective hetero-Diels-Alder reaction of aldehyde and Danishefsky's diene. The high asymmetric induction is achievable in the case of sterically l
- Kii, Satoshi,Hashimoto, Takuya,Maruoka, Keiji
-
p. 931 - 932
(2007/10/03)
-
- To probe the origin of activation effect of carboxylic acid and (+)-NLE in tridentated titanium catalyst systems
-
The activation effect of carboxylic acid and positive nonlinear effect ((+)-NLE) in tridentated titanium catalyst systems for hetero Diels-Alder reaction and aldol-type reactions has been first elucidated on the basis of X-ray crystal structural analysis
- Yuan, Yu,Li, Xin,Sun, Jie,Ding, Kuiling
-
p. 14866 - 14867
(2007/10/03)
-
- 3,3′-Br2-BINOL-Zn complex: A highly efficient catalyst for the enantioselective hetero-Diels-Alder reaction
-
(equation presented) A BINOLate-zinc complex prepared in situ from Et2Zn and 3,3′-dibromo-1,1′-bi-2-naphthol (3,3′-Br2-BINOL) was found to be a highly efficient catalyst for the enantioselective hetero-Diels-Alder reaction of Danishe
- Du, Haifeng,Long, Jiang,Hu, Jieyu,Li, Xin,Ding, Kuiling
-
p. 4349 - 4352
(2007/10/03)
-
- Asymmetric cycloaddition reactions
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The present invention relates to a process for stereoselective cycloaddition reactions which generally comprises a cycloaddition reaction between a pair of substrates, each either chiral or prochiral, that contain reactive π-systems, in the presence of a non-racemic chiral catalyst, to produce a stereoisomerically enriched product. The present invention also relates to novel asymmetric catalyst complexes comprising a metal and an asymmetric tridentate ligand.
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Page column 40-41
(2010/01/31)
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- Catalytic, Asymmetric trans-Selective Hetero Diels-Alder Reactions Using a Chiral Zirconium Complex
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matrix presented The first catalytic, asymmetric 2,3-trans-selective hetero Diels-Alder reaction has been developed. The reactions of aldehydes with Danishefsky's dienes proceeded smoothly to afford the pyranone derivatives in high yields with high trans-
- Yamashita, Yasuhiro,Saito, Susumu,Ishitani, Haruro,Kobayashi, Shu
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p. 1221 - 1223
(2007/10/03)
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- Discovery of exceptionally efficient catalysts for solvent-free enantioselective hetero-Diels-Alder reaction
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Combinatorial coordination chemistry strategy combined with high-throughput screening techniques has been successfully applied to engineering practical enantioselective catalysts for asymmetric hetero-Diels-Alder reaction. The reaction of Danishefsky's di
- Long,Hu,Shen,Ji,Ding
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- A highly enantioselective hetero-Diels-Alder reaction of aldehydes with Danishefsky's diene catalyzed by chiral titanium(IV) 5,5′,6,6′,7,7′,8,8′-octahydro-1,1′ -bi-2-naphthol complexes
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The catalytic effect of chiral Lewis acids on the hetero-Diels-Alder reaction between aldehydes and Danishefsky's diene (1) has been investigated. A variety of combinations of different ligands and Lewis acids have been examined as catalysts for the heter
- Wang, Bin,Feng, Xiaoming,Huang, Yaozong,Liu, Hui,Cui, Xin,Jiang, Yaozhong
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p. 2175 - 2182
(2007/10/03)
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- Preparation of dendritic and non-dendritic styryl-substituted Salens for cross-linking suspension copolymerization with styrene and multiple use of the corresponding Mn and Cr complexes in enantioselective epoxidations and Hetero-Diels - Alder reactions
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Following work with TAD-DOLs and BINOLs, we have now prepared Salen derivatives (2, 3, 14, 15, 18, 19, 20, 21) carrying two to eight styryl groups for cross-linking copolymerization with styrene. The Salen cores are either derived from (R,R)-diphenyl ethylene diamine (3, 15, 19, 21) or from (R,R)-cyclohexane diamine (2, 14, 18, 20). The styryl groups are attached to the salicylic aldehyde moieties, using Suzuki (cf. 1) or Sonogashira cross-coupling (cf. 11), and/or phenolic etherification (cf. 5, 7) with dendritic styryl-substituted Frechet-type benzylic branch bromides. Subsequent condensation with the diamines provides the chiral Salens. Corresponding Salens lacking the peripheral vinyl groups (cf. 12, 13, 16, 17) were also prepared for comparison of catalytic activities in homogeneous solution with those in polystyrene. Cross-linking radical suspension copolymerization of styrene and the styryl Salens, following a procedure by Itsuno and Frechet, gave beads (ca. 400 μm diameter) which were loaded with Mn or Cr (ca. 0.2 mmol of complex per g of polymer), with more than 95 % of the Salen incorporated being actually accessible for complexation (by elemental analysis). The polymer-bound Mn and Cr complexes were used as catalysts for epoxidations of six phenyl-substituted olefins (m-CPBA/NMO; products 22 a-f), and for dihydropyranone formation from the Danishefsky diene and aldehydes (PhCHO, C5H11CHO, C6H11CHO, products 23a-c). There are several remarkable features of the novel immobilized Salens: i) The dendritic branches do not slow down the catalytic activity of the complexes in solution; ii) the reactions with Salen catalysts incorporated in polystyrene give products of essentially the same enantiopurity as those observed in homogeneous solution with the dendritically substituted or with the original Jacobsen-Katsuki complexes; iii) some Mn-loaded beads have been stored for a year, without loss of activity; iv) especially the biphenyl- and the acetylene-linked Salen polymers (p-2, -3, -20, -21, Figure 2, 3) give Mn complexes of excellent performance: after ten uses (without re-charging with Mn!) there is no loss of enantioselectivity or degree of conversion under the standard conditions. Wiley-VCH Verlag GmbH, 2001.
- Sellner, Holger,Karjalainen, Jaana K.,Seebach, Dieter
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p. 2873 - 2887
(2007/10/03)
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