- 2,2′-Bipyridine-α,α′-trifluoromethyl-diol ligand: Synthesis and application in the asymmetric Et2Zn alkylation of aldehydes
-
A chiral 2,2′-bipyridine ligand (1) bearing α,α′-trifluoromethyl-alcohols at 6,6′-positions was designed in five steps affording either the R,R or S,S enantiomer with excellent stereoselectivities, i.e. 97% de, >99% ee and >99.5% de, >99.5% ee, respectively. The key step for reaching high levels of stereoselectivity was demonstrated to be the resolution of the α-CF3-alcohol using (S)-ibuprofen as the resolving agent. An initial application for the 2,2′-bipyridine-α,α′-CF3-diol ligand was highlighted in the ZnII-catalyzed asymmetric ethylation reaction of aromatic, heteroaromatic, and aliphatic aldehydes. Synergistic electron deficiency and steric hindrance properties of the newly developed ligand afforded the corresponding alcohols in good to excellent yields (up to 99%) and enantioselectivities (up to 95% ee). As observed from single crystal diffraction analysis, the complexation of the 2,2′-bipyridine-α,α′-CF3-diol ligand generates an unusual hexacoordinated ZnII.
- Lauzon, Samuel,Ollevier, Thierry
-
supporting information
p. 11025 - 11028
(2021/11/03)
-
- Electrochemical Aziridination of Internal Alkenes with Primary Amines
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An electrochemical approach to prepare aziridines via an oxidative coupling between alkenes and primary alkyl amines was realized. The reaction is carried out in an electrochemical flow reactor, leading to short reaction/residence times (5 min), high yields, and broad scope. At the cathode, hydrogen is generated, which can be used in a second reactor to reduce the aziridine yielding the corresponding hydroaminated product.Aziridines are useful synthetic building blocks, widely employed for the preparation of various nitrogen-containing derivatives. As the current methods require the use of prefunctionalized amines, the development of a synthetic strategy toward aziridines that can establish the union of alkenes and amines would be of great synthetic value. Herein, we report an electrochemical approach, which realizes this concept via an oxidative coupling between alkenes and primary alkylamines. The reaction is carried out in an electrochemical flow reactor leading to short reaction/residence times (5 min), high yields, and broad scope. At the cathode, hydrogen is generated, which can be used in a second reactor to reduce the aziridine, yielding the corresponding hydroaminated product. Mechanistic investigations and DFT calculations revealed that the alkene is first anodically oxidized and subsequently reacted with the amine coupling partner.The central tenet in modern synthetic methodology is to develop new methods only using widely available organic building blocks. As a direct consequence, new activation strategies are required to cajole the coupling partners to react and, subsequently, forge new and useful chemical bonds. Using electrochemical activation, our methodology enables for the first time the direct coupling between olefins and amines to yield aziridines. Aziridines display interesting pharmacological activity and serve as valuable synthetic intermediates to prepare diverse nitrogen-containing derivatives. Interestingly, the sole byproduct generated in this process is hydrogen, which can be subsequently used to reduce the aziridine into the corresponding hydroaminated product. Hence, this electrochemical methodology can be regarded as green and sustainable from the vantage point of upgrading simple and widely available commodity chemicals.
- Bartolomeu, Aloisio de A.,Dyga, Marco,Goo?en, Lukas J.,Laudadio, Gabriele,No?l, Timothy,O?eka, Maksim,de Bruin, Bas,de Oliveira, Kleber T.,van Leest, Nicolaas P.
-
supporting information
p. 255 - 266
(2021/01/19)
-
- Linear β-amino alcohol catalyst anchored on functionalized magnetite nanoparticles for enantioselective addition of dialkylzinc to aromatic aldehydes
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A linear β-amino alcohol ligand, previously found to be a very efficient catalyst for enantioselective addition of dialkylzinc to aromatic aldehydes, has been anchored on differently functionalized superparamagnetic core-shell magnetite-silica nanoparticles (1a and 1b). Its catalytic activity in the addition of dialkylzinc to aldehydes has been evaluated, leading to promising results, especially in the case of 1b for which the recovery by simple magnetic decantation and reuse was successfully verified. This journal is
- Ciprioti, Stefano Vecchio,De Angelis, Martina,Di Pietro, Federica,Iannoni, Marika,Pilloni, Luciano,Primitivo, Ludovica,Ricelli, Alessandra,Righi, Francesco,Righi, Giuliana,Sappino, Carla,Suber, Lorenza
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p. 29688 - 29695
(2020/10/26)
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- Chirality-Economy Catalysis: Asymmetric Transfer Hydrogenation of Ketones by Ru-Catalysts of Minimal Stereogenicity
-
This manuscript describes the design and synthesis of Ru catalysts that feature only a single stereogenic element, yet this minimal chirality resource is demonstrated to be competent for effecting high levels of stereoinduction in the asymmetric transfer hydrogenation over a broad range of ketone substrates, including those that are not accommodated by known catalyst systems. The single stereogenic center of the (1-pyridine-2-yl)methanamine) is the only point-chirality in the catalysts, which simplifies this catalyst system relative to existing literature protocols.
- Chen, Fumin,He, Dongxu,Chen, Li,Chang, Xiaoyong,Wang, David Zhigang,Xu, Chen,Xing, Xiangyou
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p. 5562 - 5566
(2019/06/05)
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- Chiral zinc amidate catalyzed additions of diethylzinc to aldehydes
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A series of bifunctional spiro ligands bearing “carboxamide–phosphine oxide” groups and ethylzinc carboxamidates from these ligands as catalysts for Et2Zn additions to aldehydes were reported. Excellent yields were obtained with moderate ee′s in Et2Zn additions to benzaldehyde derivatives, implying effectiveness of our newly designed catalytic structures as well as mediocre stereocontrol by these chiral ligands. Possible transition states were suggested based on the crystal structures of two ligands.
- Zhang, Jinxia,Li, Shasha,Zheng, Xinxin,Li, Hongjie,Jiao, Peng
-
supporting information
p. 1913 - 1917
(2019/06/24)
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- New chiral amino alcohol ligands for catalytic enantioselective addition of diethylzincs to aldehydes
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A study aimed at the synthesis and structure optimization of new, efficient, optically active β-amino alcohol ligands with a structure suitable for immobilization on magnetite nanoparticles has been carried out. The optimized homogeneous amino alcohol catalysts 13a and 13b, the chirality of which arises from the Sharpless epoxidation of suitable allyl alcohols, were tested by employing the well-established enantioselective amino alcohol-promoted addition of diethylzinc to benzaldehyde, giving the corresponding benzyl alcohol with nearly quantitative yield and ee = 95%. Then, their broad applicability as chiral catalysts was evaluated by carrying out the same reaction on a family of aldehydes, including variously substituted aromatic ones as well as an aliphatic analogue. The results have confirmed the validity of the fine-tuning process performed on ligands 13a and 13b. In fact, both exhibited excellent catalytic activity as demonstrated by the chemical yields and ee obtained from all the tested aldehydes, almost independent of the position and type of substitution in the aromatic ring.
- Sappino, Carla,Mari, Alessandra,Mantineo, Agnese,Moliterno, Mauro,Palagri, Matteo,Tatangelo, Chiara,Suber, Lorenza,Bovicelli, Paolo,Ricelli, Alessandra,Righi, Giuliana
-
p. 1860 - 1870
(2018/03/23)
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- Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive Catalyst
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Recent advances in molecular design have displayed striking examples of dynamic chirality transfer between various elements of chirality, e.g., from central to either helical or axial chirality and vice versa. While considerable progress in atroposelective synthesis has been made, it is intriguing to design chiral molecular switches able to provide selective and dynamic control of axial chirality with an external stimulus to modulate stereochemical functions. Here, we report the synthesis and characterization of a photoresponsive bis(2-phenol)-substituted molecular switch 1. The unique design exhibits a dynamic hybrid central-helical-axial transfer of chirality. The change of preferential axial chirality in the biaryl motif is coupled to the reversible switching of helicity of the overcrowded alkene core, dictated by the fixed stereogenic center. The potential for dynamic control of axial chirality was demonstrated by using (R)-1 as switchable catalyst to direct the stereochemical outcome of the catalytic enantioselective addition of diethylzinc to aromatic aldehydes, with successful reversal of enantioselectivity for several substrates.
- Pizzolato, Stefano F.,?tacko, Peter,Kistemaker, Jos C. M.,Van Leeuwen, Thomas,Otten, Edwin,Feringa, Ben L.
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supporting information
p. 17278 - 17289
(2019/01/04)
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- Noscapine Derivatives as New Chiral Catalysts in Asymmetric Synthesis: Highly Enantioselective Addition of Diethylzinc to Aldehydes
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Noscapine, a natural alkaloid, has never been used as a parent scaffold in chiral induction. The first examples of noscapinoid compounds as efficient catalysts in asymmetric synthesis are now reported. Three derivatives of noscapine were synthesized from its reaction with different Grignard reagents. Asymmetric addition of diethylzinc to aldehydes was performed in the presence of these catalysts in high yields and good to excellentees.
- Mohebbi, Maryam,Bararjanian, Morteza,Ebrahimi, Samad N.,Smie?ko, Martin,Salehi, Peyman
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p. 1841 - 1848
(2018/02/14)
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- Chiral Lithium Amido Zincates for Enantioselective 1,2-Additions: Auto-assembling Reagents Involving a Fully Recyclable Ligand
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A methodology consisting in carrying out enantioselective nucleophilic 1,2-additions (ee values up to 97 %) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto-assemble when mixing, in a 1:1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully recoverable thanks to a simple acid–base wash, allowing being recycled and re-use without loss of stereochemical information.
- Rouen, Mathieu,Chaumont, Pauline,Barozzino-Consiglio, Gabriella,Maddaluno, Jacques,Harrison-Marchand, Anne
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supporting information
p. 9238 - 9242
(2018/06/04)
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- Fe-Catalyzed Cycloisomerization of Aryl Allenyl Ketones: Access to 3-Arylidene-indan-1-ones
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A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
- Teske, Johannes,Plietker, Bernd
-
supporting information
p. 2257 - 2260
(2018/04/27)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by o-xylylene-type chiral 1,4-amino alcohols with an aminal structure
-
A series of o-xylylene-type chiral 1,4-amino alcohols with an aminal structure was synthesized starting from (S)-2-(arylaminomethyl)pyrrolidine, o-bromobenzaldehyde, and a diaryl ketone. The enantioselective addition of diethylzinc to aldehydes was examined by using the 1,4-amino alcohols, and the corresponding chiral secondary alcohols were obtained with high enantioselectivities (up to 98% ee).
- Asami, Masatoshi,Hasome, Ayano,Yachi, Naoyuki,Hosoda, Naoya,Yamaguchi, Yoshitaka,Ito, Suguru
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p. 322 - 329
(2016/04/09)
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- Development of Axially Chiral Cyclo-Biaryldiol Ligands with Adjustable Dihedral Angles
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A new type of axially chiral cyclo-[1,1′-biphenyl]-2,2′-diol (CYCNOL) ligands with adjustable dihedral angles have been developed by varying the bridge chain length. Eight-, nine- and ten-membered cyclo-ligands were prepared and evaluated by using two representative examples: enantioselective additions of diethylzinc to aldehydes and organometallic reagents to enones. The results revealed that the fine regulation of dihedral angles through variation of the bridge chain length was effective in the asymmetric synthesis.
- Zhang, Pengxiang,Yu, Jipan,Peng, Fei,Wu, Xudong,Jie, Jiyang,Liu, Can,Tian, Hua,Yang, Haijun,Fu, Hua
-
supporting information
p. 17477 - 17484
(2016/11/23)
-
- D-Penicillamine and L-cysteine derived thiazolidine catalysts: an efficient approach to both enantiomers of secondary alcohols
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D-Penicillamine derived thiazolidine ligands were prepared in a two-step synthetic sequence and used in the enantioselective alkylation of a variety of aromatic aldehydes with diethylzinc at room temperature. Excellent ee, up to >99%, and nearly complete conversions were observed. Structurally analogous L-cysteine derived thiazolidine ligands were also synthesized and tested for comparative purposes, resulting in very good, albeit slightly lower selectivities, up to 89%. The combined use of these two types of thiazolidines constitutes a very interesting strategy for synthesizing both (S) and (R) enantiomers of chiral secondary alcohols, thus leading the way to a myriad of useful optically active products with opposite absolute configurations.
- Serra, M. Elisa Silva,Costa, Dora,Murtinho, Dina,Tavares, Nélia C.T.,Pinho e Melo, Teresa M.V.D.
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p. 5923 - 5927
(2016/09/07)
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- Preparation of several BINOL-based polymeric ligands for the enantioselective addition of triethylaluminium to aromatic aldehydes
-
The synthesis of several polystyrene-supported BINOL (1,1-binaphthol) ligands via radical polymerization is described. These BINOL-based polymeric ligands were applied to the enantioselective addition of triethylaluminium to aromatic aldehyde in the presence of titanium isopropoxide. The products were obtained with up to 93% enantiomeric excess (ee) in good to excellent yield. The ligands were easily recovered and reused without losing their catalytic activity as well as enantioselectivity.
- Liu, Dacai,Ouyang, Kunbing,Yang, Nianfa
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p. 1018 - 1023
(2016/01/30)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by (R)-1-phenylethylamine-derived 1,4-amino alcohols
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A series of o-xylylene-type 1,4-amino alcohols, synthesized from (R)-1-phenylethylamine, were used as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde. (S)-1-Phenyl-1-propanol was obtained with high enantioselectivity in all cases since the stereochemical outcome of the reaction was controlled by the chiral benzylic carbon bearing amino group. Highest catalytic activity was obtained by using (R)-1-{2-[1-(pyrrolidin-1-yl)ethyl]phenyl}cyclohexan-1-ol (1n) derived from (R)-1-(1-phenylethyl)pyrrolidine and cyclohexanone. Various chiral secondary alcohols were obtained by the reaction of diethylzinc and aldehydes in the presence of 1n within 2 h with good to high enantioselectivities.
- Asami, Masatoshi,Miyairi, Naomichi,Sasahara, Yukihiro,Ichikawa, Ken-Ichi,Hosoda, Naoya,Ito, Suguru
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p. 6796 - 6802
(2015/08/24)
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- N-Trityl-aziridinyl alcohols as highly efficient chiral catalysts in asymmetric additions of organozinc species to aldehydes
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A synthetic route leading to a series of new chiral catalysts containing the N-trityl-aziridine moiety and a primary and a secondary hydroxyl group as nucleophilic centers is described. All the new compounds have been tested as chiral catalysts in the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes, yielding the corresponding chiral alcohols in high chemical yields (up to 96%) and with excellent ee's of ca. 90%. The influence of the stereogenic centers located at the carbon atom bonded with the hydroxyl moiety and on the carbon of the aziridine ring on the stereochemistry of the addition reactions is also discussed.
- Jarzyski, Szymon,Lesniak, Stanislaw,Pieczonka, Adam M.,Rachwalski, Michal
-
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by diastereomeric 1,4-amino alcohols with o-xylylene skeleton
-
Two diastereomeric 1,4-amino alcohols with o-xylylene structure (S,R)-2 and (S,S)-3, synthesized from chiral 1,4-diol (S,S)-1, were utilized as chiral ligands for the enantioselective addition of diethylzinc to aldehydes. The stereochemical outcome of the reactions was controlled solely by the absolute configuration of the benzylic carbon bearing amino group, and both enantiomers of 1-substituted propanol were obtained with up to 98% (S) and 96% (R) enantiomeric excesses.
- Asami, Masatoshi,Nagai, Atsushi,Sasahara, Yukihiro,Ichikawa, Ken-Ichi,Ito, Suguru,Hosoda, Naoya
-
supporting information
p. 345 - 347
(2015/03/30)
-
- Facile synthesis and stereo-resolution of chiral 1,2,3-triazoles
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We describe herein the first facile synthesis of chiral triazoles through side chain functionalization. Readily available C-vinyl triazoles were used as starting materials, followed by sequential epoxidation, rearrangement and reduction to give the corresponding hydroxyl-triazoles. The CalB lipase catalyzed kinetic resolution gave enantiomerically pure (>99% ee) chiral triazoles in excellent yield. These new chiral TAs were also successfully applied as ligands in asymmetric addition of diethylzinc to aldehydes.
- Shi, Ye,Ye, Xiaohan,Gu, Qiang,Shi, Xiaodong,Song, Zhiguang
-
supporting information
p. 5407 - 5411
(2015/05/20)
-
- Enantioselective addition of diethylzinc to aldehydes catalyzed by aziridine carbinols
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Abstract A series of enantiopure aziridine carbinols were synthesized from commercially available starting materials (l-serine and piperonylaldehyde), and characterized by 1H NMR, 13C NMR, HRMS, and IR. Their enantioselective induction behaviors were evaluated as chiral ligands in the asymmetric addition of diethylzinc and phenylethynylzinc to aryl and α,β-unsaturated aldehydes. Chiral aziridine carbinol 1h was found to catalyze the asymmetric addition of diethylzinc to aldehydes at low catalyst loadings (as little as 1 mol %), and the conversion rates were close to quantitative (up to 97% yield) with good to excellent enantiomeric excesses (up to 98% ee). A possible catalytic reaction mechanism is proposed.
- Wang, Xiaojuan,Zhao, Wenxian,Li, Gaowei,Liu, Guanjun,Wang, Jin,Wang, Mincan,Liu, Lantao
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p. 815 - 820
(2015/08/18)
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- Synthesis of dendrimer-supported ferrocenylmethyl aziridino alcohol ligands and their application in asymmetric catalysis
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A series of N-ferrocenylmethyl aziridino alcohol ligands bearing Frchet-type dendrimers were synthesized and applied in the asymmetric addition of diethylzinc to aldehydes affording chiral alcohols in excellent yields (up to 99%) and excellent enantiosele
- Zhao, Wen-Xian,Liu, Nian,Li, Gao-Wei,Chen, Dong-Li,Zhang, An-An,Wang, Min-Can,Liu, Lantao
-
supporting information
p. 2924 - 2930
(2015/05/27)
-
- A new pyrrolidine-derived atropisomeric amino alcohol as a highly efficient chiral ligand for the asymmetric addition of diethylzinc to aldehydes
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A highly efficient pyrrolidine-derived atropisomeric amino alcohol, (Sa)-1-[2-diphenylhydroxymethyl-6-(trifluoromethyl)phenyl]-2-(1-pyrrolido)methyl-1H-pyrrole, has been synthesized as a chiral ligand for the enantioselective addition of diethylzinc to some prochiral aldehydes to afford (S)-alcohols. The conversion rates were close to quantitative with good to excellent enantiomeric excesses (up to 95% ee).
- Faigl, Ferenc,Erdélyi, Zsuzsa,Deák, Szilvia,Nyerges, Miklós,Mátrav?lgyi, Béla
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supporting information
p. 6891 - 6894
(2015/02/02)
-
- Straightforward access to chiral diol bidentate ligands: Their efficient enantioselective induction in the addition of diethylzinc to aromatic aldehydes
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Enantiopure C2-symmetric diol bidentate ligands have been synthesized in a straightforward manner through a three-step reaction with good yields. The synthesized C2-symmetric diol bidentate ligands were used in the addition of diethylzinc to various aromatic aldehydes, a general catalytic benchmark reaction, in order to assess their enantioselective induction properties. The enantioselective addition of diethylzinc to 1-naphthaldehyde and 3-chlorobenzaldehyde was achieved with an enantiomeric excess (ee) of up to 98%. All synthesized ligands were also evaluated in the addition of diethyzinc to aromatic aldehydes including an extra metal such as Ti(IV) (up to 99% ee).
- G?k, Yaar,Külolu, Soner,G?k, Halil Zeki,Kekec, Levent
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p. 835 - 838
(2015/02/19)
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- Limonene oxide derived aziridinyl alcohols as highly efficient catalysts for asymmetric additions of organozinc species to aldehydes
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The facile synthesis of a series of novel catalysts bearing a tertiary hydroxyl group and an aziridine moiety as chelating centers constructed on the scaffold derived from limonene oxide is described. The newly prepared compounds have been tested for the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes, affording the corresponding chiral alcohols in very high chemical yields (up to 96%) and with excellent ee's of ca. 95%.
- Rachwalski, Michal
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p. 219 - 223
(2014/03/21)
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- Enantioselectivity switch controlled by N,N′-di- or N,N,N′,N′-tetra-substituted chiral thiophosphorodiamide ligands, structural relatives of thioureas, in catalytic additions of diethylzinc to aldehydes
-
We have developed a series of new chiral thiophosphorodiamide ligands derived from (1R,2R)-(+)-1,2-diphenylethylenediamine, which are the structural relatives of thioureas. An investigation into their catalytic properties in asymmetric additions of diethylzinc to aldehydes has shown that N,N,N′,N′-tetra-substituted chiral thiophosphorodiamides can give (R)-secondary alcohols with up to 98% yield and 98% ee, while N,N′-di-substituted chiral thiophosphorodiamides give (S)-secondary alcohols with up to 99% yield and 97% ee values. The enantioselectivity switch is highly efficient with a broad substrate scope. We have also proposed hypothetical reaction pathways, which result in an enantioselectivity switch.
- Yue, Huifeng,Huang, Huayin,Bian, Guangling,Zong, Hua,Li, Fangling,Song, Ling
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p. 170 - 180
(2014/02/14)
-
- Asymmetric addition of triethylaluminium to aromatic aldehydes catalyzed by titanium-(5,5'-Biquinoline-6,6'-Diol) complexes
-
A novel convenient procedure for the resolution of 5,5'-biquinoline-6,6'- diol (BIQOL) was achieved by separating the corresponding diastereomeric mixture of (S)-(+)-camphorsulfonates on a semiprepared XDB-C8 column followed by hydrolysis. The efficient asymmetric addition of triethylaluminium to aromatic aldehydes catalyzed by Ti-(+)/(-)BIQOL complexes under mild conditions is described. The reactions led to the formation of 1-arylpropan-1-ol in up to 87.5% ee. Chirality 26:268-271, 2014. 2014 Wiley Periodicals, Inc.
- Chen, Qian,Ou, Jun,Chen, Guo-Shu,Liu, Tian-Hui,Xie, Bin,Liang, Hai-Bo,Xie, Li-Qiong,Chen, Yi-Xin
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p. 268 - 271
(2014/05/06)
-
- Aziridine ring-containing chiral ligands as highly efficient catalysts in asymmetric synthesis
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Enantiomerically pure bidentate heteroorganic ligands built on an achiral skeleton containing hydroxyl and aziridine moieties as nucleophilic centers, capable of binding various organometallic reagents, have proven to be highly efficient catalysts in the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes to give the desired chiral products in high chemical yields (up to 90%) and with ees of up to 95%. The influence of the stereogenic center located in the carbon atom in the aziridine moiety on the stereochemical course of the reaction is reported.
- Rachwalski, Michal,Jarzynski, Szymon,Lesniak, Stanislaw
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p. 421 - 425
(2013/06/27)
-
- Synthesis and evaluation of the catalytic properties of semicarbazides derived from N-triphenylmethyl-aziridine-2-carbohydrazides
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A straightforward synthesis of a series of new catalysts derived from N-triphenylmethyl-aziridine-2-carbohydrazides is described. The new compounds have been tested for the enantioselective addition of diethyl- and phenylethynylzinc to aryl and alkyl aldehydes, which afforded the corresponding chiral alcohols in high chemical yields (up to 92%) and with excellent ee's of approximately 90%.
- Lesniak, Stanislaw,Pieczonka, Adam M.,Jarzynski, Szymon,Justyna, Katarzyna,Rachwalski, Michal
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p. 1341 - 1344
(2013/11/19)
-
- Synergistic effect of achiral quaternary ammonium salt on asymmetric additions of diethylzinc to aldehydes
-
Our investigation has shown that achiral quaternary ammonium salt has a significant synergistic effect on the asymmetric additions of diethylzinc to aldehydes catalyzed by chiral phosphoramide-Zn(II) complex. The addition of 10 mol % NBu4X can dramatically reduce the loading amount of chiral ligand without sacrificing the excellent reactivity and enantioselectivity of the asymmetric reaction.
- Zong, Hua,Huang, Huayin,Bian, Guangling,Song, Ling
-
supporting information
p. 2722 - 2725
(2013/06/26)
-
- Highly efficient asymmetric additions of diethylzinc to aldehydes triply activated by chiral phosphoramide-Zn(II) complexes derived from cinchona alkaloids
-
New chiral phosphoramide ligands derived from cinchona alkaloids were developed, which react with diethylzinc to form chiral phosphoramide-Zn(II) complexes containing two Lewis bases and one Lewis acid. These trifunctional complexes can serve as highly efficient chiral catalysts for triple activation of enantioselective addition reactions of diethylzinc with aldehydes to give desired alcohol products with excellent yields and enantiomeric excess (ee) values up to 99%. 2013 Wiley Periodicals, Inc.
- Shen, Bin,Huang, Huayin,Bian, Guangling,Zong, Hua,Song, Ling
-
p. 561 - 566
(2013/09/12)
-
- Synthesis of 1,3-aminonaphthols by diastereoselective Betti-type aminoalkylation of dihydroxy naphthalenes; Diastereoselectivity, absolute configuration, and application
-
Dihydroxy naphthalenes have been applied in Betti-type solventless condensation between aldehydes and (S)-phenylethylamine as a chiral auxiliary. A series of chiral 1,3-aminonaphthols has been synthesized and isolated in diastereoisomerically pure form. The absolute configurations of the aminonaphthols synthesized have been determined by means of advanced NMR experiments and confirmed by X-ray crystallography. The new chiral aminonaphthols have been tested as pre-catalysts for the addition of diethyl zinc and alkynyl-Zn-reagents to aldehydes with enantioselectivities of up to 98% ee.
- Marinova, Maya,Kostova, Kalina,Tzvetkova, Pavleta,Tavlinova-Kirilova, Maya,Chimov, Angel,Nikolova, Rosica,Shivachev, Boris,Dimitrov, Vladimir
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p. 1453 - 1466
(2013/12/04)
-
- Asymmetric preparation of new N, N -dialkyl-2-amino-1,1,2-triphenylethanol catalysts and a kinetic resolution in the addition of diethylzinc to flavene-3-carbaldehydes
-
Enantiopure N,N-dialkyl-(S)-2-amino-1,1,2-triphenylethanols were prepared using a new synthetic methodology and tested for their ability to catalyze the enantioselective addition of diethylzinc to aldehydes. The structural modification of N-substituents of the catalysts led us to identify N-methyl-N-(S)-1-phenyl-ethyl-substituted 4d as an effective catalyst for the addition. Also disclosed is a kinetic resolution of racemic flavene-3- carbaldehydes with the chiral catalyst.
- Kang, Seockyong,Baek, Jinho,Ko, Yikyung,Im, Chan,Park, Yongsun
-
supporting information
p. 630 - 634
(2013/04/23)
-
- Polystyrene-supported (2S)-(-)-3-exo-piperazinoisoborneol: An efficient catalyst for the batch and continuous flow production of enantiopure alcohols
-
A polystyrene-supported analog (PS-PIB) of 3-exo-morpholinoisoborneol (MIB), designed for increased chemical stability, has been synthesized and used as a ligand in the asymmetric alkylation of aldehydes with Et2Zn. The supported ligand turned out to be highly active and enantioselective for a broad scope of substrates (92-99% ee), allowing repeated recycling. A single-pass, continuous flow process implemented with PS-PIB shows only a marginal decrease in conversion after 30 h of operation.
- Osorio-Planes, Laura,Rodriguez-Escrich, Carles,Pericas, Miquel A.
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supporting information; experimental part
p. 1816 - 1819
(2012/07/03)
-
- Synthesis and application of novel dithiane alcohol ligand based on chiral cyclopropane-backbone for asymmetric ethylation of aromatic aldehydes
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A novel chiral dithiane alcohol ligand, based on chiral cyclopropane-backbone, was easily prepared from (-)- 1R-cis-caronaldehyde. The chiral ligand was used in asymmetric ethylation of aromatic aldehydes to afford the corresponding secondary alcohols wit
- Na, Risong,Wang, Bo,Liu, Honglei,Bian, Qinghua,Zhong, Jiangchun,Wang, Min,Guo, Hongchao
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p. 622 - 627
(2013/02/23)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by (S)-1-alkyl-2-(arylamino)methylpyrrolidine
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Several chiral diamines, (S)-1-alkyl-2-(arylamino)methylpyrrolidine, were used as chiral catalysts for the enantioselective addition of diethylzinc to aldehydes. The best results were obtained by employing 0.15 equiv of (S)-2-anilinomethyl-1-benzylpyrrolidine, and chiral secondary alcohols were obtained with high enantiomeric excesses (up to 94% ee).
- Hosoda, Naoya,Ito, Hiroki,Takimoto, Tatsuya,Asami, Masatoshi
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p. 1014 - 1022
(2012/11/07)
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- Cheap and long-life reusable polymer for asymmetric organozinc catalysis based on camphor-derived hydroxyamides
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Polystyrene grafted with a chiral zinc-complexing camphor-derived N,N-disubstituted hydroxyamide is proposed as a new type of functional polymer of high reusability for the development of sustainable organozinc-catalyzed asymmetric reactions. The main goal of this new functional polymer is the ease of the hydroxyamide-moiety preparation (cheap chiral ligand obtained straightforwardly from an enantiopure starting material coming from the chiral pool), as well as its chemical robustness when compared with other related zinc-complexing functional groups. The latter allows the polymer to be active after multiple applications, without significant loss of its catalytic activity. This fact is exemplified by the design and preparation of a polymer functionalized with a bis(hydroxyamide) proved previously as active in the homogeneous enantioselective addition of diethylzinc to aldehydes. The result is a cheap functional polymer with a very high reusability (the enantioselectivity and chemical yield are maintained practically constant after 20 applications). Additionally, a methodology for the multicycle use of these functional polymers is presented. Copyright
- De Las Casas Engel, Tomas,Sanchez-Carnerero, Esther M.,Gallardo-Araya, Claudio M.,Jimenez, Florencio Moreno,Maroto, Beatriz Lora,De La Moya Cerero, Santiago,Sokolovskaya, Ekaterina
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p. 771 - 777,7
(2020/07/30)
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- Applications of conformational design: Rational resign of chiral ligands derived from a common chiral source for highly enantioselective preparations of (R)- and (S)-enantiomers of secondary alcohols
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A pair of diastereomers 7 and 8 were easily synthesized in only two steps from a single common chiral source according to the concept of conformation design. The efficiency of these chiral ligands was evaluated by their application to the asymmetric addition of diethylzinc to aldehydes. This catalytic asymmetric process afforded the a most efficient access to the (R)- and (S)-enantiomers of a given secondary alcohol with similarly outstanding enantioselectivities and high yields. Our results also showed that the control of the desired conformer's population by conformation design is a new and practical strategy for the rational and precise design of highly enantioselective chiral ligands for metal-catalyzed reactions. The mechanism and possible transition states for the catalytic asymmetric addition have been proposed on the basis of previous studies as well as the crystal structure of the chiral ligands 7 and 8.
- Wang, Min-Can,Wang, Yong-Hui,Li, Gao-Wei,Sun, Ping-Ping,Tian, Jie-Xi,Lu, Hui-Jie
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experimental part
p. 761 - 768
(2011/08/06)
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- Synthesis of chiral sulfoximines derived from 3-aminoquinazolinones and their catalysis of enantioselective diethylzinc addition to aldehydes
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A series of sulfoxides were sulfoximinated using oxidative addition of 3-aminoquinazolinones by lead tetraacetate in the presence of hexamethyldisilazane. They were applied for the first time in catalytic enantioselective addition to aromatic aldehydes with a product enantiopurity (ee) of 92% in the case of 2-methoxybenzaldehyde.
- Karabuga, Semistan,Cakici, Murat,Kazaz, Cavit,Sahin, Ertan,Kilic, Hamdullah,Ulukanli, Sabri
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experimental part
p. 7887 - 7896
(2011/12/04)
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- Synthesis of sterically constrained tricyclic pyrrolidinyl alcohol ligands for the enantioselective ethylation of aryl aldehydes: Assessment of the influence of ring strain and N-alkyl chain length on asymmetric induction
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A series of chiral sterically constrained tricyclic pyrrolidinyl alcohol ligands were synthesized from the appropriate amino acids, and a comparative study of the activity and selectivity of the ligands for the enantioselective ethylation of aromatic aldehydes was carried out. The results obtained were compared with those previously reported for related monocyclic analogues; it was found that the bicyclo[2.2.2]octane backbone fused to pyrrolidine and the groups attached to the carbinol centre, as well as the chain length of the β-amino alcohol, had a marked effect on the enantioselectivity. The enantioselective addition of dialkylzincs to aryl aldehydes in the presence of ligands with diethyl substituents on the carbinol carbon afforded (R)-sec-alcohols in up to 99% enantiomeric excess (ee).
- Sahin, Engin,Kilic, Hamdullah
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experimental part
p. 277 - 282
(2011/05/17)
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- Synthesis and asymmetric catalytic activity of (1S,1′S)-4,4′- biquinazoline-based primary amines
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A series of (1S,1′S)-4,4′-biquinazoline-based primary amines were prepared from natural amino acids via a six-step reaction sequence of protection and condensation followed by key synthetic steps including chlorination, nickel(0)-mediated homocoupling, and deprotection. These novel amines were screened for the asymmetric ethylation of aryl aldehydes to yield alcohols with an (S)-configuration with enantiomeric excesses (ee) varying from 2% to 95%.
- Cakici, Murat,Catir, Mustafa,Karabuga, Semistan,Ulukanli, Sabri,Kilic, Hamdullah
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experimental part
p. 300 - 308
(2011/05/17)
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- α-Pinene-type chiral Schiff bases as tridentate ligands in asymmetric addition reactions
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A group of tridentate Schiff bases derived from (+)-α-pinene were synthesized. The steric effects in the transition state, the importance of π-π stacking interactions as well as the electronic effects of aryl aldehydes according to Hammett constant values in the enantioselective addition of Et2Zn to aldehydes with the use of Schiff bases as chiral ligands are described. Also, a variety of aldehydes were cyanated using a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. The influence of a conjugated double-bond in the cyanation substrates on enantioselectivity was observed. The chemical structures of the chiral Schiff base-titanium alkoxide complexes are discussed based on their 1H and 13C NMR spectra. 3D models of the Zn2-complex catalyst and Ti-complex catalyst containing α-pinane-type Schiff bases based on X-ray diffraction experiments are postulated. The models presented were consistent with the reported chirality of the addition product and observed ee.
- Jaworska, Magdalena,Blocka, Ewelina,Kozakiewicz, Anna,Welniak, Miroslaw
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experimental part
p. 648 - 657
(2011/07/08)
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- Sugar-monophosphite ligands applied to the asymmetric Ni-catalyzed trialkylaluminum addition to aldehydes
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A series of readily available sugar-based phosphite ligands were applied to the Ni-catalyzed asymmetric trialkylaluminum additions to aldehydes. The ability of the catalysts to transfer chiral information to the product could be tuned by choosing suitable ligand components (configuration at C-3 of the furanoside backbone; the steric hindrance of the substituent at C-3 and the substituents/configuration of the biaryl phosphite moieties). Good enantioselectivities (ee's up to 84%) were obtained for several aryl aldehydes using several organoaluminum sources.
- Alegre, Sabina,Dieguez, Montserrat,Pmies, Oscar
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experimental part
p. 834 - 839
(2011/08/22)
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- Structural and electronic effects of oxazolidine ligands derived from (1R,2S)-ephedrine in the asymmetric addition of diethylzinc to aldehydes
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The purpose of this research was to determine the activity of chiral oxazolidine ligands prepared from (1R,2S)-ephedrine for the enantioselective addition of diethylzinc to aldehydes. The configuration on the newly formed C2 stereogenic center was determined as (2S) by X-ray structural analysis. Oxazolidine ligands reveal medium enantioselectivity with the ee exceeding 57%, and the yields obtained being 68-99%. The results indicate that the absolute configuration of the addition product depends not only on the N3-methyl as an important stereocontrol element but also on both the electronic and steric effects of the substrates and oxazolidine ligands.
- Blocka, Ewelina,Jaworska, Magdalena,Kozakiewicz, Anna,Welniak, Miroslaw,Wojtczak, Andrzej
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experimental part
p. 571 - 577
(2010/08/06)
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- (1R,5R)-1-(1-dimethylaminoethyl)-2-isopropylidene-5-methylcyclohexanol as a chiral ligand in the enantioselective addition of diethylzinc to aldehydes
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An efficient chiral ligand, (1R,5R)-1-(1-dimethylaminoethyl)-2- isopropylidene-5-methylcyclohexanol, has been developed for the enantioselective addition of diethylzinc to some prochiral aldehydes to afford S-alcohols. The overall conversion rate was 80-98% with excellent enantiomeric excess (79-98%). Georg Thieme Verlag Stuttgart ? New York.
- Yadav, Ashok K.,Kumar, Manoj,Yadav, Tripti,Jain, Renuka
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scheme or table
p. 712 - 714
(2010/06/13)
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- Structurally constrained C1-1,1′-bisisoquinoline-based chiral ligands: geometrical implications on enantioinduction in the addition of diethylzinc to aldehydes
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New highly constrained chiral C1-1,1′-bisisoquinoline ligands have been synthesized. X-ray crystallographic analysis of these ligands showed peculiar structural differences between the parent 1′,2′,3′,4′-tetrahydro-1,1′-bisisoquinolin e and its alkyl, acyl and sulfonyl derivatives. The consequences of their geometrical conformations on enantioinduction were examined by employing the enantioselective addition of diethylzinc to aldehydes. Such conformations greatly affected the catalytic efficiency of these ligands.
- Qi, Gao,Judeh, Zaher M.A.
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experimental part
p. 429 - 436
(2010/07/02)
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- Enantioselective addition of diethylzinc to aryl aldehydes catalyzed by novel chiral imino alcohol ligands
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The enantioselective alkylation of aryl aldehydes by diethylzinc in the presence of catalytic amounts of several novel chiral imino alcohol ligands, synthesized from the reaction of (R)-2-amino-1-butanol with aromatic aldehydes, was studied. The influence of temperature and ligand structure was investigated and enantioselectivity up to 81% was obtained.
- Salehi,Dabiri,Kozehgary
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experimental part
p. 100 - 106
(2010/10/21)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by d-glucosamine derivatives: Highly pronounced effect of trifluoromethylsulfonamide
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We present the synthesis of β-hydroxy sulfonamides derived from d-glucosamine and their application as ligands in titanium tetraisopropoxide promoted enantioselective addition of diethylzinc to benzaldehyde and selected aromatic and aliphatic aldehydes. The N-trifluoromethylosulfonamido-d-glucosamine derivative is one of the most active ligands known and only 1 mol% of the ligand is sufficient for efficient catalysis of diethylzinc addition. The reaction is highly enantioselective for some aromatic aldehydes and enantiomeric excess up to 99% was obtained.
- Bauer, Tomasz,Smoliński, S?awomir
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experimental part
p. 247 - 251
(2010/11/18)
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- Synthesis and application of 3-substituted (S)-binol as chiral ligands for the asymmetric ethylation of aldehydes
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A series of (S)-BINOL ligands substituted at the 3 position with some five-membered nitrogen-containing aromatic heterocycles were effectively prepared and their catalytic abilities were evaluated in the asymmetric addition of diethylzinc to benzaldehyde in the presence of titanium tetraisopropoxide. Under the optimized reaction conditions, titanium complex of (S)-3-(1H-benzimidazol-1-yl)-1,1′-bi-2-naphthol was found to be the most efficient catalyst for asymmetric ethylation of various aldehydes to generate the corresponding secondary alcohols in up to 99% yield and 91% ee.
- Zhang, Zhi-Guang,Dong, Zhi-Bing,Li, Jin-Shan
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experimental part
p. 820 - 826
(2010/11/21)
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- Synthesis and structural features of chiral cyclic squaramides and their application in asymmetric catalytic reaction
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We report the synthesis and structural elucidation of two series of chiral cyclic squaramides, i.e. six-and twelve-membered ring squaramides 4 and 6, based on the cyclobutenedione structure, containing enantiomerically pure (1R,2R)-1,2-diphenylethylenediamine as the chiral element. Compounds 4a-d obtained from alkylation of 3, crystallize in space groups of monoclinic P2 1, monoclinic P21, monoclinic chiral P212 121, and the orthorhombic C2221, respectively. For the first time the crystal structures of six-membered ring chiral cyclic squaramides are reported. These novel ligands have been tested in the enantioselective addition of diethylzinc to aryl aldehydes to give the corresponding alcohols in moderate yields, albeit with low enantioselectivity. ARKAT-USA, Inc.
- Jin, Xiaoqing,Min, Qiaoqiao,Zheng, Yangfan,Wang, Pengcheng,Zhu, Jun,Zhou, Hai-Bing
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experimental part
p. 322 - 335
(2011/03/17)
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- Perhydro-1,3-benzoxazines derived from (-)-8-aminomenthol as ligands for the catalytic enantioselective addition of diethylzinc to aldehydes
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The catalytic potency of a series of perhydro-1,3-benzoxazines prepared from (-)-8-aminomenthol was examined in the enantioselective addition of diethylzinc to aldehydes. When (2R,3S,3aS,4aR,6R,8aS)-2-isopropyl-6,9,9- trimethyl-3-phenyldecahydro-4aH-pyrrolo[2,1-b][1,3]benzoxazin-3-ol 7b was used as a chiral ligand, 1-substituted propanols with an (R)-configuration were obtained in high yields and enantiomeric excesses up to >99%. The catalyst can be recovered and used without any loss in its activity.
- Andres, Celia,Infante, Rebeca,Nieto, Javier
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experimental part
p. 2230 - 2237
(2010/11/04)
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- A BINOL-terpyridine-based multi-task catalyst for a sequential oxidation and asymmetric alkylation of alcohols
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Treatment of a BINOL-terpyridine compound with RuCl3 generates a Ru(II) complex (R)-6. This complex is found to be a novel multi-task catalyst capable of conducting a sequential oxidation and asymmetric alkyl addition to convert primary alcohols to chiral secondary alcohols. The terpyridine-Ru(II) site of (R)-6 catalyzes an efficient oxidation of primary alcohols to aldehydes which then undergo an enantioselective alkylation to generate chiral secondary alcohols when the BINOL site of (R)-6 is combined with ZnEt2 and Ti(OiPr)4.
- Chen, Xi,Liu, Qiang,Sun, Hong-Bao,Yu, Xiao-Qi,Pu, Lin
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scheme or table
p. 2345 - 2347
(2010/06/13)
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