- Preparation of several BINOL-based polymeric ligands for the enantioselective addition of triethylaluminium to aromatic aldehydes
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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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- ([2]Paracyclo[2](5,8)quinolinophan-2-yl)carbinols as catalysts for diethylzinc addition to aldehydes: Cooperative effects of planar and central chirality on the asymmetric induction
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A systematic study to assess the contribution of planar and central chirality to the asymmetric induction in the diethylzinc addition to aromatic and aliphatic aldehydes has been carried out using planar chiral quinolinophanylcarbinols (Rp)-1 and (Rp)-11 and diastereomeric quinolinophanylcarbinols (Rp,R)- and (R p,S)-5-8, exhibiting both planar and central chirality as catalysts. The stereochemistry of the addition process leading to aryl- or 1-alkylpropanols seems to be mostly controlled by the central chirality. Nevertheless, the planar chirality shows a remarkable cooperative effect on the degree of asymmetric induction, which turns out to be positive or negative depending on the configuration of the stereogenic carbon of the catalyst.
- Ricci, Giacomo,Ruzziconi, Renzo
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- Ketopinic acid derived bis(hydroxy amides) as cheap, chiral ligands for the enantioselective ethylation of aromatic aldehydes
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Readily accessible, C2- and pseudo-C2-symmetric bis(hydroxy amides), derived from, commercially available (+)-ketopinic acid and protic diamines, are promising, cheap, chiral ligands for the synthetically valuable, enantioselective a
- De Las Casas Engel, Tomas,Maroto, Beatriz Lora,De La Moya Cerero, Santiago
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- Readily available new pyridyl alcohols derived from D-glucose as ligands for the enantioselective addition of diethylzinc to aldehydes
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A series of new chiral ligands derived from D-glucose has been synthesized and applied in the enantioselective addition of diethylzinc to aldehydes. Up to 94.1% e.e. was obtained in the ethylation reactions. In contrast to the ligands derived from D-fructose, ligands derived from D-glucose gave the opposite asymmetric induction.
- Huang, Hanmin,Zheng, Zhuo,Chen, Huilin,Bai, Changmin,Wang, Junwei
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- Roadmap towards N-heterocyclic [2.2]paracyclophanes and their application in asymmetric catalysis
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A novel family of [2.2]paracyclophane derivatives is described. Different substituted pyrazole, triazole and pyrimidine moieties were introduced to the [2.2]paracyclophane scaffold and the products were characterized spectroscopically and by X-ray structu
- Busch, Mark,Cayir, Merve,Nieger, Martin,Thiel, Werner R.,Braese, Stefan
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- C2-symmetric N-(β-mercaptoethyl)pyrrolidine as a chiral catalyst ligand in the addition reaction of aldehydes and diethylzinc
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A chiral C2-symmetric N-(β-mercaptoethyl)pyrrolidine bearing 6-membered benzylidene acetal functionalities fused at the 2,3- and 4,5-positions was found to exhibit high efficiency in the asymmetric addition reaction of aldehydes with diethylzin
- Masaki,Satoh,Makihara,Shi
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- Highly enantioselective addition of diethylzinc to aldehydes catalyzed by a new chiral C2-symmetric Ti-diol complex
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A novel C2-symmetric chiral diol was synthesized and was found to catalyze the enantioselective addition of diethylzinc to aldehydes to afford optically active secondary alcohols with ee's up to 99%.
- Yang, Xiao-Wu,Shen, Jian-Heng,Da, Chao-Shan,Wang, Heng-Shan,Su, Wu,Liu, Da-Xue,Wang, Rui,Choi, Michael C.K.,Chan, Albert S.C.
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- The effect of high pressure on the diastereoselectivity of intermolecular all-carbon Diels-Alder reactions
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The influence of high pressure on the diastereoselectivity of the intermolecular all-carbon Diels-Alder reaction of the phenylbutadienes 1 a- c with the dicyanoethylenes 2a-d to give the cyclohexenes 3-8 is described. The differences in activation volume, ΔΔV(≠), for the two pathways leading to cis and trans diastereomers range from - (0.7 ± 0.8) to - (6.4 ± 0.6) cm3mol-1 indicating a pressure-induced increase of diastereoselectivity in favour of the cis adducts 3a-d, 5a-d and 7b-d.
- Tietze, Lutz F.,Henrich, Marielouise,Niklaus, Anja,Buback, Michael
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- Synthesis of N-α-pyridylmethyl amino alcohols and application in catalytic asymmetric addition of diethylzinc to aromatic aldehydes
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A series of novel chiral ligands 2a-2f were conveniently prepared from β-amino alcohols through a two-step reaction and applied to catalyze the enantioselective addition of diethylzinc to benzaldehyde. Among them, ligand 2c was found to show the best asym
- Wu, Yangjie,Yun, Hongying,Wu, Yusheng,Ding, Kuiling,Zhou, Ying
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- Engineering catalysts for enantioselective addition of diethylzinc to aldehydes with racemic amino alcohols: Nonlinear effects in asymmetric deactivation of racemic catalysts
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Correct additions make a difference: Asymmetric deactivation and asymmetric amplification concepts coupled with a high-throughput screening technique provided a successful strategy for designing a highly enantioselective catalytic system by simple combination of a racemic amino alcohol (rac-DB) and a nonracemic additive (AA). The example in the scheme shows the conversion of 1 into 2 with up to 92.7% ee.
- Long, Jiang,Ding, Kuiling
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- A catalytic and mechanistic investigation of optically active helical poly[3-(9-alkylfluoren-9-yl)propylene oxide]s in the enantioselective addition of ethylmagnesium bromide to aldehydes
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Optically active helical poly[(S)-3-(9-alkylfluoren-9-yl)propylene oxide]s (poly-(S)-AFPOs) without additional stereogenic units were used to induce the enantioselective addition of ethylmagnesium bromide to aldehydes, giving up to 53% ee of the products.
- Zhang, Anlin,Yang, Nianfa,Yang, Liwen,Peng, Dan
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- A facile synthesis and the asymmetric catalytic activity of BINOL-based thiazole (thiadiazole) thioether ligands
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Four new BINOL-based thiazole (thiadiazole) thioether ligands (S)-1, (S)-2, (S,S)-3 and (S)-4 were prepared. When their catalytic effectiveness was tested, good results (up to 93% ee and 97% yield) were obtained in the asymmetric addition of diethylzinc to aldehydes while poor results were obtained in the asymmetric conjugate addition of diethylzinc to enones.
- Dong, Zhi-Bing,Liu, Bing,Fang, Cao,Li, Jin-Shan
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- Synthesis of the novel chiral 1,3-amino alcohol 8-N,N-bis(ferrocenylmethyl)amino-menthol and its use as catalyst in the enantioselective addition of diethylzinc to aldehydes
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Optically active 8-N,N-bis(ferrocenylmethyl)aminomenthol 5, obtained by condensation of (-)-aminomenthol with ferrocenecarboxaldehyde followed by N-alkylation with (ferrocenylmethyl)trimethylammonium iodide and further reduction, was found to catalyze (5 mol%) the enantioselective ethylation of aromatic, aliphatic and organometallic aldehydes to secondary alcohols with high enantioselectivities (up to 95%) at room temperature.
- Vilaplana, Maria J.,Molina, Pedro,Arques, Antonio,Andres, Celia,Pedrosa, Rafael
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- The synthesis of N,O-ferrocenyl pyrrolidine-containing ligands and their application in the diethyl- and diphenylzinc addition to aromatic aldehydes
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(Chemical Equation Presented) A facile route to a series of planar chiral N,O-ferrocenyl pyrrolidine-containing ligands with varying substituents at the nitrogen and oxygen donor atoms is described. The oxygen donor atom was introduced via a diastereoselective ortho-metalation of N-methylpyrrolidinyl and N-allylpyrrolidinyl ferrocene intermediates and was quenched with various ketones. The nitrogen substituent was varied through deallylation and subsequent derivatization of a secondary pyrrolidine. The efficacy of these novel ligands was investigated in the enantioselective addition of diethylzinc and diphenylzinc to aromatic aldehydes. The ligands proved highly effective in the diethylzinc addition to benzaldehyde that resulted in high yields of up to 99% and enantioselectivities (ee's) of up to 95%. The role of planar chirality was explored and the results indicated that the planar chirality, and not the central chirality, of the ferrocenyl ligands was the dominant stereo-controlling element. Employment of a mixed ethyl-phenylzinc reagent in the phenylation of aromatic aldehydes led to a mixture of the two additional products, and the phenylated product was obtained in up to 37% ee.
- Ahern, Theresa,Mueller-Bunz, Helge,Guiry, Patrick J.
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- Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by Chiral Titanate Complexes with a Tetradentate Ligand
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Enantioselective alkylation of aldehydes with Et2Zn has been studied.This catalytic system employs titanate complexes with a tetradentate helical ligand to facilitate the transformation.
- Zhang, Xumu,Guo, Cheng
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- New chiral ferrocenyloxazolines: The first planar chiral triferrocenylmethane derivative and its use in asymmetric catalysis
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New planar chiral enantiopure ferrocenyloxazolines have been prepared including ferrocenyldiphenylmethanol, diferrocenylphenylmethanol and triferrocenylmethanol derivatives (S,pR)-10 - (S,pR)-12, the latter being the first chiral triferrocenylmethanol der
- Garabatos-Perera, José Ramon,Butensch?n, Holger
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- Polystyrene-supported (R)-2-piperazino-1,1,2-triphenylethanol: A readily available supported ligand with unparalleled catalytic activity and enantioselectivity
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(Chemical Equation Presented) A very active and highly enantioselective catalytic resin, designed for minimal perturbation of the catalytic center by the polymer matrix, has been assembled in two steps from (S)-triphenylethylene oxide, piperazine, and Merrifield resin and tested in the enantioselective ethylation of aldehydes. 1-Arylpropanols of 94-95% ee are obtained in high yield by the use of only 2 mol % of catalytic resin at 0°C for 4 h.
- Castellnou, David,Sola, Lluis,Jimeno, Ciril,Fraile, Jose M.,Mayoral, Jose A.,Riera, Antoni,Pericas, Miquel A.
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- Synthetic, structural, NMR and catalytic studies of phosphinic amide-phosphoryl chalcogenides (chalcogen = O, S, Se) as mixed-donor bidentate ligands in zinc chemistry
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ortho Substituted (diphenylphosphoryl)-, (diphenylphosphorothioyl)- and (diphenylphosphoroselenoyl)-phosphinic amides o-C6H 4(P(X)Ph2)(P(O)NiPr2) (X = O (20a), S (20b), Se (20c)) were synthesized by ortho directed lithiation of N,N-diisopropyl-P,P-diphenylphosphinic amide (Ph2P(O)N iPr2) followed by trapping with Ph2PCl and subsequent oxidation of the o-(diphenylphosphine)phosphinic amide (19) with H2O2, S8 and Se. The reaction of the new mixed-donor bidentate ligands with zinc dichloride afforded the corresponding complexes [ZnCl2(P(X)Ph2)o-C6H 4(P(O)NiPr2)] (21a-c). The new compounds were structurally characterized in solution by nuclear magnetic resonance spectroscopy and in the solid-state by X-ray diffraction analysis of the ligand (20b) and the three complexes (21a-c). The X-ray crystal structure of 20b suggests the existence of a PO→P(S)-C intramolecular nonbonded interaction. The natural bond orbital (NBO) analysis using DFT methods showed that the stabilization effect provided by a nO→σ* P-C orbital interaction was negligible. The molecular structure of the complexes consisted of seven-membered chelates formed by O,X-coordination of the ligands to the zinc cation. The metal is four-coordinated by binding to the two chlorine atoms showing a distorted tetrahedral geometry. Applications in catalysis revealed that hemilabile ligands 20a-c act as significant promoters of the addition of diethylzinc to aldehydes, with 20a showing the highest activity. Chelation of Et2Zn with 20a was evidenced by NMR spectroscopy.
- Del Aguila-Sanchez, Miguel A.,Santos-Bastos, Neidemar M.,Ramalho-Freitas, Maria C.,Garcia Lopez, Jesus,Costa De Souza, Marcos,Camargos-Resende, Jackson A. L.,Casimiro, Maria,Alves-Romeiro, Gilberto,Iglesias, Maria Jose,Lopez Ortiz, Fernando
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- Chiral ferrocenyl amino alcohols for enantioselective additions of diethylzinc to aldehydes
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Optically active ferrocenyl amino alcohols have been prepared from commercially available L-alaninol, L-leucinol and L-valinol. They have been utilized as chiral ligands in the catalytic addition of diethylzinc to aldehydes. The influence of the substitue
- Bastin, Stephanie,Ginj, Mihaela,Brocard, Jacques,Pelinski, Lydie,Novogrocki, Guy
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- On the role of planar chirality in asymmetric catalysis: Improvement of enantioselectivity in the addition of diethylzinc to aldehydes with planar chiral 1,1′-N,O-ferrocenyl ligands
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A series of novel planar chiral 1,1′-N,O-ferrocenyl ligands have been synthesized, and applied as catalysts in asymmetric diethylzinc additions to aldehydes. The results indicate that the planar chirality had great impact on the reaction outcome.
- Li, Ming,Yuan, Ke,Li, Yang-Yang,Cao, Bo-Xun,Sun, Jie,Hou, Xue-Long
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- The synthesis of a novel non-C2 symmetric H4-BINOL ligand and its application to titanium-catalyzed enantioselective addition of diethylzinc to aldehydes
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The synthesis of the novel non-C2 symmetric ligand (R)-5,6,7,8-tetrahydro-1,1'-binaphthol has been achieved via partial reduction of 2,2'-bis(methoxymethoxy)-1,1'-binaphthyl with Raney Ni-Al alloy in dilute aqueous NaOH solution followed by hyd
- Shen, Xiaoqiang,Guo, Hui,Ding, Kuiling
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- (1S,2R,3R,4R)-α,α,α',α'-tetraphenylbicyclo[2.2.1]heptane-2 ,3-dimet hanol and its enantiomer as ligands in titanate-complex-catalyzed diethylzinc addition to aldehydes
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Starting from (1S,2R,3R,4R)-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid (1) and its enantiomer ent-1 the title compounds 3 and ent-3 were synthesized in 74% yield. They were used in asymmetric synthesis for the first time. The titanate-complex-catalyzed a
- Dreisbach,Kragl,Wandrey
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- Enantioselective alkylation of aldehydes catalyzed by a highly active titanium complex of 3-substituted unsymmetric BINOL
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A titanium complex derived from 3-(3,5-diphenylphenyl)-BINOL exhibits an enhanced catalytic activity in the asymmetric alkylation of aldehydes, allowing the reduction of the catalyst amount to less than 1 mol % without deterioration in enantioselectivity.
- Harada, Toshiro,Kanda, Kousou
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- Asymmetric diethylzinc addition and phenyl transfer to aldehydes using chiral cis-cyclopropane-based amino alcohols
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A new series of amino alcohols with a chiral cyclopropane backbone have been developed and used in the catalytic asymmetric diethylzinc addition and phenyl transfer to various types of aldehydes. These cyclopropane-based chiral amino alcohols show high enantioselectivity in the addition of organozincs to aromatic and aliphatic aldehydes. For diethylzinc addition to aromatic and aliphatic aldehydes, up to 97% ee and 93% ee are obtained, respectively. For the phenyl transfer to aromatic aldehydes, the best enantioselectivity was 89% ee.
- Zhong, Jiangchun,Guo, Hongchao,Wang, Mingan,Yin, Mingming,Wang, Min
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- A practical o-hydroxybenzylamines promoted enantioselective addition of dialkylzincs to aldehydes with asymmetric amplification
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The addition of dialkylzincs to aldehydes is accelerated considerably by the presence of a catalytic amount of o-hydroxybenzylamine (R,R)-2e to give, after hydrolysis, the corresponding alcohol (S)-9 in good enantiomeric purity. The origins of the enantioselection have been elucidated. A strong positive nonlinear relationship was observed for the reaction enantioselctivity with the use of o-hydroxybenzylamine 2e, which is very accessible through a short stereoselective synthetic route. The enantiomeric purity of the product 9 is much higher than the d.e. of the chiral source 2e, and the rate of the enantioselective catalysis increases considerably with the increase of the d.e. of (R,R)-2e. Copyright (C) 2000 Elsevier Science Ltd.
- Palmieri, Gianni
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- Novel thiazolidine derivatives as chiral catalysts in the enantioselective addition of diethylzinc to aldehydes
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New chiral thiazolidine derivatives were synthesized conveniently from natural L-cysteine and showed good enantioselectivity (up to 90% ee) in the addition of diethylzinc to aldehydes. The catalytic efficiency of the thiazolidine derivatives is influenced by the different structures of the thiazolidine rings and the bulkiness of R moiety in the ester groups. (C) 2000 Elsevier Science Ltd.
- Meng, Qinglin,Li, Yuelan,He, Yan,Guan, Yedi
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- Asymmetric catalytic alkylation of aldehydes with diethylzinc using a chiral binaphthol-titanium complex
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The asymmetric catalytic alkylation of aldehydes with diethylzinc using (R)- BINOL-Ti(O-i-Pr)2 complex as an asymmetric precatalyst is shown to afford the corresponding secondary alcohols in a high enantioselectivity (up to 86% ee).
- Mori, Maki,Nakai, Takeshi
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- 1,1′-Binaphthylazepine-based ligands for asymmetric catalysis. Part 2: New aminoalcohols as chiral ligands in the enantioselective addition of ZnEt2 to aromatic aldehydes
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The new enantiopure 1,2-aminoalcohols 1b-1h having 1,1′-binaphthylazepine skeleton have been tested as catalytic precursors in the enantioselective addition of ZnEt2 to benzaldehyde. The best results were seen with ligand 1d, which owes its chi
- Superchi, Stefano,Mecca, Tommaso,Giorgio, Egidio,Rosini, Carlo
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- Enantioselective addition of diethylzinc to aldehydes using 1,1′-bi-2-naphthol-3,3′-dicarboxamide as a chiral auxiliary
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A highly enantioselective addition of diethylzinc to a wide range of aldehydes was achieved by using N,N,N′,N′-tetraalkyl-1,1′-bi-2-naphthol-3,3′- dicarboxamides as chiral auxiliaries.
- Kitajima, Hiroshi,Ito, Katsuji,Katsuki, Tsutomu
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by (1R,2R)-10-(dialkylamino)isoborneols
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(1R,2R)-10-Dialkylammoisoborneols, γ-amino alcohol-type ligands, were synthesized from (+)-ketopinic acid. Their catalytic ability as a chiral ligand for enantioselective addition of diethylzinc to aldehydes was evaluated. Among them, the ligand with a 9-
- Hari, Yoshiyuki,Aoyama, Toyohiko
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- Practical and highly enantioselective alkylation of aldehydes catalyzed by a titanium complex of 3-aryl H8-BINOL
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A titanium complex derived from 3-(3,5-diphenylphenyl)-H8-BINOL exhibits high catalytic activity and enantioselectivity in the alkylation of aldehydes. Enantioselectivities comparable to or higher than 20 mol % of the parent H8-BINOL
- Harada, Toshiro,Ukon, Takahiro
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- Chiral 2-(1-dimethylaminoethyl)ferrocenecarbaldehyde as an effective catalyst for asymmetric alkylation of aldehydes with dialkylzinc
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The chiral ferrocenecarbaldehyde bearing an amino group was used as a ligand of diethylzinc in the asymmetric alkylation of aldehydes. It effectively catalyzed the reaction with either aromatic, straight chain or branched aliphatic aldehydes to afford chi
- Fukuzawa, Shin-Ichi,Kato, Hirohisa
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- Chiral thiazolidines in the enantioselective ethylation of aldehydes: An experimental and computational study
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A library of new chiral thiazolidines was prepared starting from L-cysteine and D-penicillamine in a simple, one-step procedure. 2-Arylthiazolidines were obtained, as diastereoisomeric mixtures, with good yields and in short reaction times, through a new and greener procedure, using microwave irradiation. Their use as chiral ligands in the enantioselective ethylation of aromatic aldehydes was studied and optimized, originating good to excellent conversions and ee up to 94% in 6 h. A series of heteroaromatic and aliphatic substrates were also enantioselectively ethylated with success, with ee up to 77%. The distinct opposite chirality in L-cysteine and D-penicillamine makes the use of these ligands an interesting approach for obtaining both the (S) and (R) enantiomers of the chiral alcohols, compounds with potential applications in the area of fine chemistry. NMR studies were carried out using a diastereoisomeric mixture of thiazolidines, allowing the identification of the most stable structure. Computational studies confirmed this result and also gave important insight into the species involved in the catalytic cycle of the enantioselective alkylation.
- Tavares, Nélia C.T.,Neves, César T.,Milne, Bruce F.,Murtinho, Dina,Pais, Alberto A.C.C.,Serra, M. Elisa Silva
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- Synthesis of C2-symmetrical bis-β-amino alcohols and their application in the enantioselective addition of diethylzinc to aldehydes
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The C2-symmetrical bis-β-amino alcohols 1-6 were prepared and especially attention is focused on bridges, which link the two β-amino alcohol units. These ligands have been applied as chiral catalysts in the asymmetric addition of diethylzinc to aldehydes. sec-Alcohols have been obtained in good yields with up to 95.4% enantiomeric excess.
- Xu, Qianyong,Wang, Hui,Pan, Xinfu,Chan, Albert S.C,Yang, Teng-Kuei
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- Catalytic asymmetric alkylation of aldehydes by using trialkylboranes
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Triethylborane can be used in the asymmetric alkylation of aldehydes by using a 3-(3,5-diphenylphenyl)-H8-BINOL-derived titanium(IV) catalyst in the presence of an excess amount of titanium tetraisopropoxide. The reaction proceeds with a low catalyst loading (2 mol-%), exhibiting high enantioselectivity for aromatic and unsaturated aldehydes. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Ukon, Takahiro,Harada, Toshiro
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- Modular amino acid amide chiral ligands for enantioselective addition of diethylzinc to aromatic aldehydes
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Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acid amide chiral ligand (2S)-3-phenyl-N-((R)-1-phenyl-ethyl)-2-(tosylamino)propanamide without using titanium complex. The catalytic system employing 10 mol% of 1g was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron-donating and electron-withdrawing substituents, giving up to 82% ee of the corresponding secondary alcohol under mild conditions.
- Gou, Shaohua,Ye, Zhongbin,Chang, Jing,Gou, Guangjun,Feng, Mingming
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- Chiral ligands containing heteroatoms. 8. 2-[(2s)-2-Pyrrolidinyl]pyridine as a novel catalyst in the enantioselective addition of diethylzinc to aldehydes
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The title compound has been demonstrated to be an effective enantioselective catalyst in the addition of diethyizinc to aldehydes: optically active secondary alcohols in up to 100% ee were obtained in high yields. The temperature dependence of the stercod
- Chelucci, Giorgio,Conti, Sandra,Falorni, Massimo,Giacomelli, Giampaolo
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- A new Ferrocene in the Asymmetric Addition of Diethylzinc to Aldehydes
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The use of a new ferrocene in the asymmetric addition of diethylzinc to aldehydes is reported. Secondary alcohols with enantioselectivities of up to 95% ee are obtained.
- Bolm, Carsten,Mu?iz Fernández, Kilian,Seger, Andreas,Raabe, Gerhard
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- Chiral diphenylselenophosphoramides: A new class of chiral ligands for the titanium(IV) alkoxide-promoted addition of diethylzinc to aldehydes
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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. Ano
- Shi, Min,Sui, Wen-Sheng
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- Design of novel chiral N,N,O-tridentate phenanthroline ligands and their application to enantioselective addition of organozinc reagents to aldehydes
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The novel N,N,O-tridentate phenanthroline ligand (BinThro) bearing an axially chiral binaphthyl backbone prepared from BINOL was found to be an effective chiral catalyst for enantioselective addition of diethylzinc to aromatic aldehydes with high enantios
- Naganawa, Yuki,Namba, Tomoya,Aoyama, Tomotaka,Shoji, Kentaro,Nishiyama, Hisao
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- The effect of direct steric interaction between substrate substituents and ligand substituents on enantioselectivities in asymmetric addition of diethylzinc to aldehydes catalyzed by sterically congested ferrocenyl aziridino alcohols
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The direct strong steric interaction between substrate substituents and ligand substituents was first discovered in asymmetric addition of diethylzinc to aldehydes catalyzed by sterically congested ferrocenyl aziridino alcohol derivatives. In addition, th
- Wang, Min-Can,Hou, Xue-Hui,Chi, Chao-Xian,Tang, Ming-Sheng
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- A novel trinuclear titanium(IV) complex with a C3 axis along Ti1-Ti2-Ti3 containing 3-[(1H-1,2,4-triazol-1-yl)methyl]-BINOLate ligands: synthesis, structure, and reactivity
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A new modified BINOL, (S)-3-[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-binaphthol, was prepared. In the presence of titanium tetraisopropoxide, this ligand showed moderate catalytic properties for the asymmetric addition of diethylzinc to aldehydes. By treating rac-3-[(1H-1,2,4-triazol-1-yl)methyl]-1,1′-binaphthol with excess titanium tetraisopropoxide, a novel trinuclear titanium(IV) complex was obtained. A C3 axis along Ti1-Ti2-Ti3 is present in the molecule.
- Liu, Bing,Jiang, Fu-Yong,Song, Hai-Bin,Li, Jin-Shan
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- Catalytic enantioselective addition of diethylzinc to aldehydes: Synthesis and application of a new cyclic catalyst
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The new optically active b-amino alcohol (S)-1-methyl-2-(diphenylhydroxymethyl)azetidine (S)-4 derived from (S)-azetidinecarboxylic acid (S)-1 catalyzes the enantioselective addition of diethylzinc to various aldehydes. The resulting chiral secondary alco
- Behnen,Mehler,Martens
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- The synthesis of new optically active 2-methylquinoline derivatives and their application in the enantioselective addition of diethylzinc to aldehydes
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Homochiral 2-methylquinoline derivatives have been synthesized and applied in the enantioselective addition of diethylzinc to aldehydes. Good yields and enantiomeric excesses of up to 91.4% were observed in these reactions.
- Xu, Qianyong,Wang, Guoxing,Pan, Xinfu,Chan, Albert S.C.
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- Modular ligands derived from amino acids for the enantio selective addition of organozinc reagents to aldehydes
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A new series of modular chiral ligands that are derived from amino acids were prepared and tested for their ability to catalyze the asymmetric addition of alkylzinc reagents to aromatic and aliphatic aldehydes. The ligands contain a tertiary amine, an amino acid side chain, and a carbamate or amide functional group. One ligand, which was synthesized from Ile, catalyzes the addition of diethylzinc to cyclohexanecarboxaldehyde in 99% ee.
- Richmond, Meaghan L.,Seto, Christopher T.
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- Novel C2-symmetric 1,1′-disubstituted ferrocenyl aziridino alcohol ligands: Remarkable improvement of enantioselectivity in the catalytic asymmetric addition of diethylzinc to aldehydes
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A series of novel chiral C2-symmetric 1,1′-disubstituted ferrocenyl aziridino alcohols have been readily synthesized and applied as catalysts to promote enantioselective addition of diethylzinc to aldehydes affording the corresponding 1-propano
- Wang, Min-Can,Hou, Xue-Hui,Xu, Cui-Lian,Liu, Lan-Tao,Li, Gui-Lan,Wang, De-Kun
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- Highly enantio- and diastereoselective tandem generation of cyclopropyl alcohols with up to four contiguous stereocenters
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Three highly enantio- and diastereoselective one-pot procedures for the synthesis of cyclopropyl and iodocyclopropyl alcohols with up to four contiguous stereocenters are reported. Route 1 involves asymmetric addition of an alkylzinc reagent to an enal fo
- Kim, Hun Young,Lurain, Alice E.,Garcia-Garcia, Patricia,Carroll, Patrick J.,Walsh, Patrick J.
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- 2,2′-Bipyridine-α,α′-trifluoromethyl-diol ligand: Synthesis and application in the asymmetric Et2Zn alkylation of aldehydes
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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
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supporting information
p. 11025 - 11028
(2021/11/03)
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- Cobalt-Catalyzed Enantiospecific Dynamic Kinetic Cross-Electrophile Vinylation of Allylic Alcohols with Vinyl Triflates
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Asymmetric cross-electrophile coupling has emerged as a promising tool for producing chiral molecules; however, the potential of this chemistry with metals other than nickel remains unknown. Herein, we report a cobalt-catalyzed enantiospecific vinylation
- Han, Guan-Yu,Kang, Shaolin,Liu, Xue-Yuan,Ma, Wei-Yuan,Pang, Xiaobo,Shu, Xing-Zhong
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supporting information
p. 15930 - 15935
(2021/10/20)
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- A Heck reaction/photochemical alkene isomerization sequence to prepare functionalized quinolines
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A route to prepare functionalized quinolines based on a Heck reaction/UV-induced alkene isomerization sequence is described. The method allows for the preparation of quinolines under mild and neutral conditions and has broad functional group tolerance. Acid-sensitive functional groups that would not be tolerated under previous approaches can be included and a one-pot quinoline forming procedure is also reported.
- Donohoe, Timothy J.,Hoff, Oskar,Hoffman, Jack B.,Kelly, Alex,Walker, Johannes C. L.,Werrel, Simon
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- Asymmetric transfer hydrogenation of cycloalkyl vinyl ketones to allylic alcohols catalyzed by ruthenium amido complexes
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A chemoselective 1,2-reduction of cycloalkyl vinyl ketones via asymmetric transfer hydrogenation is described. The reduction proceeded smoothly with a chiral diamine ruthenium complex as a catalyst and a HCOOH-NEt3 azeotrope as both a hydrogen source and solvent under mild conditions. A wide range of 1-cycloalkyl chiral allylic alcohols were obtained in good yields and up to 87% ee. It was found that the alkyl group plays an important role in the enantioselectivity.
- Liu, Sensheng,Cui, Peng,Wang, Juan,Zhou, Haifeng,Liu, Qixing,Lv, Jinliang
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supporting information
p. 264 - 267
(2019/01/10)
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- Synthesis of Allylsilanes via Nickel-Catalyzed Cross-Coupling of Silicon Nucleophiles with Allyl Alcohols
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NiCl2(PMe3)2-catalyzed reaction of allyl alcohols with silylzinc reagents, including PhMe2SiZnCl, Ph2MeSiZnCl, and Ph3SiZnCl, was performed, achieving allylsilanes in high yields. Aryl- and heteroaryl-substituted allyl alcohols, (E)-3-arylprop-2-en-1-ols, 1-aryl-prop-2-en-1-ols, and (E)-1-phenylpent-1-en-3-ol can be employed in the transformation. A range of functional groups as well as heteroaryl groups were tolerated. Reaction exhibited high regioselectivity and E/Z-selectivity when 1- or 3-aryl-substituted allyl alcohols were used as the substrates. Reaction of chiral allyl alcohol, (S,E)-1-phenylpent-1-en-3-ol, yielded a configuration-inversion product (R,E)-dimethyl(phenyl)(1-phenylpent-1-en-3-yl)silane.
- Yang, Bo,Wang, Zhong-Xia
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supporting information
p. 7965 - 7969
(2019/10/19)
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- Axially chiral tridentate isoquinoline derived ligands for diethylzinc addition to aldehydes
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The synthesis and resolution of new tridentate isoquinoline-derived ligands has been developed. The key steps in the synthetic sequence include successive, chemo-selective Suzuki-Miyaura cross-couplings of 1,3-dichloroisoquinoline with suitable arylboronic acids. The new ligands prepared in this manner were resolved either via molecular complexation with N-benzylcinchonidinium chloride as with 1-[3-(2-hydroxyphenyl)isoquinolin-1-yl]naphthalen-2-ol or via chromatographic separation of its epimeric camphorsulfonates as for 1,3-bis-(2-hydroxynaphthalen-1-yl)isoquinoline. 4-tert-Butyl-2-chloro-6-[1-(2-hydroxymethylnaphthalen-1-yl)isoquinolin-3-yl]phenol was resolved by chiral semi-preparative HPLC. The application of these ligands in the diethylzinc addition to aldehydes was investigated. In certain cases, the desired secondary alcohols were obtained in high yield with excellent enantiomeric excess (ee > 99%) at low catalyst loading (1 mol%).
- Sweetman, Brian A.,Guiry, Patrick J.
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p. 5567 - 5581
(2018/08/09)
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- New C2-symmetric six-membered carbene ligands for asymmetric diethylzinc addition of arylaldehydes
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A series of new six-membered NHC precursors were prepared by simply esterification of their parent compounds. Their applicability in asymmetric diethylzinc addition of arylaldehydes has been demonstrated and the corresponding secondary alcohol was obtained with good yields and moderate enantioselectivities. (Figure pressented)
- Zhou, Bihui,Li, Zijing,Yang, Chen,Li, Linlin,Fan, Limei,Huang, Hongxia,Li, Jie
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- Br?nsted Acid Enabled Nickel-Catalyzed Hydroalkenylation of Aldehydes with Styrene and its Derivatives
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A Br?nsted acid enabled nickel-catalyzed hydroalkenylation of aldehydes and styrene derivatives has been developed. The Br?nsted acid acts as a proton shuttle to transfer a proton from the alkene to the aldehyde, thereby leading to an economical and byproduct-free coupling. A series of synthetically useful allylic alcohols were obtained through one-step reactions from readily available styrene derivatives and aliphatic aldehydes in up to 88 % yield and with high linear selectivity.
- Han, Xing-Wang,Zhang, Tao,Zheng, Yan-Long,Yao, Wei-Wei,Li, Jiang-Fei,Pu, You-Ge,Ye, Mengchun,Zhou, Qi-Lin
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supporting information
p. 5068 - 5071
(2018/03/27)
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- Enantioselective alkylation of aromatic aldehydes with (+)-camphoric acid derived chiral 1,3-diamine ligands
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A series of chiral 1,3-diamine ligands derived from (+)-camphoric acid were prepared from the reaction of 1,3-diamino-1,2,2-trimethylcyclopentane with aromatic aldehydes, followed by reduction of the corresponding diimines. These newly synthesized ligands
- Serra, M. Elisa Silva,Murtinho, Dina,Paz, Victória
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p. 381 - 386
(2017/02/18)
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- Synthesis of Chiral α,β-Unsaturated γ-Amino Esters via Pd-Catalyzed Asymmetric Allylic Amination
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A Pd-catalyzed asymmetric allylic amination of 4-substituted 2-acetoxybut-3-enoates with amines has been developed for the regiospecific synthesis of chiral α,β-unsaturated γ-amino esters. The desired chiral aminated products can be obtained in up to 98%
- Xia, Chao,Shen, Jiefeng,Liu, Delong,Zhang, Wanbin
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supporting information
p. 4251 - 4254
(2017/08/23)
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- Accessing Both Retention and Inversion Pathways in Stereospecific, Nickel-Catalyzed Miyaura Borylations of Allylic Pivalates
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We have developed a stereospecific, nickel-catalyzed Miyaura borylation of allylic pivalates, which delivers highly enantioenriched α-stereogenic γ-aryl allylboronates with good yields and regioselectivities. Our complementary sets of conditions enable access to either enantiomer of allylboronate product from a single enantiomer of readily prepared allylic pivalate substrate. Excellent functional group tolerance, yields, regioselectivities, and stereochemical fidelities are observed. The stereochemical switch from stereoretention to stereoinversion largely depends upon solvent and can be explained by competitive pathways for the oxidative addition step. Our mechanistic investigations support a stereoretentive pathway stemming from a directed oxidative addition and a stereoinvertive pathway that is dominant when MeCN blocks coordination of the directing group by binding the nickel catalyst.
- Zhou, Qi,Srinivas, Harathi D.,Zhang, Songnan,Watson, Mary P.
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supporting information
p. 11989 - 11995
(2016/10/07)
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- Homochiral 2D Porous Covalent Organic Frameworks for Heterogeneous Asymmetric Catalysis
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There have been breakthroughs in the development of covalent organic frameworks (COFs) with tunability of composition, structure, and function, but the synthesis of chiral COFs remains a great challenge. Here we report the construction of two-dimensional
- Wang, Xiuren,Han, Xing,Zhang, Jie,Wu, Xiaowei,Liu, Yan,Cui, Yong
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supporting information
p. 12332 - 12335
(2016/10/07)
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- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
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β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C-C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.
- Goncalves-Contal, Sylvie,Gremaud, Ludovic,Palais, La?titia,Babel, Lucille,Alexakis, Alexandre
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p. 3301 - 3308
(2016/09/12)
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- Enantioselective addition of organozinc reagents to carbonyl compounds catalyzed by a camphor derived chiral γ-amino thiol ligand
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In this article, the design and synthesis of the chiral camphor derived γ-amino thiol ligand 17 and its application in catalytic enantioselective carbon-carbon forming reactions through the addition of organozinc reagents to carbonyl compounds is described. The catalytic activity and enantioselectivity of ligand 17 is demonstrated in the enantioselective addition of various organozinc reagents to aldehydes and ketoesters, offering the corresponding alcohols in high yields and enantioselectivities. The role of the mercapto group in the highly enantioselective 1,2-addition reaction of organozincs to aldehyde is also discussed.
- Wu, Hsyueh-Liang,Wu, Ping-Yu,Cheng, Ying-Ni,Uang, Biing-Jiun
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p. 2656 - 2665
(2016/05/10)
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- Electrophilic Cyanation of Boron Enolates: Efficient Access to Various β-Ketonitrile Derivatives
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The highly efficient electrophilic cyanation of boron enolates using readily available cyanating reagents, N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) and p-toluenesulfonyl cyanide (TsCN), is reported. Various β-ketonitriles were prepared by this new protocol, which has a remarkably broad substrate scope compared to existing methods. The present method also allowed efficient synthesis of β-ketonitriles containing a quaternary α-carbon center. In addition, a preliminary result with the use of a chiral boron enolate for the enantioselective cyanation reaction is described.
- Kiyokawa, Kensuke,Nagata, Takaya,Minakata, Satoshi
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p. 10458 - 10462
(2016/08/24)
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- Nazarov cyclization of divinyl ketones bearing an ester group at the β-position: A remarkable effect of α-substitution and alkene geometry on regioselectivity
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The Nazarov cyclization of divinyl ketones with an ester at the β-position was examined with particular reference to where the cyclic double bond forms. We observed unprecedented regioselectivity, dictated by the subtle substitution patterns at the α-position and alkene geometry of α,β and mostly, this selectivity is regardless of substitutions at α′- and β′-positions. The major implications of these observations are an aromatic group at the α-position with E-olefin geometry provides a cyclopentenone in which the double bond is not in conjugation with an ester, whereas Z-olefin provides a cyclopentenone in which the double bond is in conjugation with an ester; and divinyl ketones bearing an ester group at the β-position and an alkyl group at the α-position with E-olefin geometry provide a cyclopentenone in which the double bond is in conjugation with the ester.
- Sudhakar, Gangarajula,Raghavaiah, Jakka,Mahesh, Gaddam,Singarapu, Kiran Kumar
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supporting information
p. 2866 - 2872
(2016/03/12)
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- Synthesis of Ferrocene Oxazoline N,O ligands and Their Application in Asymmetric Ethyl- and Phenylzinc Additions to Aldehydes
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The synthesis of a range of novel gem-disubstituted ferrocene-oxazoline ligands and their application in both the asymmetric ethyl- and phenylzinc additions to aldehydes is reported. These studies reveal that gem-disubstitution of i-Pr-containing ferrocene oxazoline ligands results in increased enantioselectivity compared to their unsubstituted counterparts. Utilizing zinc catalysis, these ligands provided a wide range of secondary alcohols in yields of up to 93% with ee's of up to >99%. An interesting crystal structure of a ferrocene oxide-lithium tetramer showing lithium-nitrogen coordination in the solid state is also presented.
- Nottingham, Chris,Benson, Robert,Müller-Bunz, Helge,Guiry, Patrick J.
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p. 10163 - 10176
(2015/11/03)
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- Pincer-Nickel-Catalyzed Allyl-Aryl Coupling between Allyl Methyl Ethers and Arylzinc Chlorides
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The P,N,N-pincer nickel complex [Ni(Cl){N(2-Ph2PC6H4)(2′-Me2NC6H4)}]-catalyzed allyl-aryl coupling was studied. The reaction of allyl methyl ethers, including (1-methoxyallyl)arenes and (3-methoxyprop-1-en-1-yl)arenes, with arylzinc chlorides afforded linear (E)-alkenes in high yields, whereas the reaction of (E)-1-methoxytridec-2-ene with p-Me2NC6H4ZnCl generated a mixture of linear and branched alkenes.
- Tao, Jian-Long,Yang, Bo,Wang, Zhong-Xia
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p. 12627 - 12634
(2016/01/09)
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- Synthesis and structure-activity relationship study of substituted caffeate esters as antinociceptive agents modulating the TREK-1 channel
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The TWIK-related K+ channel, TREK-1, has recently emerged as an attractive therapeutic target for the development of a novel class of analgesic drugs. It has been reported that TREK-1 -/- mice were more sensitive than wild-type mice to painful stimuli, suggesting that activation of TREK-1 could result in pain inhibition. Here we report the synthesis of a series of substituted caffeate esters (12a-u) based on the hit compound CDC 2 (cinnamyl 3,4-dihydroxyl-α-cyanocinnamate). These analogs were evaluated for their ability to modulate TREK-1 channel by electrophysiology and for their in vivo antinociceptive activity (acetic acid induced-writhing assay) leading to the identification a series of novel molecules able to activate TREK-1 and displaying potent analgesic activity in vivo.
- Rodrigues, Nuno,Bennis, Khalil,Vivier, Delphine,Pereira, Vanessa,Chatelain, Franck C.,Chapuy, Eric,Deokar, Hemantkumar,Busserolles, Jér?me,Lesage, Florian,Eschalier, Alain,Ducki, Sylvie
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supporting information
p. 391 - 402
(2014/03/21)
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- The synthesis of chiral amino diol tridentate ligands and their enantioselective induction during the addition of diethylzinc to aldehydes
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A series of C2-symmetric chiral amino diol tridentate ligands 3a-g were prepared from achiral bulky organolithiums, achiral bulky primary amines, and optically active epichlorohydrin (ECH). The prepared C 2-symmetric chiral amino diol tridentate ligands were capable of inducing enantioselectivity in the model reaction of aromatic and aliphatic aldehydes with diethylzinc with an ee of up to 96%. The enantioselectivity can be modulated by adjusting the steric hindrance of the achiral reagents employed in the synthesis of the chiral ligand. The configuration of the addition product depended on the configuration of the amino diol ligands, which can be simply controlled as desired by using the ECH with the desired configuration during the preparation of the ligand.
- Zhang, An-Lin,Yang, Li-Wen,Yang, Nian-Fa,Liu, Yan-Ling
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p. 289 - 297
(2014/04/03)
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- 3-Aminoquinazolinones as chiral ligands in catalytic enantioselective diethylzinc and phenylacetylene addition to aldehydes
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A series of readily known enantiomerically pure 3-aminoquinazolinones 1a-d were synthesised from easily accessible chiral pool α-hydroxy acids and α-amino acids in only four steps without any requirement of chromatography. These quinazolinones were examined as chiral ligands for catalytic enantioselective diethylzinc and phenylacetylene additions to aldehydes. For enantioselective alkylations, the effects of temperature, solvent, diethylzinc and ligand criteria were analysed, and the desired chiral alcohols were obtained in up to 86% ee. 3-Aminoquinazolinones 1a-d were also shown to be very useful ligands in enantioselective alkynylations of aldehydes. Based upon the optimised conditions, the corresponding propargylic alcohols were obtained in up to 94% ee.
- Karabuga, Semistan,Karakaya, Idris,Ulukanli, Sabri
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p. 851 - 855
(2014/06/23)
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- Enantioselective oxidation of secondary alcohols by Candida parapsilosis ATCC 7330
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Optically pure allylic alcohols and 4-phenylbutan-2-ols were prepared by oxidative kinetic resolution using whole cells of Candida parapsilosis ATCC 7330. Only the 'S' enantiomer is selectively oxidized to the corresponding keto compound (yield, 37-46%) leaving the 'R' alcohol (yield, 37-52% and ee 46 to >99%). The biocatalytic method is carried out under mild conditions at 20°C, pH 6.5 in phosphate buffer.
- Sivakumari, Thakkellapati,Preetha, Radhakrishnan,Chadha, Anju
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p. 2257 - 2262
(2014/01/06)
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- PEG-supported recyclable catalyst for enantioselective ethylations
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A β-amino alcohol derived from 4-hydroxyproline was bound to polyethylene glycol (PEG) and used in the enantioselective ethylation of aryl aldehydes with diethyl zinc. Isolated yields of the corresponding alcohols ranged from 53 to 93% with ee's of 91-97%
- Zeng, Xiaofeng,Malik, Debasis,Chen, Ryan,Lee-Ruff, Edward
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p. 1168 - 1172
(2013/03/29)
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- Design, synthesis, and application of novel chiral ONN ligands for asymmetric alkylation
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Starting from easily available chiral pool amino alcohols, a set of novel chiral ONN ligands was synthesized and their catalytic potential was examined in asymmetric alkylation. Ligands with a secondary central NH group and N-methylated ONN ligands were successfully applied as catalysts in the addition of diethyl zinc to various aromatic aldehydes, yielding secondary alcohols in excellent yields of up to 99 % ee.
- Bica, Katharina,Leder, Sonja,Mereiter, Kurt,Gaertner, Peter
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p. 447 - 453
(2013/07/26)
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- Synthesis of 1,3-aminonaphthols by diastereoselective Betti-type aminoalkylation of dihydroxy naphthalenes; Diastereoselectivity, absolute configuration, and application
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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)
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- Asymmetric 1,2-reduction of enones with potassium borohydride catalyzed by chiral N,N′-dioxide-scandium(III) complexes
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The first catalytic enantioselective 1,2-reduction of enones with 0.45 mol equiv potassium borohydride solution catalyzed by a chiral N,N′-dioxide- Sc(III) complex catalyst was accomplished under mild reaction conditions. A number of optically active allylic alcohols were obtained in good to excellent enantioselectivities (up to 95% ee) with nearly quantitative yields.
- He, Peng,Liu, Xiaohua,Zheng, Haifeng,Li, Wei,Lin, Lili,Feng, Xiaoming
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supporting information
p. 5134 - 5137,4
(2020/09/15)
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- Polystyrene-supported (2S)-(-)-3-exo-piperazinoisoborneol: An efficient catalyst for the batch and continuous flow production of enantiopure alcohols
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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)
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- 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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- Synthesis of chiral pyridylphenols for the enantioselective addition of diethylzinc to aldehydes
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Chiral 8-substituted 2-(8,10,10-trimethyl-6-aza-tricyclo[7.1.1.0 2,7]undeca-2(7),3,5-trien-5-yl)-phenols were prepared from a high enantiopurity (>97% ee) of (1R)-(+)-α-pinene, and assessed in the enantioselective addition of diethylzinc to substituted benzaldehydes, giving the (S)-alcohols with enantiomeric excess ranging from 33% to 89%. Interestingly, in all cases, except for those of ortho-chlorobenzaldehyde, ortho- and para-methoxybenzaldehydes, the ee was >71%. The plot of the Hammett substitution constants vs. enantiomeric excess of the diethylzinc addition to either the ortho- or para-substituted benzaldehydes shows a linear correlation.
- Wu, Pei-Shan,Chen, Chinpiao
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experimental part
p. 768 - 781
(2012/08/27)
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- Synthetic approach toward cis-disubstituted γ- And δ-lactones through enantioselective dialkylzinc addition to aldehydes: Application to the synthesis of optically active flavors and fragrances
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A versatile and straightforward approach to optically active cis-4,5-disubstituted γ- and δ-lactones by catalytic enantioselective addition of dialkyzincs to cinnamic aldehydes and RCM ring closure has been reported. The synthetic importance of the enantioselective dialkylzinc alkylation of aldehydes has been thus widened. Such an approach has then been employed for the enantioselective synthesis of naturally occurring γ-lactone flavors like (S)-5-ethyl-butanolide (6a) and (4S,5S)-cis-whisky lactone (6b) and extended to the preparation of δ-lactones like (5S,6S)-5-methyl-6-ethylpentanolide (9a), precursor of the pheromone serricornin.
- Pisani, Laura,Superchi, Stefano,D'Elia, Alessandra,Scafato, Patrizia,Rosini, Carlo
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experimental part
p. 5779 - 5784
(2012/09/08)
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- The syntheses of new camphorsulfonylated ligands derived from 2-amino-2'-hydroxy-1,1'-binaphthyl and their enantioselectivities in the addition of dialkylzinc reagents to aldehydes
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A series of new camphorsulfonylated ligands derived from chiral 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN) and (+)-camphorsulfonic acid were synthesized by a short and simple synthetic sequence, and their enantioselective catalytic activities were assessed in the nucleophilic addition reaction of dialkylzinc reagents to aldehydes in the presence of titanium tetraisopropoxide. The most efficient ligand, N-hydroxycamphorsulfonylated (S)-NOBIN, gave (S)-addition products with good yields and up to 87% of ee value. The 1H nuclear magnetic resonance (NMR) and 13C NMR results of the titanium titration experiments on this ligand indicate that the most likely catalytic reactive species involved in this catalytic asymmetric addition is a bimetallic titanium complex. A possible catalytic reaction mechanism is proposed. Copyright
- Bian, Guangling,Huang, Huayin,Zong, Hua,Song, Ling
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p. 825 - 832
(2012/11/07)
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- C-X (X=Br, I) bond-tolerant aerobic oxidative cross-coupling: A strategy to selectively construct β-aryl ketones and aldehydes
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Using moelcular oxygen as the terminal oxidant, various aryl halide-containing β-aryl ketones and aldehydes can be synthesized directly from readily available allyic alcohols and boronic acids via palladium-catalyzed oxidative cross-coupling reactions. The dual roles of copper, including electron-carrier and Lewis acid functions, are supposed to be critical for the high reactivity and selectivity of this aerobic oxidative coupling transformation. Copyright
- Chen, Mao,Wang, Jie,Chai, Ziyi,You, Cai,Lei, Aiwen
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supporting information; scheme or table
p. 341 - 346
(2012/05/04)
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- CAMPHOR-DERIVED COMPOUNDS, METHOD FOR MANUFACTURING THE SAME, AND APPLICATION THEREOF
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Camphor-derived compounds are disclosed, which are represented as the following formula (I): wherein R1, R2, R3, and R4 each are defined as described in the specification. In addition, a method for manufacturing the camphor-derived compounds and application thereof are disclosed.
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Page/Page column 13; 15
(2012/04/05)
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- Phosphonium salt catalyzed addition of diethylzinc to aldehydes
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The addition of diethylzinc to aromatic, heteroaromatic, and aliphatic aldehydes at room temperature is efficiently catalyzed by 1-7 mol% tetrabutylphosphonium chloride. The corresponding addition products are obtained in good to excellent yields of up to 99%. Moreover, polymer bond phosphonium salts can be used to catalyze this reaction with excellent recovery of the polymer bond catalyst up to three cycles. The application of chiral bifunctional phosphonium salts revealed a remarkable counter anion effect. Changing the anion, the activity of the tetrabutylphosphonium salt decreased in the order Cl- > Br- > I- ≈ TsO- > BF4- ≈ PF6-. However, the nature of the cation had also significant influence. Tetraalkyl-ammonium chlorides showed similar activity compared to phosphonium chlorides, while alkaline metal chlorides proved to be considerably less active. Georg Thieme Verlag Stuttgart.
- Werner, Thomas,Riahi, Abdol Majid,Schramm, Heiko
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experimental part
p. 3482 - 3490
(2011/12/04)
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- Switching of enantioselectivity in the catalytic addition of diethylzinc to aldehydes by regioisomeric chiral 1,3-amino sulfonamide ligands
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Twenty chiral 1,3-amino sulfonamides of two classes (2a-i and 3a-k) have been prepared from (-)-cis-2-benzamidocyclohexanecarboxylic acid (1) and studied as ligands for catalytic enantioselective addition of Et2Zn to a variety of aromatic and aliphatic aldehydes. The ligands 2 and 3 are regioisomers in which the position of the amine and sulfonamide groups is exchanged. Each class of ligands with the same chirality was shown to afford sec-alcohols with the opposite stereochemistry. Structural surveys revealed that the combination of tertiary amino and p-toluenesufonylamido groups works most effectively for the reaction. Through optimization of the structural and reaction conditions, the best ligands quantitatively provided both enantiomeric secondary alcohols in good to excellent enantioselectivity of up to 94% and 98% ee for (S)- and (R)-enantiomers, respectively.
- Hirose, Takuji,Sugawara, Kazuyuki,Kodama, Koichi
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experimental part
p. 5413 - 5428
(2011/08/05)
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- Synthesis of novel 1,4-bissulfonamide ligands for enantioselective addition of diethylzinc to aldehydes
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Several novel chiral sulfonamide ligands based on (1R,2S,4R,5S)-1,4- diamino-2,5-dimethylcyclohexane skeleton have been synthesized and their application in the enantioselective addition of diethylzinc to aldehydes was investigated in the presence of Ti(O
- Yang, Minghua,Sun, Jiangtao,Zhu, Chengjian
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experimental part
p. 1697 - 1702
(2012/01/13)
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- Modular amino acids and β-amino alcohol-based chiral ligands for enantioselective addition of diethylzinc to aromatic aldehydes
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Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acids and ${bf beta}$-amino alcohol-based chiral ligand (2R)-N-[(1R,2S)-1-hydroxy-1-phenylpropan-2-yl]-3- phenyl-2-(tosylamino) propanamide (1f) without using titanium complex. The catalytic system employing 15 mol% of 1f was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron-donating and electron-withdrawing substituents, giving up to 97% ee of the corresponding secondary alcohol under mild conditions.
- Gou, Shaohua,Ye, Zhongbin,Gou, Guangjun,Feng, Mingming,Chang, Jing
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experimental part
p. 110 - 116
(2012/06/18)
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- Catalytic enantioselective β-alkylation of α,β-unsaturated aldehydes by combination of transition-metal- and aminocatalysis: Total synthesis of bisabolane sesquiterpenes
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Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol (see scheme). The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3- dehydrocurcumene and (S)-(+)-tumerone.
- Afewerki, Samson,Breistein, Palle,Pirttil?, Kristian,Deiana, Luca,Dziedzic, Pawel,Ibrahem, Ismail,C?rdova, Armando
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supporting information; experimental part
p. 8784 - 8788
(2011/09/15)
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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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- A systematic study of chiral homoprolinols and their derivatives in the catalysis of enantioselective addition of diethylzinc to aldehydes
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Homoprolinol analogs, a class of optically active γ-amino alcohols, were examined systematically in the enantioselective addition reactions of diethylzinc to aldehydes. By comparison of the results catalyzed by these γ-amino alcohols with those by the β-amino alcohols based on pyrrolidine architecture reported in the literature references, we have observed that the γ-amino alcohols are superior to the corresponding β-amino alcohols when the nitrogen and the oxygen are unsubstituted. Among the homoprolinols we tested, 2b gave the best results (45-88% yields, 44-81% ee) in the addition reactions. To the best of our knowledge, 2b has been noticed as one of the most efficient γ-amino alcohol catalysts based on pyrrolidine framework.
- Liu, Chang-Lu,Wei, Chang-Yong,Wang, Shi-Wen,Peng, Yun-Gui
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experimental part
p. 921 - 928
(2012/06/17)
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- Structure-based optimization of click-based histone deacetylase inhibitors
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Previously, we reported a click-chemistry based approach to the synthesis of a novel class of histone deacetylase (HDAC) inhibitors [1]. The lead compound NSC746457 was found to be as potent as SAHA (Vorinostat). Further optimization of NSC746457 by using
- Hou, Jingli,Feng, Congran,Li, Zhonghua,Fang, Qinghong,Wang, Huihui,Gu, Guoxian,Shi, Yikang,Liu, Pi,Xu, Feng,Yin, Zheng,Shen, Jie,Wang, Peng
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supporting information; experimental part
p. 3190 - 3200
(2011/07/29)
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