- Application of a Heterogeneous Chiral Titanium Catalyst Derived from Silica-Supported 3-Aryl H8-BINOL to Enantioselective Alkylation and Arylation of Aldehydes
-
A 3-aryl H8-BINOL was grafted on the surface of silica gel using a hydrosilane derivative as a precursor, and the resulting silica-supported ligand (6 mol %) was employed in the enantioselective alkylation and arylation of aldehydes in the pres
- Akai, Junichiro,Watanabe, Satoshi,Michikawa, Kumiko,Harada, Toshiro
-
-
Read Online
- Hydroxyalkyl thiazolines, a new class of highly efficient ligands for carbonyl additions
-
Hydroxyalkyl thiazoline ligands can easily be obtained in an isonitrile-based multicomponent reaction. These ligands are significantly more stable than the comparable oxazoline ligands, and give excellent enantiomeric excess in carbonyl additions of alkyl- and arylzinc compounds. Georg Thieme Verlag Stuttgart.
- Bauer, Michael,Maurer, Frauke,Hoffmann, Svenja M.,Kazmaier, Uli
-
-
Read Online
- Enantioselective additions of diphenylzinc to aldehydes using chiral pyrrolidinylmethanol derivatives as catalysts
-
The enantioselective addition of diphenylzinc to aldehydes using a series of chiral ligands derived from (S)-proline afforded secondary alcohols in high yields and with high enantiomeric excesses of up to 92.6%. The configuration of the secondary alcohol enantiomer obtained was found to be dependent on the catalyst used.
- Zhao, Gang,Li, Xiang-Guo,Wang, Xiu-Ran
-
-
Read Online
- Synthesis and electrochemical characterization of iminophosphine-based ruthenium(II) complexes and application in asymmetric transfer hydrogenation reaction as catalysts
-
A range of Ru(II) complexes have been prepared with chiral iminophosphine ligands ([(2-PPh2)C6H4CH=NCH(CH3)C6H5(4-R)]; R = –H, p-CH3, p-NO2) and characterized by 1H, 13C, 31P{1H} NMR and FTIR spectroscopy. The electrochemical properties of the [Ru(PN)2Cl2] complexes were investigated in ACN/TBAP solution with cyclic voltammetry and square wave voltammetry techniques. The use of chiral [Ru(PN)2Cl2] complexes as catalysts for the asymmetric transfer hydrogenation of aromatic and aliphatic ketones was studied in 2-propanol in an attempt to demonstrate the effect of substituents, which attached to the phenyl ring bonded to the nitrogen donor, on the catalytic activity and enantioselectivity. It was seen that the electronic effects of these substituents did not contribute to the catalytic efficiency of the ruthenium(II) catalysts.
- Kele?, Mustafa,Kele?, Hülya,Y?lmaz, Mustafa Kemal
-
-
Read Online
- Catalytic enantioselective aryl transfer to aldehydes using chiral 2,2'-bispyrrolidine-based salan ligands
-
Chiral C2-symmetric diamines have emerged as versatile auxiliaries or ligands in numerous asymmetric transformations. Chiral 2,2'-bispyrrolidine-based salan ligands were prepared and applied to the asymmetric aryl transfer to aldehydes with arylboronic acids as the source of transferable aryl groups. The corresponding diarylmethanols were obtained in high yields with moderate to good enantioselectivitives of up to 83% ee.
- Jia, Xuefeng,Lin, Aijun,Mao, Zhijie,Zhu, Chengjian,Cheng, Yixiang
-
-
Read Online
- Synthesis of rhodium(I) and iridium(I) complexes of chiral N-heterocyclic carbenes and their application to asymmetric transfer hydrogenation
-
Rhodium and iridium complexes of chiral NHC-phenolimine and NHC-amine ligands have been prepared and studied for asymmetric transfer hydrogenation. X-ray and NMR spectroscopy show that for NHC-phenolimine complexes abstraction of chloride results in a change in ligand coordination from NHC only to chelating NHC-imine. Complexes of NHC-amines are inactive for transfer hydrogenation, whereas complexes of NHC-phenolimines are active at room temperature for a range of aryl containing ketones. Enantioselectivity is very sensitive to the NHC N-substituent resulting in a switch in the predominant enantiomer.
- Dyson, Gavin,Frison, Jean-Cedric,Whitwood, Adrian C.,Douthwaite, Richard E.
-
-
Read Online
- Structural Insight into Enantioselective Inversion of an Alcohol Dehydrogenase Reveals a "polar Gate" in Stereorecognition of Diaryl Ketones
-
Diaryl ketones are important building blocks for synthesizing pharmaceuticals and are generally regarded as "difficult-to-reduce" ketones due to the large steric hindrance of their two bulky aromatic side chains. Alcohol dehydrogenase from Kluyveromyces polyspora (KpADH) has been identified as a robust biocatalyst due to its high conversion of diaryl ketone substrate (4-chlorophenyl)(pyridine-2-yl)ketone (CPMK) with a moderate R-selectivity of 82% ee. To modulate the stereoselectivity of KpADH, a "polarity scanning" strategy was proposed, in which six key residues inside and at the entrance of the substrate binding pocket were identified. After iterative combinatorial mutagenesis, variants Mu-R2 and Mu-S5 with enhanced (99.2% ee, R) and inverted (97.8% ee, S) stereoselectivity were obtained. The crystal structures of KpADH and two mutants in complex with NADPH were resolved to elucidate the evolution of enantioselective inversion. Based on MD simulation, Mu-R2-CPMKProR and Mu-S5-CPMKProS were more favorable in the formation of prereaction states. Interestingly, a quadrilateral plane formed by α-carbons of four residues (N136, V161, C237, and G214) was identified at the entrance of the substrate binding pocket of Mu-S5; this plane acts as a "polar gate" for substrates. Due to the discrepancy in charge characteristics between chlorophenyl and pyridine substituents, the pro-S orientation of CPMK is defined when it passes through the "polar gate" in Mu-S5, whereas the similar plane in wild-type is blocked by several aromatic residues. Our result paves the way for engineering stereocomplementary ADH toward bulky diaryl ketones and provides structural insight into the mechanism of stereoselective inversion.
- Zhou, Jieyu,Wang, Yue,Xu, Guochao,Wu, Lian,Han, Ruizhi,Schwaneberg, Ulrich,Rao, Yijian,Zhao, Yi-Lei,Zhou, Jiahai,Ni, Ye
-
-
Read Online
- Catalytic enantioselective aryl transfer: Asymmetric addition of diphenylzine to aldehydes
-
The asymmetric addition of diphenylzinc to aldehydes in the presence of catalytic amounts of a planar chiral ferrocene-based hydroxy oxazoline affords products with enantiomeric excesses of up to 96%.
- Bolm, Carsten,Muniz, Kilian
-
-
Read Online
- Chiral zinc amidate catalyzed additions of diethylzinc to aldehydes
-
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
-
-
Read Online
- Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups
-
A continuous flow system for the synthesis of enantioenriched diarylmethanols from aldehydes is described. The system uses an amino alcohol-functionalized polystyrene resin as the catalyst, and the arylating agent is conveniently prepared by transmetallation of triarylboroxins with diethylzinc.
- Rolland, Julien,Cambeiro, Xacobe C.,Rodriguez-Escrich, Carles,Pericas, Miquel A.
-
-
Read Online
- 2-Piperidino-1,1,2-triphenylethanol: A Highly Effective Catalyst for the Enantioselective Arylation of Aldehydes
-
Here we report the use of 2-piperidino-1,2,2-triphenylethanol (5) as an outstanding catalyst for the ligand-catalyzed arylation of aldehydes. The use of 5 and a 2/1 mixture of Et2Zn/Ph2Zn provided the corresponding chiral diarylcarbinols with enantiomeric excess of up to 99% ee. The effect of temperature on the reaction enantioselectivity was studied and the inversion temperature (Tinv) was determined to be 10 °C for reaction with p-tolylaldehyde. Most remarkably, lowering the amount of catalyst (5) to 0.5 mol % still afforded excellent levels of enantiocontrol (93.7% ee). Kinetics of the catalyzed and uncatalyzed arylation of aldehydes was studied by means of in situ FT-IR. The background uncatalyzed addition rates to p-tolylaldehyde when using pure Ph2Zn and Et2Zn/Ph 2-Zn (2/1) suggest that in the latter case a mixed zinc species forms (EtPhZn) minimizing the undesired nonselective addition. Formation of EtPhZn was modeled at the DFT calculation level. A four-center TS (TS-V) corresponding to the Et/Ph scrambling was localized along with two dimers (D-IV and D-VI). The model supports the hypothesis that Et/Ph exchange is a kinetically facile process. Gas evolution experiments during the formation of the active catalyst showed that the formation of an active site with a ONZn-Et (10) moiety is kinetically favored over ONZn-Ph (11). Finally, the phenyl transfer to benzaldehyde was modeled at the PM3(tm) level through anti and syn 5/4/4 tricyclic TS structures for both 10 and 11. The model could correctly predict the sense and selectivity of the overall process and predicted that 11 should be more selective than 10.
- Fontes, Montserrat,Verdaguer, Xavier,Sola, Lluis,Pericas, Miquel A.,Riera, Antoni
-
-
Read Online
- Instantaneous room-temperature and highly enantioselective ArTi(O-i-Pr)3 additions to aldehydes
-
Direct asymmetric additions of ArTi(O-i-Pr)3 to aldehydes catalyzed by a titanium catalyst of (R)-H8-BINOL are reported. The reactions proceed instantaneously at room temperature, affording alcohols in ≥90% ee. Importantly, the ArTi(O-i-Pr)3 reagent differentiates the ligand effectiveness in an order of H8-BINOL > BINOL > TADDOL > diol 3 > disulfonamide 2.
- Wu, Kuo-Hui,Zhou, Shuangliu,Chen, Chien-An,Yang, Mao-Chi,Chiang, Ruei-Tang,Chen, Chi-Ren,Gau, Han-Mou
-
-
Read Online
- New and improved ligands for highly enantioselective catalytic diphenylzinc additions to aryl aldehydes
-
By introducing electron-withdrawing fluorine atoms to a chiral 1,1'- binaphthyl ligand (R)-1, a new catalyst (S)-5d has been obtained which shows improved catalytic properties for the asymmetric diphenylzinc addition to aldehydes. This new ligand allows the synthesis of chiral diarylcarbinols with high enantioselectivity in shorter reaction time under simple reaction conditions.
- Huang, Wei-Sheng,Pu, Lin
-
-
Read Online
- Enantioselective addition of organozinc reagents to aldehydes catalyzed by 3,3′-bis(diphenylphosphinoyl)-BINOL
-
The enantioselective addition of organozinc reagents to aromatic and aliphatic aldehydes 1 gives secondary alcohols 2 with excellent enantioselectivities in high yields through the catalytic use of (R)-3,3′-bis(diphenylphosphinoyl)-BINOL (3) or (R)-3,3′- bis(diphenylthiophosphinoyl)-BINOL (4) without Ti(IV) complexes. The coordination of the O or S atom of a (thio)phosphinoyl group bearing a BINOL backbone to organozinc reagents can efficiently increase the nucleophilicity of the organozinc reagents.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
-
-
Read Online
- A highly enantioselective and catalytic aryl transfer reaction using mixed triarylbismuthane and dialkylzinc reagents
-
Highly enantioselective and catalytic aryl transfer reactions to aromatic aldehydes by using mixed triarylbismuthane and dimethylzinc reagents were studied. In the presence of a chiral β-amino alcohol catalyst, chiral diarylmethanols with up to 97 % ee were obtained. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Sato, Itaru,Toyota, Yousuke,Asakura, Noriaki
-
-
Read Online
- Zn(salen)-catalyzed enantioselective phenyl transfer to aldehydes and ketones with organozinc reagent
-
Abstract A chiral zinc complex of salen was found to be an efficient catalyst for the phenyl transfer of organozinc reagent to aromatic aldehydes and ketones. High enantioselectivities were obtained in reactions of both aromatic aldehydes and ketones (up to 97% and 92% ee, respectively).
- Shimizu, Keisuke,Uetsu, Hidenori,Gotanda, Takashi,Ito, Katsuji
-
-
Read Online
- Acceleration of arylzinc formation and its enantioselective addition to aldehydes by microwave irradiation and aziridine-2-methanol catalysts
-
(Chemical Equation Presented) The formation and 2-amino alcohol catalyzed addition of arylzinc reagents from and with boronic acids, respectively, is drastically accelerated to a few minutes under microwave irradiation without loss of enantioselectivity (up to 98% ee). Of the amino acid derived catalysts tested, the conformationally restricted bulky substituted aziridine-2-methanols derived from serine show the best overall performance in the formation of diarylmethanols.
- Braga, Antonio L.,Paixao, Marcio W.,Westermann, Bernhard,Schneider, Paulo H.,Wessjohann, Ludger A.
-
-
Read Online
- Synthesis of aminomethyl quinazoline based ruthenium (II) complex and its application in asymmetric transfer hydrogenation under mild conditions
-
The new chiral aminomethyl quinazoline (amq) type ligand derived from L-phenylalanine was synthesized and coordinated with [RuCl2(PPh3)dppb] to obtain ruthenium(II) complex. This catalyst displayed considerable reactivity (up to 97% ee and 99% conversion) in the asymmetric transfer hydrogenation of ketones using 2-propanol as a hydrogen source in the presence of NaOiPr.
- Agac, Ahmet,Karakaya, Idris,Sahin, Irfan,Emir, Sedat,Karabuga, Semistan,Ulukanli, Sabri
-
-
Read Online
- Catalytic enantioselective arylation of aldehydes: Boronic acids as a suitable source of transferable aryl groups
-
The catalytic enantioselective arylation of several aldehydes using boronic acids as the source of transferable aryl groups is described; the reaction is found to proceed in excellent yields and high enantioselectivities (up to 97% ee) in the presence of a chiral amino alcohol. The Royal Society of Chemistry 2005.
- Braga, Antonio L.,Luedtke, Diogo S.,Vargas, Fabricio,Paixao, Marcio W.
-
-
Read Online
- Hydroclassified Combinatorial Saturation Mutagenesis: Reshaping Substrate Binding Pockets of KpADH for Enantioselective Reduction of Bulky-Bulky Ketones
-
A hydroclassified combinatorial saturation mutagenesis (HCSM) strategy was proposed for reshaping the substrate binding pocket by dividing 20 amino acids into four groups based on their hydrophobicity and size. These smart HCSM libraries could significantly reduce screening effort especially for the simultaneous mutagenesis of three or more residues and lacking high throughput screening methods. Employing HCSM strategy, the stereoselectivity of KpADH, an alcohol dehydrogenase from Kluyveromyces polysporus, was efficiently improved to 99.4% ee. (4-Chlorophenyl)(pyridin-2-yl)methanone (CPMK), generally regarded as a "hard-to-reduce" ketone, was used as a model substrate, and its corresponding chiral alcohol products could be utilized as antihistamine precursors. The best variant 50C10 displayed higher binding affinity and catalytic efficiency toward CPMK with KM/kcat of 59.3 s-1·mM-1, 3.51-fold that of KpADH. Based on MD simulations, increased difference between two binding pockets, enhanced hydrophobicity, and π-π and halogen-alkyl interactions were proposed to favor the enantioselective recognition and substrate binding in 50C10. Substrate spectrum analysis revealed that 50C10 exhibited improved enantioselectivity toward diaryl ketones especially with halo- or other electron-withdrawing groups. As much as 500 mM CPMK could be asymmetrically reduced into chiral diaryl alcohols with ee of 99.4% and a space-time yield of 194 g·L-1·d-1 without addition of external NADP+. This study provides an effective mutagenesis strategy for the protein engineering of substrate specificity and enantioselectivity.
- Xu, Guo-Chao,Wang, Yue,Tang, Ming-Hui,Zhou, Jie-Yu,Zhao, Jing,Han, Rui-Zhi,Ni, Ye
-
-
Read Online
- 3,3′-diphosphoryl-1,1′-bi-2-naphthol-Zn(II) complexes as conjugate acid-base catalysts for enantioselective dialkylzinc addition to aldehydes
-
A highly enantioselective dialkylzine (R22Zn) addition to a series of aromatic, aliphatic, and heteroaromatic aldehydes (5) was developed based on conjugate Lewis acid-Lewis base catalysis. Bifunctional BINOL ligands bearing phosphine oxides [P(=O)R2] (7), phosphonates [P(=O)(OR)2] (8 and 9), or phosphoramides [P(=O)(NR2) 2] (10) at the 3,3′-positions were prepared by using a phospho-Fries rearrangement as a key step. The coordination of a NaphO-Zn(II)-R2 center as a Lewis acid to a carbonyl group in a substrate and the activation of R22Zn(II) with a phosphoryl group (P=O) as a Lewis base in the 3,3′-diphosphoryl-BINOL- Zn(II) catalyst could promote carbon-carbon bond formation with high enantioselectivities (up to >99% ee). Mechanistic studies were performed by X-ray analyses of a free ligand (7) and a tetranuclear Zn(II) cluster (21), a 31P NMR experiment on Zn(II) complexes, an absence of nonlinear effect between the ligand (7) and Et-adduct of benzaldehyde, and stoichiometric reactions with some chiral or achiral Zn(II) complexes to propose a transition-state assembly including monomeric active intermediates.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
-
-
Read Online
- Remarkably efficient enantioselective titanium(IV)-(R)-H 8-BINOLate catalyst for arylations to aldehydes by triaryl(tetrahydrofuran)aluminum reagents
-
Novel asymmetric triarylaluminum AlAr3(THF) additions to aldehydes catalyzed by 10 mol % of the titanium(IV) complex of (R)-H8-BINOL ligand are reported. The catalytic system is extremely efficient with reactions completing within 10 min. The system applies to the most diversified aldehydes to date, and more than 20 aldehydes were examined to afford diarylmethanols having an electron-donating or an electron-withdrawing group at the 2-, 3-, or 4-position on the aryl moiety, linear or branched 1-aryl aliphatic alcohols, aryl furyl methanols, 1-aryl allylic alcohols, and, especially, 1-aryl propargylic alcohols in excellent enantioselectivities of ≥90% ee, except for the case of 1-naphthyl addition to benzaldehyde. Noteworthily, diarylmethanols in both R- and S-configurations can be obtained. Copyright
- Wu, Kuo-Hui,Gau, Han-Mou
-
-
Read Online
- A novel ferrocenyl diselenide for the catalytic asymmetric aryl transfer to aldehydes
-
An oxazolinyl ferrocenyl diselenide was synthesised by directed ortho-metalation and used as catalyst precursor in the asymmetric addition of diethyl- and diphenylzinc to various aldehydes, yielding synthetically useful secondary alcohols, of which some are difficult to access using other catalytic methodologies. Enantioselectivities of up to 44% for the former and up to 85% for the latter transformations were obtained.
- Bolm,Kesselgruber,Grenz,Hermanns,Hildebrand
-
-
Read Online
- The Mg-oppenauer oxidation as a mild method for the synthesis of aryl and metallocenyl ketones
-
Magnesium alkoxides undergo a hydride-transfer oxidation with benzaldehyde as the oxidant. This magnesium variant of the Oppenauer oxidation was used for the synthesis of polyfunctional biaryl ketones. LiCl was found to promote this reaction by enhancing the solubility of magnesium alkoxides. This mild oxidation method was especially useful for preparing ketones bearing a metallocenyl unit as well as various new ferrocenyl ketones and tricarbonylchromium complexes. This last class of ketones was reduced with the CBS catalyst (CBS = Corey-Bakshi-Shibata, diphenyl oxazaborolidine) to chiral benzhydrol complexes with high enantioselectivity enabling an asymmetric synthesis of electronrich or -poor benzhydryl alcohols (up to 94% ee).
- Kloetzing, Ralf J.,Krasovskiy, Arkady,Knochel, Paul
-
-
Read Online
- Synthesis of novel planar chiral Ag and Rh N-heterocyclic carbene complexes derived from [2.2]paracyclophane and their application in ultrasound assisted asymmetric addition reactions of organoboronic acids to aldehydes
-
Three novel planar chiral N-heterocyclic carbene silver and rhodium complexes based on [2.2]paracyclophane have been prepared. These could be used as catalysts/precatalysts for the asymmetric 1,2-addition of organoboronic acids to aldehydes. We optimized the reaction conditions and have applied ultrasonic irradiation in the asymmetric arylation for the first time. Under ultrasound irradiation, the combination of planar chiral NHC-Ag complex 5 and RhCl 3 can achieve higher catalytic activities in the asymmetric addition of organoboronic acids to aldehydes.
- Duan, Wenzeng,Ma, Yudao,He, Fuyan,Zhao, Lei,Chen, Jianqiang,Song, Chun
-
-
Read Online
- Synthesis of new alkoxy/sulfonate-substituted carbene precursors derived from [2.2]paracyclophane and their application in the asymmetric arylation of aldehydes
-
A series of novel planar chiral alkoxy/sulfonate-substituted carbene precursors have been designed and synthesized. They were used as N-heterocyclic carbene ligands in the Rh-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- Duan, Wenzeng,Ma, Yudao,Qu, Bo,Zhao, Lei,Chen, Jianqiang,Song, Chun
-
-
Read Online
- Molecular switch manipulating Prelog priority of an alcohol dehydrogenase toward bulky-bulky ketones
-
Structure-guided rational design revealed the molecular switch manipulating the Prelog and anti-Prelog priorities of an NADPH-dependent alcohol dehydrogenase toward prochiral ketones with bulky and similar substituents. Synergistic effects of unconserved residues at 214 and 237 in small and large substrate binding pockets were proven to be vital in governing the stereoselectivity. The ee values of E214Y/S237A and E214C/S237 G toward (4-chlorophenyl)-(pyridin-2-yl)-methanone were 99.3% (R) and 78.8% (S) respectively. Substrate specificity analysis revealed that similar patterns were also found with (4’-chlorophenyl)-phenylmethanone, (4’-bromophenyl)-phenylmethanone and (4’-nitrophenyl)-phenylmethanone. This study provides valuable evidence for understanding the molecular mechanism on enantioselective recognition of prochiral ketones by alcohol dehydrogenase.
- Xu, Guochao,Dai, Wei,Wang, Yue,Zhang, Lu,Sun, Zewen,Zhou, Jieyu,Ni, Ye
-
-
Read Online
- Enantioselective rhodium-catalyzed addition of arylboronic acids to aldehydes using chiral spiro monophosphite ligands
-
Highly efficient rhodium-catalyzed asymmetric addition of arylboronic acids to aldehydes has been realized by using chiral spiro monophosphite ligands, affording diarylmethanols in excellent yields and good enantiomeric excesses.
- Duan, Hai-Feng,Xie, Jian-Hua,Shi, Wen-Jian,Zhang, Qi,Zhou, Qi-Lin
-
-
Read Online
- Modular chiral thiazolidine catalysts in asymmetric aryl transfer reactions
-
Modular chiral thiazolidine derivatives were synthesized in a single step from inexpensive and commercially available starting materials. These ligands catalyzed enantioselective arylation of different aldehydes using aryl boronic acids as a source of transferable aryl groups. The products were obtained in excellent yields and good enantioselectivities.
- Braga, Antonio Luiz,Milani, Priscila,Vargas, Fabricio,Paixao, Marcio W.,Sehnem, Jasquer A.
-
-
Read Online
- Catalytic enantioselective aryl transfer: Asymmetric addition of boronic acids to aldehydes using pyrrolidinylmethanols as ligands
-
Pyrrolidinylmethanols, easily accessible from readily available (S)-proline, were applied in zinc-catalyzed addition of arylboronic acids to aromatic aldehydes; the reaction was found to proceed in excellent yields and high enantioselectivities (up to 98% ee).
- Braga, Antonio L.,Lüdtke, Diogo S.,Schneider, Paulo H.,Vargas, Fabricio,Schneider, Alex,Wessjohann, Ludger A.,Paix?o, Márcio W.
-
-
Read Online
- Asymmetric 1,4-addition of organoboronic acids to α,β-unsaturated ketones and 1,2-addition to aldehydes catalyzed by a palladium complex with a ferrocene-based phosphine ligand
-
A combination of palladium with ferrocene-based phosphine ligand with a carbon-bromine bond was found to be a good catalyst for the 1,4-addition of arylboronic acids to α,β-unsaturated ketones and the 1,2-addition to aldehydes. Using Pd(dba)2 and (S,Rp)-[1-(2-bromoferrocenyl)ethyl]diphenylphosphine (S,Rp)-1, 3-phenylcyclohexanone was obtained from the reaction of 2-cyclohexen-1-one with phenylboronic acid in the presence of K2CO3 in toluene at room temperature after 3 h in 92% yield with 76% ee. In the 1,2-addition of 4-methylphenylboronic acid to benzaldehyde, 96% of (4-methylphenyl)phenylmethanol was afforded after 24 h, while the enantiomeric excess was only 6%.
- Suzuma, Yoshinori,Hayashi, Shoko,Yamamoto, Tetsuya,Oe, Yohei,Ohta, Tetsuo,Ito, Yoshihiko
-
-
Read Online
- Highly enantioselective addition of diphenylzinc to aliphatic and aromatic aldehydes catalyzed by a readily available H8-binol derivative
-
(Chemical Equation Presented) All sorts of aldehydes 2 (R = aryl, vinyl, branched, and linear alkyl) undergo the highly enantioselective addition of diphenylzinc (1) in the presence of catalytic (S)-4 to give α-substituted benzyl alcohols 3 in high yields. In contrast to previous catalysts, no additive is required, the reaction is carried out at room temperature, and the reaction is equally effective with linear aldehydes.
- Qin, Ying-Chuan,Pu, Lin
-
-
Read Online
- Highly enantioselective addition of in situ prepared arylzinc to aldehydes catalyzed by a series of atropisomeric binaphthyl-derived amino alcohols
-
The direct addition of in situ prepared arylzinc to aldehydes with chiral binaphthyl-derived amino alcohols as catalysts can afford optically active diarylmethanols in high yields and with excellent enantioselectivities (up to 99% ee, ee = enantiomeric excess). By using a single catalyst, both enantiomers of many pharmaceutically interesting diarylmethanols can be obtained by the proper combination of various arylzinc reagents with different aldehydes; this catalytic system also works well for the phenylation of aliphatic aldehydes to give up to 96 % ee.
- Lu, Gui,Kwong, Fuk Yee,Ruan, Ji-Wu,Li, Yue-Ming,Chan, Albert S. C.
-
-
Read Online
- Rhodium/phosphoramidite-catalyzed asymmetric arylation of aldehydes with arylboronic acids
-
Phosphoramidites are effective chiral ligands in the rhodium catalyzed addition of arylboronic acids to aldehydes providing up to 75% enantioselectivity and up to 96% isolated yield. The Royal Society of Chemistry 2006.
- Jagt, Richard B.C.,Toullec, Patrick Y.,De Vries, Johannes G.,Feringa, Ben L.,Minnaard, Adriaan J.
-
-
Read Online
- Triarylborane ammonia complexes as ideal precursors for arylzinc reagents in asymmetric catalysis
-
(Chemical Equation Presented) The value of arylboranes as precursors for arylzinc reagents in asymmetric catalysis is demonstrated. Kinetic studies on the transmetalation reaction with zinc reagents rationalize the observed differences of three classes of arylboranes in catalytic applications. By using the stable and easily accessible triarylborane ammonia complexes, an array of chiral diarylmethanols in high yield and enantioselectivity was synthesized.
- Dahmen, Stefan,Lormann, Matthias
-
-
Read Online
- Asymmetric Catalysis Using Aromatic Aldehydes as Chiral α-Alkoxyalkyl Anions
-
We have developed a new umpolung strategy for catalytically forming a chiral α-alkoxyalkyl anion from an aromatic aldehyde for use in asymmetric synthesis. The reaction between aromatic aldehydes and aryl or allyl electrophiles with a silylboronate utilizing a chiral copper-N-heterocyclic carbene catalyst and a palladium-bisphosphine catalyst in a synergistic manner occurred with high enantioselectivities to deliver the three-component coupling products, chiral silyl-protected secondary alcohol derivatives. Our method features the catalytic generation of enantioenriched chiral α-alkoxyalkylcopper(I) intermediates from aldehydes and their subsequent palladium-catalyzed stereospecific cross-coupling.
- Yabushita, Kenya,Yuasa, Akihiro,Nagao, Kazunori,Ohmiya, Hirohisa
-
-
Read Online
- Organosilanols as catalysts in asymmetric aryl transfer reactions
-
(Chemical Equation Presented) Various ferrocene-based organosilanols have been synthesized in four steps starting from achiral ferrocene carboxylic acid. Applying these novel planar-chiral ferrocenes as catalysts in asymmetric phenyl transfer reactions to substituted benzaldehydes afforded products with high enantiomeric excesses. The best result (91% ee) was achieved in the addition to p-chlorobenzaldehyde with organosilanol 2b, which has a tert-butyl substituent on the oxazoline ring and an isopropyl group on the silanol fragment.
- Oezcubukcu, Salih,Schmidt, Frank,Bolm, Carsten
-
-
Read Online
- Highly enantioselective phenyl transfer to aryl aldehydes catalyzed by easily accessible chiral tertiary aminonaphthol
-
(Chemical Equation Presented) A new chiral tertiary aminonaphthol ligand 3b served as a highly efficient ligand for the asymmetric catalytic phenyl transfer to aromatic aldehydes and a variety of chiral diarylmethanols was prepared in high ee values (ee up to 99%) and chemical yields. The straightforward syntheses of both 3b and its enantiomer provide an excellent opportunity for large-scale applications.
- Ji, Jian-Xin,Wu, Jing,Au-Yeung, Terry T.-L.,Yip, Chiu-Wing,Haynes, Richard K.,Chan, Albert S. C.
-
-
Read Online
- Chiral 1,1′-binaphthylazepine-derived amino alcohol catalyzed asymmetric aryl transfer reactions with boroxine as aryl source
-
Using chiral 1,1′-binaphthylazepine-derived amino alcohol as catalyst, the direct addition of in situ prepared arylzinc (with triphenylboroxine as aryl source) to various aryl aldehydes can afford optically active diarylmethanols in high yields and enantioselectivities (up to 96%).
- Liu, Can,Guo, Zong-Liang,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
-
-
Read Online
- From aryl bromides to enantioenriched benzylic alcohols in a single flask: Catalytic asymmetric arylation of aldehydes
-
(Chemical Equation Presented) Stop that achiral catalyst! Chiral Lewis acid catalyzed aryl additions to aldehydes that originate from aryl halides generate products with very low ee values (see scheme, left), because the achiral metal halide by-products are much more efficient catalysts than those derived from chiral amino alcohols. A LiCl-selective inhibitor is introduced that enables a highly enantioselective one-pot arylation of aldehydes that begins with aryl bromides (right).
- Kim, Jeung Gon,Walsh, Patrick J.
-
-
Read Online
- Application of β-hydroxysulfoximines in catalytic asymmetric phenyl transfer reactions for the synthesis of diarylmethanols
-
(Chemical Equation Presented) Enantiomerically enriched diarylmethanols have been prepared by catalyzed asymmetric phenyl transfer reactions onto aromatic aldehydes with use of readily available β-hydroxysulfoximines as catalysts. As the aryl source, combinations of diethylzinc with either diphenylzinc or triphenylborane have been applied affording arylphenylmethanols with up to 93% ee in good yields. Various functionalized aldehydes and heterocyclic substrates are tolerated, yielding synthetically relevant products.
- Sedelmeier, Joerg,Bolm, Carsten
-
-
Read Online
- Enantioselective phenyl transfer to aldehydes using 1,1′-bi-2- naphthol-3,3′-dicarboxamide as chiral auxiliary
-
N,N,N′,N′-Tetra-n-butyl-BINOL-3,3′-dicarboxamide 5d was found to promote phenyl transfer from ethylphenylzinc to both aromatic and aliphatic aldehydes with high enantioselectivity up to 96% ee in tert-butyl methyl ether.
- Ito, Katsuji,Tomita, Yuki,Katsuki, Tsutomu
-
-
Read Online
- Fine tuning the enantioselectivity and substrate specificity of alcohol dehydrogenase from Kluyveromyces polysporus by single residue at 237
-
Here, S237 was identified to be important in fine tuning the substrate specificity and enantioselectivity of alcohol dehydrogenase from Kluyveromyces polysporus (KpADH). In the reduction of a diaryl ketone, (4-chlorophenyl)-(pyridin-2-yl)-methanone (1a), the highest and lowest enantioselectivity of 96.1% and 27.0% e.e. (R) were obtained with S237A and S237C. Kinetic parameters analysis revealed that S237G, S237A, S237H and S237D displayed improved kcat/Km toward 1a. Various prochiral ketones, including acetophenone, 4-chloroacetophenone and ethyl 2-oxo-4-phenylbutyrate could be asymmetrically reduced by S237C, S237G and S237E with > 99% e.e. This study provides guidance for the application of KpADH in the preparation of chiral secondary alcohols.
- Wang, Yue,Dai, Wei,Liu, Yongmei,Zhang, Zhongwei,Zhou, Jieyu,Xu, Guochao,Ni, Ye
-
-
Read Online
- Candida zeylanoides as whole-cell biocatalyst to perform asymmetric bioreduction of benzophenone derivatives
-
Candida zeylanoides P1 was investigated as whole cell biocatalyst for the bioreduction of biaryl prochiral ketones into chiral carbinols, which can be used as pharmaceutical intermediate. Bioreduction of different biaryl ketones was carried out to their corresponding chiral biaryl carbinols such as (S)-(4-chlorophenyl) (phenyl) methanol (2a), which can be used in the synthesis of L-cloperastine drug, with antitussive, antiepidemic activity and bronchial musculature relaxant characteristics, in gram scale, enantiopure form (>99%) and excellent yields. The selectivity of C. zeylanoides P1 in enantioselective reduction of biaryl ketones was not affected by the steric and electronic effects of substrates. The current method demonstrates an encouraging green chemistry approach for the production of biaryl secondary chiral alcohols of pharmaceutical importance in mild, inexpensive and environmentally friendly process. The present study has many benefits since this yeast biocatalyst were successfully applied bioreduction of structurally bulky prochiral substrates, which cannot be reducted by chemical catalysis.
- ?ahin, Engin
-
-
Read Online
- Catalyzed asymmetric aryl transfer reactions to aldehydes with boronic acids as aryl source
-
Chiral diaryl methanols are important intermediates for the synthesis of biologically active compounds. Here, we describe a flexible method for their catalyzed asymmetric synthesis from readily available starting materials. Noteworthy is the fact that wit
- Bolm, Carsten,Rudolph, Jens
-
-
Read Online
- Engineering an alcohol dehydrogenase with enhanced activity and stereoselectivity toward diaryl ketones: Reduction of steric hindrance and change of the stereocontrol element
-
Steric hindrance in the binding pocket of an alcohol dehydrogenase (ADH) has a great impact on its activity and stereoselectivity simultaneously. Due to the subtle structural difference between two bulky phenyl substituents, the asymmetric synthesis of diaryl alcohols by bioreduction of diaryl ketones is often hindered by the low activity and stereoselectivity of ADHs. To engineer an ADH with practical properties and to investigate the molecular mechanism behind the asymmetric biocatalysis of diaryl ketones, we engineered an ADH from Lactobacillus kefiri (LkADH) to asymmetrically catalyse the reduction of 4-chlorodiphenylketones (CPPK), which are not catalysed by the wild type (WT) enzyme. Mutants seq1-seq5 with gradually increased activity and stereoselectivity were obtained through iterative "shrinking mutagenesis." The final mutant seq5 (Y190P/I144V/L199V/E145C/M206F) demonstrated the highest activity and excellent stereoselectivity of >99% ee. Molecular simulation analyses revealed that mutations may enhance the activity by eliminating steric hindrance, inducing a more open binding loop and constructing more noncovalent interactions. The pro-R pose of CPPK with a halogen bond formed a pre-reaction conformation more easily than the pro-S pose, resulting in the high ee of (R)-CPPO in seq5. Moreover, different halogen bonds formed due to the different positions of chlorine substituents, resulting in opposite substrate binding orientation and stereoselectivity. Therefore, the stereoselectivity of seq5 was inverted toward ortho- rather than para-chlorine substituted ketones. These results indicate that the stereocontrol element of LkADH was changed to recognise diaryl ketones after steric hindrance was eliminated. This study provides novel insights into the role of steric hindrance and noncovalent bonds in the determination of the activity and stereoselectivity of enzymes, and presents an approach producing key intermediates of chiral drugs with practical potential.
- Chen, Rong,Huang, Jiankun,Meng, Xiangguo,Shao, Lei,Wu, Kai,Yang, Zhijun
-
-
Read Online
- STEREOSELECTIVE REDUCTION OF SUBSTITUTED BENZOPHENONES BY MICROORGANISMS I.
-
Debaryomyces marama enentioselectively reduces p-Cl-benzophenone to the S-alcohol with high enantiomeric excess.
- Spassov, G.,Pramatarova, V.,Vlahov, R.,Snatzke, G.
-
-
Read Online
- Bio-inspired asymmetric aldehyde arylations catalyzed by rhodium-cyclodextrin self-inclusion complexes
-
Transition-metal catalysts are powerful tools for carbon-carbon bond-forming reactions that are difficult to achieve using native enzymes. Enzymes that exhibit inherent selectivities and reactivities through host-guest interactions have inspired widesprea
- Asahi, Kaoru,Fujiwara, Shin-Ichi,Iwasaki, Takanori,Kambe, Nobuaki,Takahashi, Ryota,Tsuda, Susumu,Ueda, Ryoji,Yamauchi, Hiroki
-
supporting information
p. 801 - 807
(2022/02/03)
-
- Amino Acid-Functionalized Metal-Organic Frameworks for Asymmetric Base–Metal Catalysis
-
We report a strategy to develop heterogeneous single-site enantioselective catalysts based on naturally occurring amino acids and earth-abundant metals for eco-friendly asymmetric catalysis. The grafting of amino acids within the pores of a metal-organic framework (MOF), followed by post-synthetic metalation with iron precursor, affords highly active and enantioselective (>99 % ee for 10 examples) catalysts for hydrosilylation and hydroboration of carbonyl compounds. Impressively, the MOF-Fe catalyst displayed high turnover numbers of up to 10 000 and was recycled and reused more than 15 times without diminishing the enantioselectivity. MOF-Fe displayed much higher activity and enantioselectivity than its homogeneous control catalyst, likely due to the formation of robust single-site catalyst in the MOF through site-isolation.
- Newar, Rajashree,Akhtar, Naved,Antil, Neha,Kumar, Ajay,Shukla, Sakshi,Begum, Wahida,Manna, Kuntal
-
p. 10964 - 10970
(2021/03/29)
-
- Rhizopus arrhizus mediated SAR studies in chemoselective biotransformation of haloketones at ambient temperature
-
We have demonstrated a green chemistry approach using the fungus Rhizopus arrhizus for the reductive dehalogenation and synthesis of chiral secondary carbinols and halohydrins of pharmaceutical importance in mild, inexpensive, and environmental friendly process at ambient temperature. In the present study, we have succeeded in unravelling the relationship between the position of the substituent group in the structure of substrate and bioreduction activity of the fungus Rhizopus arrhizus. The asymmetric reduction of the carbonyl group to corresponding chiral halohydrin takes place with good yield and excellent enantiomeric excess (≥92%) when the substituent halogen is on the aromatic nucleus. However, novel results concerning reductive dehalogenation are obtained when halogen is incorporated in the alkyl side chain. Thus, the fungus Rhizopus arrhizus has great potential to bring chemoenzymatic biotransformation of halo ketones. Various influential processing parameters such as microbe selection, temperature, pH, etc. were also investigated to optimize the growth of biocatalyst.
- Salokhe, Prabha R.,Salunkhe, Rajeshri S.
-
-
- Electronic Effect-Guided Rational Design of Candida antarctica Lipase B for Kinetic Resolution Towards Diarylmethanols
-
Herein, we developed an electronic effect-guided rational design strategy to enhance the enantioselectivity of Candida antarctica lipase B (CALB) mutants towards bulky pyridyl(phenyl)methanols. Compared to W104A mutant previously reported with reversed S-stereoselectivity toward sec-alcohols, three mutants (W104C, W104S and W104T) displayed significant improvement of S-enantioselectivity in the kinetic resolution (KR) of various phenyl pyridyl methyl acetates due to the increased electronic effects between pyridyl and polar residues. The electronic effects were also observed when mutating other residues surrounding the stereospecificity pocket of CALB, such as T42A, S47A, A281S or A281C, and can be used to manipulate the stereoselectivity. A series of bulky pyridyl(phenyl) methanols, including S-(4-chlorophenyl)(pyridin-2-yl) methanol (S-CPMA), the intermediate of bepotastine, were obtained in good yields and ee values. (Figure presented.).
- Li, Dan-Yang,Lou, Yu-Jiao,Xu, Jian,Chen, Xiao-Yang,Lin, Xian-Fu,Wu, Qi
-
p. 1867 - 1872
(2021/02/12)
-
- Binaphthyl-prolinol chiral ligands: Design and their application in enantioselective arylation of aromatic aldehydes
-
Binaphthyl-prolinol ligands were designed and applied in enantioselective arylation of aromatic aldehydes and sequential arylation-lactonization of methyl 2-formylbenzoate. Under optimized conditions, the reactions provided the desired diarylmethanols and 3-aryl phthalides in up to 96% yields with up to 99% ee and up to 89% yields with up to 99% ee, respectively. In particular, essentially optically pure 3-aryl phthalides (over 99% ee) were obtained in large quantities through recrystallization. This journal is
- Yao, Chao,Chen, Yaoqi,Sun, Ruize,Wang, Chao,Huang, Yue,Li, Lin,Li, Yue-Ming
-
supporting information
p. 3644 - 3655
(2021/05/04)
-
- Isosterically designed chiral catalysts: Rationale, optimization and their application in enantioselective nucleophilic addition to aldehydes
-
Proline-based N,N′-dioxide ligands were designed on the basis of isosteric approach, and were successfully applied in enantioselective nucleophilic addition to aldehydes. In the presence of 10 mol% of chiral ligand 1b, enantioselective addition of diethylzinc to aldehydes provided the corresponding secondary alcohols in up to 90% isolated yield and up to 99% ee. Similarly, using 3e as chiral ligand, enantioselective arylation and alkynylation of aldehydes also proceeded readily, leading to the desired chiral alcohols in up to 92% isolated yield at 99% ee and 80% isolated yields and up to 84% ee, respectively. The current work would shed light on expanding the structure diversity in the design of chiral ligands and chiral catalysts.
- Gao, En,Li, Qiao,Duan, Lili,Li, Lin,Li, Yue-Ming
-
supporting information
(2020/10/20)
-
- Substituent Position-Controlled Stereoselectivity in Enzymatic Reduction of Diaryl- and Aryl(heteroaryl)methanones
-
We report here the discovery of a novel ketoreductase (KRED), named KmCR2, with a broad substrate spectrum on bioreduction of sterically bulky diaryl- and aryl(heteroaryl)methanones. The position of the substituent on aromatic rings (meta versus para or ortho) was revealed to control the stereospecificity of KmCR2. The stereoselective preparation of both enantiomers of diaryl- or aryl(heteroaryl)methanols using strategically engineered substrates with a traceless directing group (bromo group) showcased the potential application of this substrate-controlled bioreduction reaction. The combined use of substrate engineering and protein engineering, was demonstrated to be a useful strategy in efficiently improving stereoselectivity or switching stereopreference of enzymatic processes. (Figure presented.).
- Li, Zhining,Wang, Zexu,Wang, Yuhan,Wu, Xiaofan,Lu, Hong,Huang, Zedu,Chen, Fener
-
supporting information
p. 1859 - 1865
(2019/03/07)
-
- Development of Chiral C2-Symmetric N-Heterocyclic Carbene Rh(I) Catalysts through Control of Their Steric Properties
-
Chiral square-planar Rh(I) complexes based on new C2-symmetric NHC ligands have been synthesized selectively in a few steps as single diastereoisomers. These chiral precatalysts were applied to the asymmetric transfer hydrogenation of 1-phenylp
- Abadie, Marc-Antoine,Macintyre, Kirsty,Boulho, Cédric,Hoggan, Peter,Capet, Frédéric,Agbossou-Niedercorn, Francine,Michon, Christophe
-
p. 536 - 543
(2019/01/14)
-
- Asymmetric Catalysis in Liquid Confinement: Probing the Performance of Novel Chiral Rhodium–Diene Complexes in Microemulsions and Conventional Solvents
-
The role of liquid confinement on the asymmetric Rh catalysis was studied using the 1,2-addition of phenylboroxine (2) to N-tosylimine 1 in the presence of [RhCl(C2H4)2]2 and chiral diene ligands as benchmark reaction. To get access to Rh complexes of different polarity, enantiomerically pure C2-symmetric p-substituted 3,6-diphenylbicyclo[3.3.0]octadienes 4 and diastereomerically enriched unsymmetric norbornadienes 5 and 6 carrying either the Evans or the SuperQuat auxiliary were synthesized. A microemulsion containing the equal amounts of H2O/KOH and toluene/reactants was formulated using the hydrophilic sugar surfactant n-octyl β-d-glucopyranoside (C8G1) to mediate the miscibility between the nonpolar reactants and KOH, needed to activate the Rh–diene complex. Prominent features of this organized reaction medium are its temperature insensitivity as well as the presence of water and toluene-rich compartments with a domain size of 55 ? confirmed by small-angle X-ray scattering (SAXS). Although bicyclooctadiene ligands 4 a,b,e performed equally well under homogeneous and microemulsion conditions, ligands 4 c,d gave a different chemoselectivity. For norbornadienes 5, 6, however, microemulsions markedly improved conversion and enantioselectivity as well as reaction rate, as was confirmed by kinetic studies using ligand 5 b.
- Deimling, Max,Kirchhof, Manuel,Schwager, Barbara,Qawasmi, Yaseen,Savin, Alex,Mühlh?user, Tina,Frey, Wolfgang,Claasen, Birgit,Baro, Angelika,Sottmann, Thomas,Laschat, Sabine
-
supporting information
p. 9464 - 9476
(2019/07/04)
-
- Silica-Supported Catalyst for Enantioselective Arylation of Aldehydes under Batch and Continuous-Flow Conditions
-
A silica-supported 3-aryl H8-BINOL-derived titanium catalyst exhibited high performance in the enantioselective arylation of aromatic aldehydes using Grignard and organolithium reagents not only under batch conditions but also under continuous-
- Watanabe, Satoshi,Nakaya, Naoyuki,Akai, Junichiro,Kanaori, Kenji,Harada, Toshiro
-
supporting information
p. 2737 - 2740
(2018/05/22)
-
- Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones
-
A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, (S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, (R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.
- Ling, Fei,Nian, Sanfei,Chen, Jiachen,Luo, Wenjun,Wang, Ze,Lv, Yaping,Zhong, Weihui
-
p. 10749 - 10761
(2018/09/06)
-
- Asymmetric Transfer Hydrogenation of (Hetero)arylketones with Tethered Rh(III)-N-(p-Tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine Complexes: Scope and Limitations
-
A series of new tethered Rh(III)/Cp? complexes containing the N-(p-tolylsulfonyl)-1,2-diphenylethylene-1,2-diamine ligand have been prepared, characterized, and evaluated in the asymmetric transfer hydrogenation (ATH) of a wide range of (hetero)aryl ketones. The reaction was performed under mild conditions with the formic acid/triethylamine (5:2) system as the hydrogen source and provided enantiomerically enriched alcohols with good yields and high to excellent enantioselectivities. Although the nature of the substituents on the phenyl tethering ring did not alter the stereochemical outcome of the reaction, complexes bearing electron-donating groups exhibited a higher catalytic activity than those having electron-withdrawing groups. A scale-up of the ATH of 4-chromanone to the gram scale quantitatively delivered the reduced product with excellent enantioselectivity, demonstrating the potential usefulness of these new complexes.
- Zheng, Long-Sheng,Llopis, Quentin,Echeverria, Pierre-Georges,Férard, Charlène,Guillamot, Gérard,Phansavath, Phannarath,Ratovelomanana-Vidal, Virginie
-
p. 5607 - 5615
(2017/06/07)
-
- Chiral thiophosphoramide catalyzed asymmetric aryl transfer reactions for the synthesis of functional diarylmethanols
-
In this investigation, chiral thiophosphoramide 3d was easily prepared from chiral (1R,2R)-1,2-diphenylethylenediamine and then applied as an efficient chiral ligand in the catalytic asymmetric arylation reactions of various aromatic aldehydes. The corresponding diarylmethanol products were produced with good to excellent yields (up to 98%) and enantioselectivities (up to 94%). The recovery of chiral ligand 3d could be as high as 96%.
- Wang, Yabai,Zong, Hua,Huang, Huayin,Song, Ling
-
-
- Highly enantioselective asymmetric reactions involving zinc ions promoted by chiral aziridine alcohols
-
Enantiomerically pure, chiral secondary and tertiary aziridine alcohols (including the aziridine analogue of ProPhenol—AziPhenol) have proven to be highly effective catalysts for enantioselective asymmetric reactions in the presence of zinc ions, including arylation of aromatic aldehydes, epoxidation of chalcone and addition of diethylzinc to aldehydes, leading to the desired chiral products in high chemical yields (up to 90%) and with ee's up to 90%. A higher catalytic activity of Prophenol-type bis(aziridine alcohol) in the aforementioned asymmetric transformations has been demonstrated.
- Jarzyński, Szymon,Utecht, Greta,Le?niak, Stanis?aw,Rachwalski, Micha?
-
p. 1774 - 1779
(2017/11/16)
-
- HPLC enantioseparation on a homochiral MOF-silica composite as a novel chiral stationary phase
-
The last frontier in the development of chiral stationary phases for chromatographic enantioseparation involves homochiral metal-organic frameworks (MOFs). Using enantiopure (R)-2,2′-dihydroxy-1,1′-binaphthalene-6,6′-dicarboxylic acid as a starting material, we prepared three homochiral MOFs that were further used as chiral stationary phases for high-performance liquid chromatography to separate the enantiomers of various kinds of racemic sulfoxides, sec-alcohols, β-lactams, benzoins, flavanones and epoxides. The experimental results showed excellent performances for enantioseparation, and highlighted that enantioseparation on homochiral MOF columns is practical.
- Tanaka, Koichi,Muraoka, Toshihide,Otubo, Yasuhiro,Takahashi, Hiroki,Ohnishi, Atsushi
-
p. 21293 - 21301
(2016/03/08)
-
- Synthesis of new benzimidazolium salts and their application in the asymmetric arylation of aldehydes
-
A series of novel chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in asymmetric Rh-catalyzed arylation of aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- He, Wei-Ping,Zhou, Bi-Hui,Zhou, Ya-Li,Li, Xiang-Rong,Fan, Li-Mei,Shou, Hao-Wen,Li, Jie
-
supporting information
p. 3152 - 3155
(2016/07/06)
-
- Enantioselective addition of organozinc reagents to carbonyl compounds catalyzed by a camphor derived chiral γ-amino thiol ligand
-
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
-
p. 2656 - 2665
(2016/05/10)
-
- Efficient Access to Chiral Benzhydrols via Asymmetric Transfer Hydrogenation of Unsymmetrical Benzophenones with Bifunctional Oxo-Tethered Ruthenium Catalysts
-
A concise asymmetric transfer hydrogenation of diaryl ketones, promoted by bifunctional Ru complexes with an etherial linkage between 1,2-diphenylethylenediamine (DPEN) and η6-arene ligands, was successfully developed. Because of the effective discrimination of substituents at the ortho position on the aryl group, unsymmetrical benzophenones were smoothly reduced in a 5:2 mixture of formic acid and triethylamine with an unprecedented level of excellent enantioselectivity. For the non-ortho-substituted benzophenones, the oxo-tethered catalyst electronically discerned biased substrates, resulting in attractive performance yielding chiral diarylmethanols with >99% ee.
- Touge, Taichiro,Nara, Hideki,Fujiwhara, Mitsuhiko,Kayaki, Yoshihito,Ikariya, Takao
-
supporting information
p. 10084 - 10087
(2016/09/03)
-
- Highly enantioselective addition of arylzinc reagents to aldehydes promoted by chiral aziridine alcohols
-
Enantiomerically pure, chiral secondary and tertiary aziridine alcohols have proven to be highly efficient catalysts for enantioselective asymmetric additions of arylzinc species to aldehydes leading to products in high chemical yields (up to 90%) and with ee's up to 90%. The influence of the stereogenic centers located at the aziridine subunit on the stereochemical course of the reaction is discussed.
- Wujkowska, Zuzanna,Jarzyński, Szymon,Pieczonka, Adam M.,Le?niak, Stanis?aw,Rachwalski, Micha?
-
p. 1238 - 1244
(2016/11/23)
-
- Novel Intermediate of L-Cloperastine and Preparation Method Thereof
-
The present invention refers to pharmaceutically useful as well as novel intermediates of [...][...] -L (cloperastine) manufacturing method relates to and, more specifically a device with structure of formula 1 L- [...] intermediates manufacturing method of using enzymes relates to. Formula 1 , The, R the C1-C3 copyright 2000. (by machine translation)
- -
-
Paragraph 0032-0034
(2016/12/01)
-
- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
-
Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
-
p. 9368 - 9373
(2015/02/19)
-
- Aryl bromides as inexpensive starting materials in the catalytic enantioselective arylation of aryl aldehydes: The additive TMEDA enhances the enantioselectivity
-
We used aryl bromides as inexpensive starting materials to enantioselectively arylate aldehydes in one pot. Aryl bromides readily transfer aryls to aryllithiums with n-butyllithium, successively to triarylaluminums with aluminum chloride, and then to aryltitaniums with titanium isopropoxide. Finally aryltitaniums arylate aldehydes catalyzed by (S)-H8-BINOL-Ti(Oi-Pr)2 in excellent yields and enantioselectivities. The additive TMEDA evidently suppresses the racemic background reaction promoted by LiCl generated from salt metathesis. This procedure represents a cost-effective and operationally convenient method for enantioenriched diarylmethanols.
- Yang, Yong-Xin,Liu, Yue,Zhang, Lei,Jia, Yan-E,Wang, Pei,Zhuo, Fang-Fang,An, Xian-Tao,Da, Chao-Shan
-
p. 10696 - 10702
(2015/02/19)
-
- Enantioselective transfer reaction of phenyl to aldehydes using L-Proline-derived amino alcohols as chiral ligands
-
((S)-1-(1,3,5-trimethyl)benzylpyrrolidin-2-yl)diphenylmethanol (1d) was found to be an effective chiral ligand in the asymmetric transfer reaction of phenyl to aldehydes to give the corresponding adducts in excellent enantioselectivity (up to 98% ee) with very high yields (up to 99%).
- Liu, Yongmin,Bo, Rongcheng,Wu, Nan,Qiao, Yuehua,Li, Yong,Wu, Hui,Xu, Zhou
-
p. 356 - 360
(2014/05/20)
-
- Diastereomeric aziridine carbinol catalyzed enantioselective arylation reaction: Toward the asymmetric synthesis of both enantiomers of chiral 3-aryl phthalide
-
The diastereomeric aziridine carbinols are applied, respectively, as efficient chiral ligand in the catalysis of asymmetric arylation and sequential arylation-lactonization cascade. The two diastereomers, which are facilely synthesized from the same chiral source, function as pseudo enantiomers in arylation of aromatic aldehydes providing the different enantiomers of the diarylmethanols with almost the same excellent enantioselectivities. The arylation method is also carried out in tandem with lactonization process to afford a concise synthetic approach to both enantiomers of optically active 3-aryl phthalide.
- Song, Xixi,Hua, Yuan-Zhao,Shi, Jing-Guo,Sun, Ping-Ping,Wang, Min-Can,Chang, Junbiao
-
p. 6087 - 6093
(2014/07/21)
-
- Practical enantioselective arylation and heteroarylation of aldehydes with in situ prepared organotitanium reagents catalyzed by 3-aryl-H 8-BINOL-derived titanium complexes
-
A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl- and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP-H 8-BINOL (3 d; DPP=3,5-diphenylphenyl) and DTBP-H8-BINOL (3 e; DTBP=3,5-di-tert-butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2-thienylmethanols can be synthesized enantioselectively by using commercially available 2-thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol % catalyst loading, demonstrating its preparative utility. Titanium does it! Titanium complexes derived from 3-aryl-H8-BINOLs exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol %; see scheme). Copyright
- Uenishi, Ami,Nakagawa, Yuya,Osumi, Hironobu,Harada, Toshiro
-
supporting information
p. 4896 - 4905
(2013/05/09)
-
- Synthesis of planar chiral [2.2]Paracyclophanyl imidazo[1,5-a[pyridinium salts for the rhodium-catalyzed asymmetric arylation
-
Several novel flexibility-restricted imidazo[1,5-a]pyridinium triflates (abbreviated as imidazolium salts) were synthesized from (4S p,13R p)-()-4-amino-13-bromo[2.2]paracyclophane and pyridylaldehyde. These imidazolium salts can be used as nitrogen-containing heterocyclic carbene precursors in asymmetric catalysis and here they are applied in the Rh-catalyzed asymmetric 1,2-addition of arylboronic acids to aldehydes. After optimizing the catalytic situations and testing a series of substrates, moderate enantioselectivity and good yield were obtained.
- Wang, Dengxia,Ma, Yudao,He, Fuyan,Duan, Wenzeng,Zhao, Lei,Song, Chun
-
p. 810 - 825
(2013/02/25)
-
- Catalytic asymmetric reduction of prochiral ketones with chiral β-amino alcohol N-Boranes and the corresponding tris(oxazaborolidine) borazines
-
Chiral β-amino alcohol-derived N-borane catalysts, namely noncyclic (2S)- and (2R)-2-amino-2-phenylethanol N-borane and their corresponding cyclic trimeric borazine derivatives, were synthesized and their catalytic activities in the asymmetric reduction of prochiral ketones were examined. Both the noncyclic and cyclic catalysts successfully catalyzed this reaction, giving the desired secondary alcohols in up to 82% isolated yield and with up to 80% enantioselectivity. The noncyclic catalyst was stable in aqueous and organic solvents, whereas the polycyclic borazine was stable only in nonprotic dry organic solvents. Georg Thieme Verlag Stuttgart, New York.
- Pinaka, Afroditi,Dimotikali, Dimitra,Chankvetadze, Bezhan,Papadopoulos, Kyriakos,Vougioukalakis, Georgios C.
-
p. 2401 - 2406
(2013/11/06)
-
- Synthesis of new alkoxy/sulfonate-substituted carbene precursors derived from [2.2]paracyclophane and their application in the asymmetric arylation of aldehydes
-
A series of novel planar chiral alkoxy/sulfonate-substituted carbene precursors have been designed and synthesized. They were used as N-heterocyclic carbene ligands in the Rh-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- Duan, Wenzeng,Ma, Yudao,Qu, Bo,Zhao, Lei,Chen, Jianqiang,Song, Chun
-
p. 1369 - 1375
(2013/01/15)
-
- A novel lipase enzyme panel exhibiting superior activity and selectivity over lipase B from Candida antarctica for the kinetic resolution of secondary alcohols
-
A novel, commercially available lipase enzyme panel performing kinetic bioresolutions of a number of secondary alcohols is reported. The secondary alcohols that have been chosen are known from the literature to be particularly challenging substrates to resolve. Following initial screening, four co-solvents were investigated for each lead enzyme in an effort to assess their tolerance to common organic solvents. The superiority of these novel enzymes over lipase B from Candida antarctica (CALB) has been demonstrated.
- O'Neill, Maeve,Beecher, Denis,Mangan, David,Rowan, Andrew S.,Monte, Agnieszka,Sroka, Stefan,Modregger, Jan,Hundle, Bhupinder,Moody, Thomas S.
-
experimental part
p. 583 - 586
(2012/08/13)
-
- PROCESS FOR PRODUCING OPTICALLY ACTIVE ALCOHOL
-
Disclosed is a method for producing an optically active alcohol including reacting a titanium compound, an aromatic magnesium compound and a carbonyl compound in the presence of an optically active biphenol compound having a predetermined structure and an ether compound having a predetermined structure.
- -
-
-
- METHOD FOR SYNTHESIS OF SECONDARY ALCOHOLS
-
A method for synthesis of secondary alcohols is provided for pharmaceutical secondary alcohol by addition of organoboronic acids with aldehydes in presence of the cobalt ion and bidentate ligands as the catalyst. In addition, an enantioselective synthesis method for secondary alcohols is also herein provided in the present invention. The present invention has advantages in using less expensive cobalt ion and commercially available chiral ligands as the catalyst, wide scope of organoboronic acids and aldehydes compatible with this catalytic reaction and achieving excellent yields and/or enantiomeric excess.
- -
-
Page/Page column 3
(2012/06/16)
-
- CuII-catalyzed asymmetric hydrosilylation of diaryl- and aryl heteroaryl ketones: Application in the enantioselective synthesis of orphenadrine and neobenodine
-
With certain amounts of sodium tert-butoxide and tert-butanol as additives, catalytic amounts of an inexpensive and easy-to-handle copper source Cu(OAc)2·H2O, a commercially available and air-stable non-racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction of a broad spectrum of prochiral diaryl and aryl heteroarylketones in air, in high yields and with good to excellent enantioselectivities (up to 96 %). In particular, the practical viability of this process was evinced by its successful applications in the asymmetric synthesis of optically enriched potent antihistaminic drugs orphenadrine and neobenodine. Copyright
- Sui, Yao-Zong,Zhang, Xi-Chang,Wu, Jun-Wen,Li, Shijun,Zhou, Ji-Ning,Li, Min,Fang, Wenjun,Chan, Albert S. C.,Wu, Jing
-
supporting information; experimental part
p. 7486 - 7492
(2012/07/27)
-
- Asymmetric hydrosilylation of ketones catalyzed by complexes formed from trans-diaminocyclohexane-based diamines and diethylzinc
-
Chiral acyclic and macrocyclic amines derived from trans-1,2- diaminocyclohexane in complexes with diethylzinc efficiently catalyze asymmetric hydrosilylation of aryl-alkyl and aryl-aryl ketones with enantiomeric excess of the product up to 86 %. A trianglamine ligand with a cyclic structure or the presence of an additional coordinating group increases the enantioselectivity of the reaction, in comparison with catalysis by a simple acyclic N,N′-dibenzyl-1,2-diaminocyclohexane ligand. In addition, the effect of the asymmetric activation of the catalyst by a variety of alcohols and diols is studied.
- Gajewy, Jadwiga,Gawronski, Jacek,Kwit, Marcin
-
experimental part
p. 1045 - 1054
(2012/09/22)
-
- Ephedrine-based diselenide: A promiscuous catalyst suitable to mimic the enzyme glutathione peroxidase (GPx) and to promote enantioselective C-C coupling reactions
-
The ephedrine-based diselenide appears as a new promiscuous catalyst, able to generate optically active alcohols by addition of organozinc to aldehydes (up to 97% ee), and shows powerful GPx like activity, reducing H2O 2 to water in only 16.33 min (eleven times faster than PhSeSePh).
- Soares, Letiére C.,Alberto, Eduardo E.,Schwab, Ricardo S.,Taube, Paulo S.,Nascimento, Vanessa,Rodrigues, Oscar E. D.,Braga, Antonio L.
-
supporting information; experimental part
p. 6595 - 6599
(2012/09/08)
-
- Asymmetric additive-free aryl addition to aldehydes using perhydrobenzoxazines as ligands and boroxins as aryl source
-
A highly efficient enantioselective aryl addition to aldehydes using boroxins as aryl source and conformationally restricted perhydro-1,3- benzoxazines as ligands is reported. Both enantiomeric forms of chiral arylphenylmethanols and 1,1′-disubstituted diarylmethanols are afforded with excellent yields and enantioselectivities using the same ligand by means of an appropriate combination of boroxin and aromatic aldehyde. The enantiocontrol is not significantly influenced by electronic effects or steric hindrance, even with substituted boroxins. Very homogeneous ee's are reached when substituted arylboroxins are employed, without the use of any class of additive or pre-treatment.
- Infante, Rebeca,Nieto, Javier,Andres, Celia
-
experimental part
p. 6691 - 6699
(2011/11/04)
-
