Enantioselective addition of diethylzinc to benzaldehyde catalyzed by an organometallic Ti(IV) compound and a xylose derivative

Parada, José; Herrera, Juan P; Pedraza, A.

doi:10.1590/s0103-50532009000100013

Cited by 3 publications

(9 citation statements)

References 7 publications

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“…Derivative 2 gave higher enantioselectivity than carbohydrate 1, reaching maximum enantioselectivity (57% ee) with 10% mol of derivative 2 (entry13, Table 1) A smaller (5% mol) or larger (20% mol) amount of derivative 2 slightly decreased enantioselectivity in both cases, reaching 48% ee at 6 h reaction time (entry 12, Table 1), i.e., than that with the Ti(IV)-carbohydrate 1 system. These results are similar to those obtained with the Ti(IV)-derivative 3 catalytic system, which gave a maximum enantiomeric excess of 45%, 15 indicating that for maximum ensntioselectivity, the Ti(IV)-carbohydrate catalytic system must contain a bidentate ligand (2 or 3). The possible dinuclear catalyst, Ti(IV)-carbohydrate (2 or 3) (Scheme 1) generated within the reaction should be rigid, enhancing steric and electronic factors favoring a predominant configuration of the resulting 1-phenyl-1-propanol.…”

Section: Methodssupporting

confidence: 82%

“…The solvent was CH 2 Cl 2 , previously found to be the most adequate for the Ti(IV) plus derivative 3 system). 15 In this preliminary study it was also shown that catalysis was effective at room temperature and reaction…”

Section: Resultsmentioning

confidence: 86%

“…15 All the reactions under study show a high conversion of benzaldehyde to 1-phenyl-1-propanol with Ti(IV) and derivatives 1 or 2 ( Table 1). The yield was independent of the OH group arrangement or of the carbohydrate being a monodentate (1) or bidentate (2 and 3) ligand.…”

Section: Methodsmentioning

confidence: 92%

“…All the Ti(IV)-carbohydrate catalytic systems 1 or 2 preferably gave R 1-phenyl-1-propanol (Table 1), unlike that with the Ti(IV)-derivative 3 system, where the prevailing configuration of 1-phenyl-1-propanol is S, 15 indicating that in the Ti(IV)-carbohydrate (2 or 3) (Scheme 1) the arrangement of OH groups of carbohydrate (2 or 3) determines the configuration (R or S) of 1-phenyl-1-propanol.…”

Section: Methodsmentioning

confidence: 99%

“…[7][8][9][10][11][12][13][14] We have recently catalyzed the homogeneous selective addition of diethylzinc to benzaldehyde 15 . The catalyst was the mixture of 10% mol of a diol derivative of D-xylose (3) relative to the aldehyde with 1 equivalent of Ti(O i Pr) 4 .…”

Section: -356mentioning

confidence: 99%

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Enantioselective Addition of Diethyl Zinc to Benzaldehyde Catalyzed by Ti(iv) and Glucose Derivatives

Parada

Mendoza

Cisternas

et al. 2010

J. Chil. Chem. Soc.

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D-Glucose derivatives 1,2:5,6-di-O-isopropyline-a-D-glucofuranose (1) and 1,2-O-isopropyline-a-D-glucofuranose (2) with Ti(IV) are chiral catalysts in the addition of diethylzinc to benzaldehyde. The Ti(IV)-carbohydrate catalytic system is optimal with excess Ti(IV) and substoichiometric carbohydrate and 2 is the more active chiral catalyst probably because this derivative acts as a bidentate ligand in the proposed reaction. The arrangement of OH groups is crucial in determining the configuration of the alcohol product.

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Section: Methodssupporting

confidence: 82%

Section: Resultsmentioning

confidence: 86%

Section: Methodsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: -356mentioning

confidence: 99%

See 3 more Smart Citations

Enantioselective Addition of Diethyl Zinc to Benzaldehyde Catalyzed by Ti(iv) and Glucose Derivatives

Parada

Mendoza

Cisternas

et al. 2010

J. Chil. Chem. Soc.

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Optimization of Lipase-Catalyzed Enantioselective Production of 1-Phenyl 1-Propanol Using Response Surface Methodology

Soyer¹,

Bayraktar²,

Mehmetoǧlu³

2010

Preparative Biochemistry and Biotechnology

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Optically active 1-phenyl 1-propanol is used as a chiral building block and synthetic intermediate in the pharmaceutical industries. In this study, the enantioselective production of 1-phenyl 1-propanol was investigated systematically using response surface methodology (RSM). Before RSM was applied, the effects of the enzyme source, the type of acyl donor, and the type of solvent on the kinetic resolution of 1-phenyl 1-propanol were studied. The best results were obtained with Candida antartica lipase (commercially available as Novozym 435), vinyl laurate as the acyl donor, and isooctane as the solvent. In the RSM, substrate concentration, molar ratio of acyl donor to the substrate, amount of enzyme, temperature, and stirring rate were chosen as independent variables. The predicted optimum conditions for a higher enantiomeric excess (ee) were as follows: substrate concentration, 233 mM; molar ratio of acyl donor to substrate, 1.5; enzyme amount, 116 mg; temperature, 47 °C; and stirring rate, 161 rpm. A verification experiment conducted at these optimized conditions for maximum ee yielded 91% for 3 hr, which is higher than the predicted value of 83%. The effect of microwave on the ee was also investigated and ee reached 87% at only 5 min.

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Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

Ruiz¹,

Fierro²,

Reyes³

2010

J. Braz. Chem. Soc.

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A hidrogenação enantiosseletiva de piruvato de etila e de 1-fenil-1,2-propanodiona foi estudada a 298 K e sob 40 bar de H 2 sobre um catalisador de platina coloidal estabilizado com cinchonidina (CD) e suportado em sílica. O catalisador foi preparado por impregnação da platina coloidal em sílica, atingindo 1% em massa do metal no suporte. O colóide foi preparado a partir de uma solução aquosa de H 2 PtCl 6 estabilizada com diferentes quantidades de CD. O catalisador foi caracterizado por isotermas de adsorção-desorção de N 2 a 77 K e por XPS, XRD e TEM. As reações foram efetuadas em batelada em um reator de aço inoxidável, usando cicloexano como solvente e cinchonidina como modificador quiral. A adição de CD ao catalisador permite a estabilização e o controle do tamanho de partícula da platina, e também afeta o excesso enantiomérico (ee) do sistema, levando a um maior rendimento do produto com configuração R. A relação entre a concentração de CD adicionada in situ e a enantiosseletividade apresenta uma curva do tipo sino nas duas reações estudadas; este comportamento é um indicativo da importância da adsorção competitiva do modificador e do substrato na superfície do catalisador.The enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione was studied at 298 K and 40 bar of H 2 over colloidal Pt stabilized with cinchonidine (CD) and supported on silica. The catalysts were prepared by impregnation of colloidal Pt on SiO 2 , leading to a metal load close to 1 wt.%. The colloid was prepared from an aqueous solution of H 2 PtCl 6 and stabilized with different quantities of CD. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, XPS, XRD and TEM techniques. The reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. The addition of CD to the catalysts allows the stabilization and control of the platinum particle size and also affects the enantiomeric excess (ee) of the system, affording a higher proportion of the (R)-product. The relationship between the enantioselectivity and the CD concentration (added in situ) exhibits a bell type curve for both reactions, this being indicative of the importance of a competitive adsorption of the modifier and substrate on the catalyst surface.Keywords: Pt colloids, enantioselectivity, ethyl pyruvate, 1-phenyl-1,2-propanedione, cinchonidine IntroductionEnantioselective hydrogenation reactions are important tools to obtain fine chemicals used in pharmaceutical and food products.1-4 Thus, the synthesis of chiral compounds is of growing interest; among them, the hydrogenation of a-ketoesters and ketones is the most widely studied. [5][6][7][8][9][10][11][12][13][14][15] Since Orito et al. reported the enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate over cinchonidine-modified Pt catalysts with ee's up to 95%, many other research teams have evaluated the performance of their catalytic systems in this reaction. [16][17][18] Indeed, this is n...

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Enantioselective addition of diethylzinc to benzaldehyde catalyzed by an organometallic Ti(IV) compound and a xylose derivative

Cited by 3 publications

References 7 publications

Enantioselective Addition of Diethyl Zinc to Benzaldehyde Catalyzed by Ti(iv) and Glucose Derivatives

Enantioselective Addition of Diethyl Zinc to Benzaldehyde Catalyzed by Ti(iv) and Glucose Derivatives

Optimization of Lipase-Catalyzed Enantioselective Production of 1-Phenyl 1-Propanol Using Response Surface Methodology

Enantioselective hydrogenation of ethyl pyruvate and 1-phenyl-1,2-propanedione on catalysts prepared by impregnation of colloidal platinum on SiO2

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