- Synthesis of Citronellal by RhI-Catalysed Asymmetric Isomerization of N,N-Diethyl-Substituted Geranyl- and Nerylamines or Geraniol and Nerol in the Presence of Chiral Diphosphino Ligands, under Homogeneous and Supported Conditions
-
For the asymmetric isomerization of geranyl- or neryldiethylamine (( E)- or(Z)-1, resp.) and allyl alcohols geraniol or nerol ((E)- or (Z)-2, resp.) to citronellal (4) in the presence of a [RhI(ligand)cycloocta-1,5-diene)]- catalyst, the atropic ligands 5-11 are compared under homogeneous and polymer-supported conditions with the non-C2-symmetrical diphosphino ferrocene ligands 12-16. The tBu-josiphos ligand 13 or daniphos ligand 19, available in both antipodal series, already catalyse the reaction of (E)-1 at 20 deg (97 percent e.e.) and favourably compare with the binap ligand 5 (see Table 1). Silica-gel- or polymer-supported diphosphino ligands usually afford similar selectivity as compared to the corresponding ligands applied under homogeneous conditions, but are generally less reactive. In this context, a polymer-supported ligand of interest is the polymer-anchored binap (R)-6, in terms of reactivity, selectivity, and recoverability, with a turnover of more than 14400.
- Chapuis, Christian,Barthe, Michel,Laumer, Jean-Yves de Saint
-
-
Read Online
- Chiral 3D open-framework material Ni(D-cam)(H2O)2 used as GC stationary phase
-
Metal-organic frameworks (MOFs) have been explored for analytical applications because of their outstanding properties such as high surface areas, flexibility and specific structure features, especially for chromatography application in recent years. In this work, a chiral MOF Ni(D-cam)(H 2O)2 with unusual integration of molecular chirality, absolute helicity, and 3-D intrinsic chiral net was chosen as stationary phase to prepare Ni(D-cam)(H2O)2-coated open tubular columns for high-resolution gas chromatographic (GC) separation. Two fused-silica open tubular columns with different inner diameters and lengths, including column A (30 m × 250 μm i.d.) and column B (2 m × 75 μm i.d.), were prepared via a dynamic coating method. The chromatographic properties of the two columns were investigated using n-dodecane as the analyte at 120 °C. The number of theoretical plates (plates/m) of the two metal-organic framework (MOF) columns was 1300 and 2750, respectively. The racemates, isomer and linear alkanes mixture were used as analytes for evaluating the separation properties of Ni(D-cam)(H2O)2-coated open tubular columns. The results showed that the columns offered good separations of isomer and linear alkanes mixture, especially racemates. Chirality 26:27-32, 2013. 2013 Wiley Periodicals, Inc.
- Xie, Shengming,Wang, Bangjin,Zhang, Xinhuan,Zhang, Junhui,Zhang, Mei,Yuan, Liming
-
-
Read Online
- Asymmetric cleavage of chiral α,β-ethylenic acetals by organolithium reagents
-
,β-Ethylenic chiral acetals react regio- and stereoselectively with organolithium reagents. The obtained enol ether may be hydrolyzed into a chiral β-disubstituted aldehyde.
- Alexakis, Alexandre,Mhamdi, Farida,Lagasse, Franz,Mangeney, Pierre
-
-
Read Online
- Investigating the Structure-Reactivity Relationships Between Nicotinamide Coenzyme Biomimetics and Pentaerythritol Tetranitrate Reductase
-
Ene reductases (ERs) are attractive biocatalysts in terms of their high enantioselectivity and expanded substrate scope. Recent works have proved that synthetic nicotinamide coenzyme biomimetics (NCBs) can be used as easily accessible alternatives to natural cofactors in ER-catalyzed reactions. However, the structure-reactivity relationships between NCBs and ERs and influence factors are still poorly understood. In this study, a series of C-5 methyl modified NCBs were synthesized and tested in the PETNR-catalyzed asymmetric reductions. The physicochemical properties of these NCBs including electrochemical properties, stability, and kinetic behavior were studied in detail. The results showed that hydrophobic interaction caused by the introduced methyl group contributed to the stabilization of binding conformation in enzyme active site, resulting in comparable catalytic activity with that of NADPH. Molecular dynamics and steered molecular dynamics simulations were further performed to explain the binding mechanism between PETNR and NCBs, which revealed that stable catalytic conformation, appropriate donor-acceptor distance and angle, as well as free dissociation energy are important factors affecting the activity of NCBs. (Figure presented.).
- Tan, Zhuotao,Han, Yaoying,Fu, Yaping,Zhang, Xiaowang,Xu, Mengjiao,Na, Qi,Zhuang, Wei,Qu, Xudong,Ying, Hanjie,Zhu, Chenjie
-
p. 103 - 113
(2021/10/07)
-
- Chemoselective γ-Oxidation of β,γ-Unsaturated Amides with TEMPO
-
A chemoselective and robust protocol for the γ-oxidation of β,γ-unsaturated amides is reported. In this method, electrophilic amide activation, in a rare application to unsaturated amides, enables a regioselective reaction with TEMPO resulting in the title products. Radical cyclisation reactions and oxidation of the synthesised products highlight the synthetic utility of the products obtained.
- Heindl, Sebastian,Lemmerer, Miran,Malzer, Nicolas,Matyasovsky, Ján,Maulide, Nuno,Riomet, Margaux
-
supporting information
p. 19123 - 19127
(2021/07/26)
-
- Multicatalytic approach to one-pot stereoselective synthesis of secondary benzylic alcohols
-
One-pot procedures bear the potential to rapidly build up molecular complexity without isolation and purification of consecutive intermediates. Here, we report multicatalytic protocols that convert alkenes, unsaturated aliphatic alcohols, and aryl boronic acids into secondary benzylic alcohols with high stereoselectivities (typically >95:5 er) under sequential catalysis that integrates alkene cross-metathesis, isomerization, and nucleophilic addition. Prochiral allylic alcohols can be converted to any stereoisomer of the product with high stereoselectivity (>98:2 er, >20:1 dr).
- Casnati, Alessandra,Lichosyt, Dawid,Lainer, Bruno,Veth, Lukas,Dydio, Pawe?
-
supporting information
p. 3502 - 3506
(2021/05/10)
-
- Chiral amorphous metal–organic polyhedra used as the stationary phase for high-resolution gas chromatography separations
-
Herein, we describe a new chiral amorphous metal–organic polyhedra used as the stationary phase for high-resolution gas chromatography (GC). The chiral stationary phase was coated onto a capillary column via a dynamic coating process and investigated for a variety of compounds. The experimental results showed that the chiral stationary phase exhibits good selectivity for linear alkanes, linear alcohols, polycyclic aromatic hydrocarbons, isomers, and chiral compounds. In addition, the column has the advantages of high column efficiency and short analysis time. The present work indicated that amorphous metal–organic polyhedra have great potential for application as a new type of stationary phase for GC.
- Tang, Bo,Sun, Chenyu,Wang, Wei,Geng, Lina,Sun, Liquan,Luo, Aiqin
-
p. 1178 - 1185
(2020/07/09)
-
- Method for preparing optically active citronellal, and catalyst used in method
-
The invention provides a method for preparing optically active citronellal, and a catalyst for the method. The method comprises: in the presence of a catalyst, asymmetrically hydrogenating citral represented by a formula (I) and/or geranial represented by a formula (II) to prepare optically active R-citronellal represented by a formula (III), wherein the catalyst comprises rhodium as a catalytically active transition metal, a chiral bidentate diphosphine ligand, and basic alumina. According to the present invention, the catalytic stability of an optically active transition metal catalyst for asymmetric hydrogenation of homogeneous catalysis can be significantly improved without introducing of carbon monoxide so as to achieve high turnover number.
- -
-
Paragraph 0057-0558; 0073-0078
(2020/04/22)
-
- Method for isomerizing nerol or geraniol to synthesize chiral citronellal from
-
The invention provides a method for isomerizing nerol or geraniol to synthesize chiral citronellal, wherein the method comprises the steps: carrying out intramolecular allyl alcohol-aldehyde isomerization reaction on nerol or geraniol under the combined action of a water-soluble metal catalyst and alkali, to obtain the chiral citronellal product with high yield and high enantioselectivity. The method has the main advantages that a water-soluble phosphine ligand and a diamine ligand are combined, a water-soluble catalyst is creatively applied to an isomerization reaction of nerol or geraniol, catalysis is completed under the water-oil two-phase condition, after the reaction is completed, the catalyst is dissolved in a water phase, separation of the catalyst and the product can be achieved through simple phase splitting, repeated recycling of the catalyst can be achieved, and good economic benefits are achieved.
- -
-
Paragraph 0044-0073
(2020/04/29)
-
- Method for preparing optically active citronellal and catalyst system for method
-
The invention provides a method for preparing optically active citronellal and a catalyst system for the method. The method comprises the step that in the presence of a catalyst, neryl aldehyde shownin the formula (I) and/or geranial shown in the formula (II) are/is subjected to asymmetric hydrogenation to prepare optically active R-citronellal shown in the formula (III), and the catalyst comprises rhodium serving as a catalytic activity transition metal, a chiral bidentate diphosphine ligand and TiO2-loaded activated carbon. According to the method, the stereoselectivity of the reaction canbe remarkably improved, and the R-citronellal with high optical purity is obtained.
- -
-
Paragraph 0071-0085
(2020/05/05)
-
- Method for preparing R-citronellal
-
The invention provides a method for preparing R-citronellal. The method comprises the following steps: (1) synthesizing a chiral unsaturated compound containing cis-trans isomers from citral and azacyclo-phenyl chiral blocks; (2) crystallizing and separating the chiral unsaturated compound at a low temperature to obtain a cis-isomer and a trans-isomer; (3) performing asymmetric hydrogenation on the cis-isomer under the action of an R, R-type chiral metal catalyst to prepare an R-type chiral saturated compound; and/or carrying out asymmetric hydrogenation on the trans-isomer under the action ofan S, S-type chiral metal catalyst to prepare the R-type chiral saturated compound; and (4) carrying out hydrolysis reaction on the R-type chiral saturated compound to obtain R-citronellal. The citral used in the method does not need to be subjected to pretreatment separation, the total yield of a synthesis route is high, the product selectivity is extremely high due to the synergistic effect ofthe azacyclo-phenyl chiral blocks and the chiral metal catalyst, the atom utilization rate in the condensation and hydrolysis reaction process is high, and the method is suitable for industrial production of chiral citronellal.
- -
-
-
- Preparation method of optically active citronellal (by machine translation)
-
The preparation method of the optically active citronellal can significantly improve the catalytic stability, of the optically active transition metal catalyst for homogeneous catalysis to obtain, the optically active citronellal. which is obtained by reacting a transition metal compound with an optically active ligand containing two phosphorus atoms, and, or iron in the substrate material used for the asymmetric hydrogenation reaction . is prepared by reacting a transition metal compound with an optically active ligand containing two phosphorus atoms in the presence of a transition metal catalyst in the preparation method of the optically active citronellal with an asymmetric hydrogenation reaction in the presence of a transition metal catalyst to achieve a higher degree of peripheral speed, ≤6mgKOH/g/of the optically ≤50ppm. active citronellal. (by machine translation)
- -
-
Paragraph 0081; 0084
(2020/03/17)
-
- Method for preparing optically active citronellal (by machine translation)
-
The invention provides a method, for preparing optically active citronellal by reacting a transition metal catalyst with an asymmetric hydrogenation reaction, to obtain the optically active citronellal, wherein the substrate is neral and/or the vanillic, catalyst is obtained, by controlling the catalytic activity ≤500ppm of the asymmetric hydrogenation reaction substrate and remarkably improving the service life of the catalyst by controlling the asymmetric hydrogenation reaction substrate through oxidation . and ≤10ppm, or the aqueous chlorine, catalyst obtained by reacting the transition metal compound with the optically, active ligand containing .the two phosphorus atoms to obtain the optically active citronellal. (by machine translation)
- -
-
Paragraph 0085-0089
(2020/05/05)
-
- Method for synthesizing R-citronellal through water-oil two-phase asymmetric hydrogenation and catalyst used in the method
-
The invention provides a method for synthesizing R-citronellal through water-oil two-phase asymmetric hydrogenation and a catalyst used in the method, and particularly relates to a method for obtaining R-citronellal through asymmetric hydrogenation of neryl or geranial in a water-oil two-phase system by using hydrogen as a reducing agent and using a water-soluble metal complex as a catalyst. The method has the main advantages as follows: firstly, due to the use of the water-soluble phosphine ligand, the catalyst has good water solubility, the reaction is carried out in the water-oil two-phasesystem, and after the hydrogenation reaction is finished, the product R-citronellal and the catalyst can be separated through simple phase splitting; secondly, a small amount of lithium salt is addedinto the reaction system, so that the enantioselectivity of the product is improved; and finally, the catalyst dissolved in water can be recycled for multiple times, so that the cost of the catalyst is greatly reduced.
- -
-
Paragraph 0040-0094
(2020/04/17)
-
- Iridium-Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols Using MaxPHOX Ligands: Experimental and Theoretical Study
-
The asymmetric isomerization of primary allylic alcohols to chiral aldehydes using iridium-catalysts bearing P,N-MaxPHOX ligands has been studied. These catalysts can be fine-tuned as they present three different stereogenic centers to modulate both the reactivity and enantioselectivity of a family of different substrates. The experimental part is supported by a DFT study of the reaction mechanism, which provides new insights into the key steps of this transformation.
- Cabré, Albert,Gar?on, Martí,Gallen, Albert,Grisoni, Lorenzo,Grabulosa, Arnald,Verdaguer, Xavier,Riera, Antoni
-
p. 4112 - 4120
(2020/07/04)
-
- P-CHIRAL PHOSPHINE LIGANDS AND USE THEREOF FOR ASYMMETRIC SYNTHESIS
-
The present invention relates to chiral compounds with two optically active phosphorus atoms, chiral transition metal catalysts which comprise these compounds as ligands, a process for preparing the P-chiral compounds and processes for asymmetric synthesis using the chiral transition metal catalysts. The present invention specifically relates to a process for preparing an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of an optically active transition metal catalyst according to the invention. Yet more specifically, the present invention relates to a process for the asymmetric hydrogenation of citral, and also a process for preparing optically active menthol.
- -
-
Paragraph 0924; 0925; 0928
(2019/07/23)
-
- Method for methyl heptanone to synthetize chiral citronellal
-
The invention provides a method for methyl heptanone to synthetize chiral citronellal. The method includes the following steps: (1) performing methylenenation reaction on methyl heptanone and an organic tiron so that a 2,6-dimethyl-1,5-heptadiene intermediate with high yield; and (2) performing asymmetric hydroformylation on the heptadiene intermediate under the action of a homogeneous chiral rhodium catalyst so that a chiral citronellal product can be obtained. The main advantages of the method are as follows: the method is novel in synthetic method, a synthetic route is brief, and the chiralcitronellal product can be obtained by only two steps of reaction; the tiron can be used to perform the methylenenation reaction of the methyl heptanone, so that the 2,6-dimethyl-1,5-heptadiene can be obtained with high yield, and therefore, the method is higher than other existing known methods; and the method creatively utilizes the homogeneous chiral rhodium catalyst to realize the asymmetrichydroformylation of the 2,6-dimethyl-1,5-heptadiene, so that the method is high in reaction yield and excellent in stereoselectivity.
- -
-
Paragraph 0060-0071
(2019/05/08)
-
- Engineering the enantioselectivity of yeast old yellow enzyme Oye2Y in asymmetric reduction of (E/Z)-citral to (R)-citronellal
-
The members of the Old Yellow Enzyme (OYE) family are capable of catalyzing the asymmetric reduction of (E/Z)-citral to (R)-citronellal—a key intermediate in the synthesis of L-menthol. The applications of OYE-mediated biotransformation are usually hampered by its insufficient enantioselectivity and low activity. Here, the (R)-enantioselectivity of Old Yellow Enzyme from Saccharomyces cerevisiae CICC1060 (OYE2y) was enhanced through protein engineering. The single mutations of OYE2y revealed that the sites R330 and P76 could act as the enantioselectivity switch of OYE2y. Site-saturation mutagenesis was conducted to generate all possible replacements for the sites R330 and P76, yielding 17 and five variants with improved (R)-enantioselectivity in the (E/Z)-citral reduction, respectively. Among them, the variants R330H and P76C partly reversed the neral derived enantioselectivity from 32.66% e.e. (S) to 71.92% e.e. (R) and 37.50% e.e. (R), respectively. The docking analysis of OYE2y and its variants revealed that the substitutions R330H and P76C enabled neral to bind with a flipped orientation in the active site and thus reverse the enantioselectivity. Remarkably, the double substitutions of R330H/P76M, P76G/R330H, or P76S/R330H further improved (R)-enantioselectivity to >99% e.e. in the reduction of (E)-citral or (E/Z)-citral. The results demonstrated that it was feasible to alter the enantioselectivity of OYEs through engineering key residue distant from active sites, e.g., R330 in OYE2y.
- Ying, Xiangxian,Yu, Shihua,Huang, Meijuan,Wei, Ran,Meng, Shumin,Cheng, Feng,Yu, Meilan,Ying, Meirong,Zhao, Man,Wang, Zhao
-
-
- Monolacunary K8SiW11O39-Catalyzed Terpenic Alcohols Oxidation with Hydrogen Peroxide
-
Abstract: Lacunar potassium undecasilicotungstate salt catalyst was highly efficient in oxidation reactions of terpenic alcohols with hydrogen peroxide. Carbonylic products were selectively obtained from alcohols such as borneol, nerol, geraniol and β-citronellol. The K8SiW11O39 catalyst was synthesized in one pot reaction starting from precursor salts (KCl, Na2WO4, and Na2SiO3). The catalyst salt was characterized by FT-IR, TG/DSC, BET, XRD analyses and potentiometric titration. The main reaction parameters were assessed. Based on experimental data, a reaction pathway was proposed. In borneol oxidation, TON of 2720 was achieved, indicating the high catalytic activity. As far we know, it is the first time where the monolacunar catalyst is used without an additional introduction of metal transition into Keggin anion. A comparison of the catalytic performance of different lacunar silicotungstic acid salts exchanged with different cations was performed. The K8SiW11O39 catalyst was used without loss activity.
- da Silva, Márcio José,da Silva Andrade, Pedro Henrique,Ferreira, Sukarno Olavo,Vilanculo, Castelo Bandane,Oliveira, Cesar Macedo
-
p. 2516 - 2527
(2018/06/07)
-
- Enantio- A nd regioselective: Ene-reductions using F420H2-dependent enzymes
-
In the past decade it has become clear that many microbes harbor enzymes that employ an unusual flavin cofactor, the F420 deazaflavin cofactor. Herein we show that F420-dependent reductases (FDRs) can successfully perform enantio-, regio- A nd chemoselective ene-reductions. For the first time, we have demonstrated that F420H2-driven reductases can be used as biocatalysts for the reduction of α,β-unsaturated ketones and aldehydes with good conversions (>99%) and excellent regioselectivities and enantiomeric excesses (>99% ee). Noteworthily, FDRs typically display an opposite enantioselectivity when compared to the well established FMN-dependent Old Yellow Enzymes (OYEs).
- Mathew, Sam,Trajkovic, Milos,Kumar, Hemant,Nguyen, Quoc-Thai,Fraaije, Marco W.
-
p. 11208 - 11211
(2018/10/15)
-
- CuH-Catalyzed Asymmetric Reduction of α,β-Unsaturated Carboxylic Acids to β-Chiral Aldehydes
-
The copper hydride (CuH)-catalyzed enantioselective reduction of α,β-unsaturated carboxylic acids to saturated aldehydes is reported. This protocol provides a new method to access a variety of β-chiral aldehydes in good yields, with high levels of enantioselectivity and broad functional group tolerance. A reaction pathway involving a ketene intermediate is proposed based on preliminary mechanistic studies and density functional theory calculations.
- Zhou, Yujing,Bandar, Jeffrey S.,Liu, Richard Y.,Buchwald, Stephen L.
-
supporting information
p. 606 - 609
(2018/01/26)
-
- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE CARBONYL COMPOUNDS
-
The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral α,β-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): in which R1, R2: are identical or different and are C6- to C10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C1- to C6-alkyl, C3- to C6-cycloalkyl, C6- to C10-aryl, C1- to C6-alkoxy and amino;Z is a group CHR3R4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C1- to C6-alkyl, C3- to C6-cycloalkyl, C6- to C10-aryl, C1- to C6-alkoxy and amino, wherein R3 and R4 are as defined in the claims and the description.
- -
-
Paragraph 0199
(2018/03/25)
-
- A process for preparing optically active aldehyde or ketone method (by machine translation)
-
The present invention provides an asymmetric hydrogenation process for preparing optically active aldehyde or ketone of the method. The invention using transition metal catalyst and amino acid ester catalyst, so that the α, β - unsaturated aldehyde or ketone by selective asymmetric hydrogenation and the preparation of optically active aldehyde or ketone, reaction selectivity is greatly improved, the optical purity of the product can be as high as 99ee %. (by machine translation)
- -
-
Paragraph 0081; 0082; 0083; 0084; 0085; 0086-0099; 0102-0103
(2017/07/19)
-
- Microwave versus Conventional Light Activation of O-Radical Scission Processes
-
Domino or sequential processes initiated by cleavage of O radicals has led to the conversion of low-cost, readily available substrates into high-profit products. The optimization of these processes by using different activation sources (irradiation with v
- Carro, Carmen,Romero, Iván,Boto, Alicia
-
p. 373 - 380
(2017/01/24)
-
- A process for preparing optically active aldehyde or ketone method and catalyst preparation method
-
The invention provides a method for preparing optically active aldehyde or ketone by asymmetric hydrogenation and a preparation method of a catalyst thereof. The optically active aldehyde or ketone is prepared by using a homogeneous and optically active double transition metal catalyst and a chiral amino acid cocatalyst through asymmetric hydrogenation of alpha, beta-unsaturated aldehyde or ketone. The reaction pressure (absolute pressure) is 0.1-10MPa, preferably 5-8MPa; the reaction temperature is 25-90 DEG C; the catalyst is prepared from chiral multi-coordination phosphine-containing ligands and transition metals; chiral amino acid added to the reaction system serves as a cocatalyst; and the reaction selectivity is 95-99%, the conversion rate can reach 85-99.9%, and the optical purity of the product is 80-99ee%.
- -
-
Paragraph 0104; 0105; 0106; 0107-0119
(2017/04/07)
-
- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
-
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
-
p. 3301 - 3308
(2016/09/12)
-
- Method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation
-
The invention relates to a method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation in the technical field of chemical engineering. Under the effect of additives such as sodium iodide, tetraoctyl ammonium bromide and phenyltriethylammonium chloride, E-type and/or Z-type citral is catalyzed by chiral rhodium complex and asymmetrically hydrogenated into R or S chiral citronellal. In addition, E-type or Z-type citral can be catalyzed into chiral citronellal of the same required structure by changing chirality of chiral catalysts. Thus, citral of all structures can be completely converted into chiral rhodium of one required structure. The reaction method is mild in condition, easy and convenient to operate, capable of achieving good reaction yield and reaction efficiency and good in application effect.
- -
-
Paragraph 0049; 0050; 0051
(2016/10/07)
-
- A kind of preparation method of the optical active carbonyl compounds (by machine translation)
-
The invention discloses a kind of preparation method of the optical active carbonyl compounds, comprising the following steps: in the hand natural amine salt and under the catalysis of a transition metal catalyst, to hydrogen and a catalytic amount of dihydropyridine compound as the hydrogen source, α, β-unsaturated aldehyde or α, β-unsaturated ketone compound for asymmetric catalytic hydrogenation reaction, the obtained optically active carbonyl compounds. Mild reaction conditions of the method, the operation is simple, dihydropyridine compound amount is a catalytic amount, so that the target product is easily separated and purified from the reaction system, at the same time, can realize the recovery and reuse of the metal catalyst, in accordance with economic requirements. (by machine translation)
- -
-
Paragraph 0055; 0056; 0057; 0058
(2017/01/02)
-
- Metal-organic framework Co(D-cam)1/2(bdc)1/2(tmdpy) for improved enantioseparations on a chiral cyclodextrin stationary phase in gas chromatography
-
Initial efforts to combine a chiral metal-organic framework (MOF), Co(D-Cam)1/2(bdc)1/2(tmdpy) (D-Cam=D-camphoric acid, bdc=1,4-benzenedicarboxylic acid, tmdpy=4,4′-trimethylenedipyridine), with peramylated β-cyclodextrins to investigate whether the use of a MOF can enhance enantioseparations on a cyclodextrin stationary phase are reported. Compared with columns of peramylated β-cyclodextrin incorporated in a MOF containing sodium chloride, the column of peramylated β-cyclodextrin+MOF shows excellent selectivity for the recognition of racemates, and higher resolutions are achieved on the peramylated β-cyclodextrin+MOF stationary phase. Experimental results indicate that the use of Co(D-Cam) 1/2(bdc)1/2(tmdpy) can improve enantioseparations on peramylated β-cyclodextrins. This is the first report that chiral MOFs can improve enantioseparations on a chiral stationary phase for chromatography. Copyright
- Liu, Hong,Xie, Sheng-Ming,Ai, Ping,Zhang, Jun-Hui,Zhang, Mei,Yuan, Li-Ming
-
p. 1103 - 1108
(2014/11/07)
-
- Enantioselective isomerization of primary allylic alcohols into chiral aldehydes with the tol-binap/dbapen/ruthenium(II) catalyst
-
Efficient isomerization: The title reaction was catalyzed by the [RuCl 2{(S)-tol-binap}{(R)-dbapen}]/KOH system in ethanol at 25°C (see scheme). A series of E- and Z-configured aromatic and aliphatic allylic alcohols, including a simple primary alkyl-substituted compound (E)-3-methyl-2-hepten-1-ol, were transformed into the chiral aldehydes with at least 99 % ee. dbapen=2-dibutylamino-1-phenylethylamine, tol-binap=2,2′- bis(di-4-tolylphosphanyl)-1,1′-binaphthyl. Copyright
- Arai, Noriyoshi,Sato, Keisuke,Azuma, Keita,Ohkuma, Takeshi
-
supporting information
p. 7500 - 7504
(2013/07/26)
-
- METHOD FOR MANUFACTURING OPTICALLY ACTIVE MENTHOL
-
An object of the present invention is to provide a method for manufacturing an optically active menthol having fewer steps, which generates less environmentally polluting waste because a catalytic reaction is involved in all of the steps, and is capable of saving a production cost. The present invention relates to a method for manufacturing an optically active menthol, including the following steps: A-1) asymmetrically hydrogenating at least one of geranial and neral to thereby obtain an optically active citronellal, B-1) conducting a ring-closure reaction of the optically active citronellal in the presence of an acid catalyst to thereby obtain an optically active isopulegol, and C-1) hydrogenating the optically active isopulegol to thereby obtain an optically active menthol.
- -
-
Paragraph 0558
(2013/10/07)
-
- A dual catalyst system provides the shortest pathway for l-menthol synthesis
-
We have demonstrated that a combination of enantiopure 2- diarylmethylpyrrolidines and heterogeneous Pd/BaSO4 is an efficient catalytic system for the asymmetric hydrogenation of citral, specifically, a mixture of E-citral and Z-citral in any ratio, and that citronellal is obtained with high enantioselectivity. This dual catalyst system provides a new and more economical route to l-menthol.
- Maeda, Hironori,Yamada, Shinya,Itoh, Hisanori,Hori, Yoji
-
supporting information; experimental part
p. 1772 - 1774
(2012/03/09)
-
- Preparation of imidazolidin-4-ones and their evaluation as hydrolytically cleavable precursors for the slow release of bioactive volatile carbonyl derivatives
-
Imidazolidin-4-ones are suitable in practical applications as hydrolytically cleavable precursors for the controlled release of fragrant aldehydes and ketones. The corresponding profragrances were prepared by treating aliphatic carbonyl compounds with commercially available amino acid amines in the presence of a base to yield mixtures of diastereomers. The two diastereomers isolated from the reaction of glycinamide hydrochloride with (-)-menthone were separated by column chromatography. The absolute stereochemistry of the isomers was determined by NMR spectroscopy and confirmed by X-ray single crystal structure analysis. Under acidic conditions and in protic solvents, the two diastereomers slowly isomerized without releasing the ketone. The hydrolysis of the precursors was investigated by solvent extraction from buffered aqueous solutions and a cationic surfactant emulsion, as well as by dynamic headspace analysis after deposition onto a cotton surface. Generally, ketones were shown to be more readily released than aldehydes. Increasing the size of the substituents at C-5 decreased the rate of hydrolysis in solution and on the cotton surface. Glycinamide-based imidazolidin-4-ones were more efficient than the corresponding oxazolidin-4-ones or oxazolidines. Neither the release rates in solution, nor the hydrophobicity of the precursor structure (which influences deposition), nor the combination of these two parameters allowed easily predicting the performance of the delivery systems in application. Copyright
- Trachsel, Alain,Buchs, Barbara,Godin, Guillaume,Crochet, Aurelien,Fromm, Katharina M.,Herrmann, Andreas
-
supporting information; experimental part
p. 2837 - 2854
(2012/07/03)
-
- CATALYST FOR ASYMMETRIC HYDROGENATION AND METHOD FOR MANUFACTURING OPTICALLY ACTIVE CARBONYL COMPOUND USING THE SAME
-
The present invention provides a catalyst used for manufacturing an optically active carbonyl compound by selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which is insoluble in a reaction mixture, and a method for manufacturing the corresponding optically active carbonyl compound. Particularly, the invention provides a catalyst for obtaining an optically active citronellal useful as a flavor or fragrance, by selective asymmetric hydrogenation of citral, geranial or neral. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises: a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which the at least one metal is supported on a support; an optically active peptide compound; and an acid, and also relates to a method for manufacturing an optically active carbonyl compound using the same.
- -
-
Page/Page column 24-26
(2012/06/16)
-
- Asymmetric bioreduction of alkenes using ene-reductases YersER and KYE1 and effects of organic solvents
-
Asymmetric trans-bioreduction of activated alkenes by KYE1 from Kluyveromyces lactis and Yers-ER from Yersinia bercovieri, two ene-reductases from the Old Yellow Enzyme family, showed a broad substrate spectrum with a moderate to excellent degree of stereoselectivity. Both substrate- and enzyme-based stereocontrols were observed to furnish opposite stereoisomeric products. The effects of organic solvents on enzyme activity and stereoselectivity were outlined in this study, where two-phase systems hexane and toluene are shown to sustain bioreduction efficiency even at high organic solvent content.
- Yanto, Yanto,Winkler, Christoph K.,Lohr, Stephanie,Hall, Melanie,Faber, Kurt,Bommarius, Andreas S.
-
supporting information; experimental part
p. 2540 - 2543
(2011/06/25)
-
- Improved catalysts for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols based on charton analysis
-
An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relied on the preliminary mechanistic information available, and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation. Sterically unbiased chiral aldehydes that were not accessible previously have been obtained with high levels of enantioselectivity, thus validating the initial hypothesis regarding the selected ligand-design elements. A rationale for the high enantioselectivities achieved in most cases is also presented. Achieving enantioselectivity: An improved generation of chiral cationic iridium catalysts for the asymmetric isomerization of primary allylic alcohols is disclosed. The design of these air-stable complexes relies on preliminary mechanistic information and on Charton analyses using two preceding generations of iridium catalysts developed for this highly challenging transformation (see figure).
- Mantilli, Luca,Gerard, David,Torche, Sonya,Besnard, Celine,Mazet, Clement
-
supporting information; experimental part
p. 12736 - 12745
(2011/02/21)
-
- Towards preparative-scale, biocatalytic alkene reductions
-
Simple strategies for using alkene reductase enzymes to produce gram-scale quantities of both (R)- and (S)-citronellal have been developed. The methodology is easily accessible to non-specialist laboratories, allowing alkene reductases to be added to the toolbox of routine synthetic transformations.
- Bougioukou, Despina J.,Walton, Adam Z.,Stewart, Jon D.
-
body text
p. 8558 - 8560
(2011/01/03)
-
- Characterization of xenobiotic reductase A (XenA): Study of active site residues, substrate spectrum and stability
-
Xenobiotic reductase A (XenA) has broad catalytic activity and reduces various α,β-unsaturated and nitro compounds with moderate to excellent stereoselectivity. Single mutants C25G and C25V are able to reduce nitrobenzene, a non-active substrate for the wild type, to produce aniline. Total turnover is dominated by chemical rather than thermal instability. The Royal Society of Chemistry 2010.
- Yanto, Yanto,Yu, Hua-Hsiang,Hall, Melanie,Bommarius, Andreas S.
-
scheme or table
p. 8809 - 8811
(2011/02/28)
-
- ALUMINIUM COMPLEXES AND USE THEREOF AS A CATALYST IN INTRAMOLECULAR RING CLOSURE REACTIONS
-
To provide a process for increasing the proportion of an optical isomer of not only a compound having a closed ring but also a compound not having a closed ring when an optical isomer mixture of a compound having both a formyl group and a double bond capable of causing a carbonyl-ene ring closing reaction in the same molecule is subjected to a ring closing reaction. A process for increasing the proportion of an optical isomer characterized by subjecting an optical isomer mixture of a compound having both a formyl group and a double bond capable of causing a carbonyl-ene ring closing reaction in the same molecule to a ring closing reaction in the presence of a predetermined aluminum complex represented by the general formula: [All(L1)l(L2)m(Lh)n]k.
- -
-
Page/Page column 48-49
(2010/08/05)
-
- ALUMINIUM COMPLEXES AND USE THEREOF AS A CATALYST IN INTRAMOLECULAR RING CLOSURE REACTIONS
-
To provide a process for increasing the proportion of an optical isomer of not only a compound having a closed ring but also a compound not having a closed ring when an optical isomer mixture of a compound having both a formyl group and a double bond capable of causing a carbonyl-ene ring closing reaction in the same molecule is subjected to a ring closing reaction. A process for increasing the proportion of an optical isomer characterized by subjecting an optical isomer mixture of a compound having both a formyl group and a double bond capable of causing a carbonyl-ene ring closing reaction in the same molecule to a ring closing reaction in the presence of a predetermined aluminum complex represented by the general formula: [Al2(L1)n(L2)3-n]m.
- -
-
Page/Page column 44-45
(2010/08/05)
-
- METHOD FOR PRODUCING OPTICALLY ACTIVE, RACEMIC MENTHOL
-
The present invention relates to a particularly economic overall method for producing menthol, specifically for producing optically active, essentially enantiomerically and diastereomerically pure L-menthol and racemic menthol, starting from the starting material citral which is available inexpensively on an industrial scale. The method comprises the following steps a.1) catalytic hydrogenation of neral and/or geranial to give citronellal, b.1) cyclization of citronellal to isopulegol in the presence of an acidic catalyst, c.1) purification of isopulegol by crystallization and d.1) catalytic hydrogenation of isopulegol to give menthol.
- -
-
Page/Page column 38
(2010/10/19)
-
- CATALYST FOR ASYMMETRIC HYDROGENATION
-
This invention aims at providing a catalyst for producing an optically active aldehyde or an optically active ketone, which is an optically active carbonyl compound, by carrying out selective asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, particularly a catalyst which is insoluble in a reaction mixture for obtaining optically active citronellal which is useful as a flavor or fragrance, by carrying out selective asymmetric hydrogenation of citral, geranial or neral; and a method for producing a corresponding optically active carbonyl compound. The invention relates to a catalyst for asymmetric hydrogenation of an α,β-unsaturated carbonyl compound, which comprises a powder of at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table, or a metal-supported substance in which at least one metal selected from metals belonging to Group 8 to Group 10 of the Periodic Table is supported on a support, an optically active cyclic nitrogen-containing compound and an acid.
- -
-
Page/Page column 59
(2010/12/31)
-
- METHOD FOR SYNTHESIZING OPTICALLY ACTIVE CARBONYL COMPOUNDS
-
The present invention relates to a process for preparing optically active carbonyl compounds by asymmetrically hydrogenating α,β-unsaturated carbonyl compounds in the presence of optically active transition metal catalysts which are soluble in the reaction mixture and have at least one carbon monoxide ligand, the optically active catalyst which has at least one carbon monoxide ligand and is to be used in each case being prepared by pretreating a catalyst precursor with a gas mixture comprising carbon monoxide and hydrogen and the asymmetric hydrogenation being performed in the presence of carbon monoxide supplied additionally to the reaction mixture.
- -
-
Page/Page column 19
(2010/06/22)
-
- The substrate spectra of pentaerythritol tetranitrate reductase, morphinone reductase, N-ethylmaleimide reductase and estrogen-binding protein in the asymmetric bioreduction of activated alkenes
-
Four flavoproteins from the old yellow enzyme (OYE) family, pentaerythritol tetranitrate (PETNR) reductase, N-ethylmaleimide reductase (NEMR), morphinone reductase (MorR) and estrogen-binding protein (EBP1), exhibited a broad substrate tolerance by accepting conjugated enals, enones, imides, dicarboxylic acids and esters, as well as a nitroalkene and therefore can be employed for the asymmetric bioreduction of carbon-carbon double (C=C) bonds. In particular, morphinone reductase and estrogen-binding protein often showed a complementary stereochemical preference in comparison to that of previously investigated OYES.
- Mueller, Nicole J.,Stueckler, Clemens,Hauer, Bernhard,Baudendistel, Nina,Housden, Hazel,Bruce, Neil C.,Faber, Kurt
-
experimental part
p. 387 - 394
(2010/06/11)
-
- Expanded scope for the iridium-catalyzed asymmetric isomerization of primary allylic alcohols using readily accessible second-generation catalysts
-
A second generation of chiral (P,N)-iridium catalysts - readily accessible from inexpensive l-serine - displays expanded scope for the asymmetric isomerization of primary allylic alcohols.
- Mantilli, Luca,Mazet, Clement
-
supporting information; experimental part
p. 445 - 447
(2010/04/04)
-
- A new regeneration system for oxidized nicotinamide cofactors
-
A novel regeneration system for oxidized nicotinamide cofactors (NAD + and NADP+) is presented. By combining 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS)-catalyzed oxidation of NAD(P)H with laccase-catalyzed utilization of molecular oxygen as terminal oxidant, a simple chemo-enzymatic NAD(P)+ regeneration method is achieved. Thus, the advantages of both worlds, chemical oxidation of reduced nicotinamide cofactors and laccase-catalyzed utilization of oxygen from air are combined in a simple and generally applicable new approach for biooxidation catalysis. This new application of the well-known laccase-mediator system (LMS) is successfully used to promote alcohol dehydrogenase-catalyzed oxidation reactions of primary and secondary alcohols. Already under non-optimized conditions, high turnover numbers of > 300 and > 16000 were obtained for the nicotinamide cofactor and ABTS, respectively. In this communication, we present the proofof-principle and initial characterization of the proposed new regeneration system.
- Aksu, Seda,Arends, Isabel W.C.E.,Hollmann, Frank
-
supporting information; experimental part
p. 1211 - 1216
(2010/03/01)
-
- ORGANIC SALTS AND METHOD FOR PRODUCING CHIRAL ORGANIC COMPOUNDS
-
The invention relates to a method for producing chiral organic compounds by asymmetric catalysis, using ionic catalysts comprising a chiral catalyst anion. The claimed method is suitable for reactions which are carried out over cationic intermediate stages, such as iminium ions or acyl pyridinium ions. The invention enables the production of chiral compounds with high ee values, that until now could only be obtained by means of costly purification methods.
- -
-
Page/Page column 6
(2009/02/11)
-
- Asymmetrie reduction of activated alkenes by pentaerythritol tetranitrate reductase: Specificity and control of stereochemical outcome by reaction optimisation
-
We show that pentaerythritol tetranitrate reductase (PETNR), a member of the 'ene' reductase old yellow enzyme family, catalyses the asymmetric reduction of a variety of industrially relevant activated α,β-unsaturated alkenes including enones, enals, maleimides and nitroalkenes. We have rationalised the broad substrate specificity and stereochemical outcome of these reductions by reference to molecular models of enzyme-substrate complexes based on the crystal complex of the PETNR with 2cyclohexenone 4a. The optical purity of products is variable (49-99% ee), depending on the substrate type and nature of substituents. Generally, high enantioselectivity was observed for reaction products with stereogenic centres at Cβ (>99% ee). However, for the substrates existing in two isomeric forms (e.g., citral 11a or nitroalkenes 18-19a), an enantio-divergent course of the reduction of E/Z-forms may lead to lower enantiopurities of the products. We also demonstrate that the poor optical purity obtained for products with stereogenic centres at Ca is due to non-enzymatic racemisation. In reactions with ketoisophorone 3a we show that product racemisation is prevented through reaction optimisation, specifically by shortening reaction time and through control of solution pH. We suggest this as a general strategy for improved recovery of optically pure products with other biocatalytic conversions where there is potential for product racemisation.
- Fryszkowska, Anna,Toogood, Helen,Sakuma, Michiyo,Gardiner, John M.,Stephens, Gill M.,Scrutton, Nigel S.
-
supporting information; experimental part
p. 2976 - 2990
(2010/03/25)
-
- Asymmetric bioreduction of activated C=C bonds using Zymomonas mobilis NCR enoate reductase and old yellow enzymes OYE 1-3 from yeasts
-
The asymmetric bioreduction of C=C-bonds bearing an electron-withdrawing group, such as an aldehyde, ketone, imide, nitro, carboxylic acid, or ester moiety by a novel enoate reductase from Zymomonas mobilis and Old Yellow Enzymes OYE 1-3 from yeasts furnished the corresponding saturated products in up to >99%ee. Depending on the substrate type, stereocontrol was achieved by variation of the substrate structure, by switching the (E/Z) geometry of the alkene or by choice of the appropriate enzyme. This substrate- or enzyme-based stereocontrol allowed access to the opposite enantiomeric products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Hall, Melanie,Stueckler, Clemens,Hauer, Bernhard,Stuermer, Rainer,Friedrich, Thomas,Breuer, Michael,Kroutil, Wolfgang,Faber, Kurt
-
scheme or table
p. 1511 - 1516
(2009/04/11)
-
- Asymmetric bioreduction of activated alkenes using cloned 12-oxophytodienoate reductase isoenzymes OPR-1 and OPR-3 from Lycopersicon esculentum (tomato): A striking change of stereoselectivity
-
(Chemical Equation Presented) Tomato source: 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from tomato possess a broad substrate spectrum for the asymmetric bioreduction of α,β-unsaturated enals, enones, dicarboxylic acids, and N-substituted male-imides (see scheme). Stereocomplementary behavior of both isoenzymes was observed in the reduction of a nitroalkene that led to the formation of opposite stereoisomers in high enantiomeric excess.
- Hall, Melanie,Stueckler, Clemens,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
-
p. 3934 - 3937
(2008/03/11)
-
- METHOD FOR THE PRODUCTION OF MENTHOL
-
The invention relates to a method for producing optically active menthol from geraniol, nerol, or mixtures of geraniol and nerol by a) enantioselectively hydrogenating geraniol, nerol, or mixtures of geraniol and nerol to optically active citronellol, b) reacting the obtained optically active citronellol to optically active citronellal, c) cyclizing the obtained optically active citronellal to a mixture containing optically active isopulegol, and d) eliminating optically active isopulegol from the obtained mixture and hydrogenating the same to optically active menthol or hydrogenating the optically active isopulegol contained in the mixture to optically active menthol and eliminating the obtained optically active menthol from the mixture obtained as hydrogenation product.
- -
-
Page/Page column 23
(2008/06/13)
-
- Asymmetric whole-cell bioreduction of an α,β-unsaturated aldehyde (citral): competing prim-alcohol dehydrogenase and C-C lyase activities
-
Asymmetric bioreduction of (E/Z)-3,7-dimethyl-2,6-octadienal (citral) using the enoate reductase activity of whole cells of yeasts, bacteria and fungi, gave the α,β-saturated aldehyde (R)-3,7-dimethyl-6-octenal (citronellal), which constitutes an important flavour component, in up to ≥95% ee. Depending on the microorganism, various amounts of prim-alcohols (nerol/geraniol and citronellol) were formed due to the action of competing prim-alcohol dehydrogenases. Citral lyase activity-leading to the loss of a C2-fragment (acetaldehyde) forming sulcatone-and oxidation of the aldehyde moiety yielding the carboxylic acid (geranic/neric acid) were detected as additional metabolic activities.
- Hall, Melanie,Hauer, Bernhard,Stuermer, Rainer,Kroutil, Wolfgang,Faber, Kurt
-
p. 3058 - 3062
(2007/10/03)
-