- Copper-Catalyzed Decarboxylative Alkylselenation of Propiolic Acids with Se Powder and Epoxides
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A copper-catalyzed decarboxylative alkylselenation of propiolic acids with Se powder and epoxides leading to alkynyl selenides is developed. This protocol not only provides an approach to obtain alkynyl selenides with the formation of double C?Se bonds, but also expands the applicability of alkynyl carboxylic acid. (Figure presented.).
- Yao, Yujing,Wang, Caihong,Ma, Yunfei,Zhang, Jintao,Sun, Dong,Chen, Luya,Huang, Lehao,Wu, Ge
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- Ligand-Free Copper-Catalyzed Ullmann-Type C?O Bond Formation in Non-Innocent Deep Eutectic Solvents under Aerobic Conditions
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An efficient and novel protocol was developed for a Cu-catalyzed Ullmann-type aryl alkyl ether synthesis by reacting various (hetero)aryl halides (Cl, Br, I) with alcohols as active components of environmentally benign choline chloride-based eutectic mixtures. Under optimized conditions, the reaction proceeded under mild conditions (80 °C) in air, in the absence of additional ligands, with a catalyst [CuI or CuII species] loading up to 5 mol% and K2CO3 as the base, providing the desired aryloxy derivatives in up to 98 % yield. The potential application of the methodology was demonstrated in the valorization of cheap, easily available, and naturally occurring polyols (e. g., glycerol) for the synthesis of some pharmacologically active aryloxypropanediols (Guaiphenesin, Mephenesin, and Chlorphenesin) on a 2 g scale in 70–96 % yield. Catalyst, base, and deep eutectic solvent could easily and successfully be recycled up to seven times with an E-factor as low as 5.76.
- Capriati, Vito,García-álvarez, Joaquín,Marinò, Manuela,Perna, Filippo M.,Quivelli, Andrea Francesca,Vitale, Paola
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- An Amphiphilic (salen)Co Complex – Utilizing Hydrophobic Interactions to Enhance the Efficiency of a Cooperative Catalyst
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An amphiphilic (salen)Co(III) complex is presented that accelerates the hydrolytic kinetic resolution (HKR) of epoxides almost 10 times faster than catalysts from commercially available sources. This was achieved by introducing hydrophobic chains that increase the rate of reaction in one of two ways – by enhancing cooperativity under homogeneous conditions, and increasing the interfacial area under biphasic reaction conditions. While numerous strategies have been employed to increase the efficiency of cooperative catalysts, the utilization of hydrophobic interactions is scarce. With the recent upsurge in green chemistry methods that conduct reactions ‘on water’ and at the oil-water interface, the introduction of hydrophobic interactions has potential to become a general strategy for enhancing the catalytic efficiency of cooperative catalytic systems. (Figure presented.).
- Solís-Mu?ana, Pablo,Salam, Joanne,Ren, Chloe Z.-J.,Carr, Bronte,Whitten, Andrew E.,Warr, Gregory G.,Chen, Jack L.-Y.
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supporting information
p. 3207 - 3213
(2021/06/01)
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- Highly regio- and enantio-selective hydrolysis of two racemic epoxides by GmEH3, a novel epoxide hydrolase from Glycine max
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A novel epoxide hydrolase from Glycine max, designated GmEH3, was excavated based on the computer-aided analysis. Then, gmeh3, a GmEH3-encoding gene, was cloned and successfully expressed in E. coli Rosetta(DE3). Among the ten investigated rac-epoxides, GmEH3 possessed the highest and best complementary regioselectivities (regioselectivity coefficients, αS = 93.7% and βR = 97.2%) in the asymmetric hydrolysis of rac-m-chlorostyrene oxide (5a), and the highest enantioselectivity (enantiomeric ratio, E = 55.6) towards rac-phenyl glycidyl ether (7a). The catalytic efficiency (kcatS/KmS = 2.50 mM?1 s?1) of purified GmEH3 for (S)-5a was slightly higher than that (kcatR/KmR = 1.52 mM?1 s?1) for (R)-5a, whereas the kcat/Km (5.16 mM?1 s?1) for (S)-7a was much higher than that (0.09 mM?1 s?1) for (R)-7a. Using 200 mg/mL wet cells of E. coli/gmeh3 as the biocatalyst, the scale-up enantioconvergent hydrolysis of 150 mM rac-5a at 25 °C for 1.5 h afforded (R)-5b with 90.2% eep and 95.4% yieldp, while the kinetic resolution of 500 mM rac-7a for 2.5 h retained (R)-7a with over 99% ees and 43.2% yields. Furthermore, the sources of high regiocomplementarity of GmEH3 for (S)- and (R)-5a as well as high enantioselectivity towards rac-7a were analyzed via molecular docking (MD) simulation.
- Zhang, Chen,Li, Chuang,Zhu, Xiu-xiu,Liu, You-yi,Zhao, Jun,Wu, Min-chen
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p. 2795 - 2803
(2020/09/01)
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- Ultrasound Assisted the Synthesis of 1,3-Dioxolane Derivatives from the Reaction of Epoxides or 1,2-Diols with Various Ketones Using Graphene Oxide Catalyst
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Abstract: The main objective of this study concerns the sonochemical synthesis of 1,3-dioxolane derivatives using graphene oxide catalyst by applying two methods. In the first method, we described the synthesis of 1,3-dioxolane by ring-opening of epoxides in the presence of ketones catalyzed by graphene oxide (GO) under ultrasonic irradiation. In the second sonochemical procedure, we described the synthesis of 1,3-dioxolane derivatives by the reaction of 1,2-diols with ketones using same GO catalyst. Mild reaction conditions, high yields, short reaction times, reusability of catalyst and easy isolation of the products make the developed methods very useful. Graphic Abstract: [Figure not available: see fulltext.]
- Mirza-Aghayan, Maryam,Mohammadi, Marzieh,Ahmadi, Zahra,Boukherroub, Rabah
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p. 2959 - 2969
(2020/04/22)
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- MnIII Porphyrins: Catalytic Coupling of Epoxides with CO2 under Mild Conditions and Mechanistic Considerations
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A series of 5,10,15,20-tetrakis(2,3-dichlorophenyl)porphyrinate complexes of manganese(III) [MnIII(T2,3DCPP)X] with six different axial ligands (X=NO3 ?, AcO?, IO3 ?, Br?, Cl?, HO?) were investigated as catalysts in the cycloaddition reactions of CO2 and styrene oxide (SO), under mild conditions, i. e., atmospheric pressure and 60 °C. [MnIIIT(2,3DCPP)IO3] showed the best catalytic performance, selectively producing the respective cyclic carbonate from diverse epoxides using tetrabutylammonium bromide as a nucleophile source. Mechanistic considerations were inferred from electronic spectra and spectrophotometric titrations, showing that there are a series of equilibriums involved in the formation of the catalytic active species. Stability constants for the proposed equilibrium models were determined using SQUAD software. A catalytic cycle has been proposed based on those observations.
- Milani, Jorge L. S.,Meireles, Alexandre M.,Bezerra, Werberson A.,Martins, Dayse. C. S.,Cangussu, Danielle,das Chagas, Rafael P.
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p. 4393 - 4402
(2019/08/01)
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- A novel homochiral metal-organic framework with an expanded open cage based on (: R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl: synthesis, X-ray structure and efficient HPLC enantiomer separation
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A new homochiral metal-organic framework (MOF) with an expanded open cage based on the (R)-3,3′-bis(6-carboxy-2-naphthyl)-2,2′-dihydroxy-1,1′-binaphthyl ligand was synthesized and utilized as a novel chiral stationary phase for high-performance liquid chromatography. Twelve racemates including sec-alcohols, sulfoxides, epoxides, lactone, 1,3-dioxolan-2-one, and oxazolidinone were used as analytes for evaluating the separation properties of the chiral-MOF-packed column. Experimentally, the homochiral MOF offered good molecular recognition ability, which suggests good prospects for the application of chiral MOFs as stationary phases for enantioseparation.
- Tanaka, Koichi,Kawakita, Tomohiro,Morawiak, Maja,Urbanczyk-Lipkowska, Zofia
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p. 487 - 493
(2019/01/21)
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- An innovative synthesis pathway to benzodioxanes: The peculiar reactivity of glycerol carbonate and catechol
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A peculiar reactivity of glycerol carbonate (GlyC) as an innovative and highly reactive alkylating agent for phenolic compounds is investigated in this article. In particular, 2-hydroxymethyl-1,4-benzodioxane (HMB), a key intermediate for the pharmaceutical industry, has been selectively synthesized by the reaction of a slight excess of GlyC with catechol in the presence of a basic catalyst (NaOCH3, Na-mordenite, MgO), without requiring a reaction solvent. Both reagents have been quantitatively converted in just one hour at 170 °C with a HMB yield, up to 88%, in the presence of a homogeneous basic catalyst (NaOCH3). Notably, the main side product, the HMB isomer, may be an interesting intermediate for the synthesis of calone analogues, which are important scaffolds used in fragrances. A detailed mechanistic study, supported by kinetics, GC-MS, and HMBC NMR characterization, is also reported. Accordingly, this paper describes a completely innovative and greener synthesis pathway to benzodioxanes.
- Tabanelli,Giliberti,Mazzoni,Cucciniello,Cavani
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p. 329 - 338
(2019/01/28)
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- Enantioselective Resolution Copolymerization of Racemic Epoxides and Anhydrides: Efficient Approach for Stereoregular Polyesters and Chiral Epoxides
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Herein we report an efficient strategy for preparing isotactic polyesters and chiral epoxides via enantioselective resolution copolymerization of racemic terminal epoxides with anhydrides, mediated by enantiopure bimetallic complexes in conjunction with a nucleophilic cocatalyst. The chirality of both the axial linker and the diamine backbones of the ligand are responsible for the chiral induction of this kinetic resolution copolymerization process. The catalyst systems exhibit exceptional levels of enantioselectivity with a kinetic resolution coefficient exceeding 300 for various racemic epoxides, affording highly isotactic copolymers (selectivity factors of more than 300) with a completely alternating structure and low polydispersity index. Most of the produced isotactic polyesters are typical semicrystalline materials with melting temperatures in the range from 77 to 160 °C.
- Li, Jie,Ren, Bai-Hao,Wan, Zhao-Qian,Chen, Shi-Yu,Liu, Ye,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 8937 - 8942
(2019/06/11)
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- HETEROCYCLIC LIPXON ANALOGS AND USES THEROF
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The present invention relates to a compound of formula (I): wherein L is an optionally substituted heterocyclic group excluding unsubstituted monocyclic pyridine groups; wherein a is 0, 1 or 2; wherein R1 is H or with R2 is a bond; wherein R2 is an optionally substituted alkoxy or aryloxy group, or with R1 forms a bond; wherein R3 is an optionally substituted alkyl group; and wherein R4 is CH2, CMe2 or O. Such compounds may be used in the treatment or prophylaxis of a disease or condition in which inhibition of acute inflammation and/or promotion of its resolution and/or suppression of fibrosis.
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Page/Page column 103
(2018/03/09)
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- Calix[8]arene as New Platform for Cobalt-Salen Complexes Immobilization and Use in Hydrolytic Kinetic Resolution of Epoxides
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Eight cobalt-salen complexes have been covalently attached to a calix[8]arene platform through a flexible linker by a procedure employing Click chemistry. The corresponding well-defined catalyst proved its efficiency in the hydrolytic kinetic resolution (HKR) of various epoxides through an operative bimetallic cooperative activation, demonstrating highly enhanced activity when compared to its monomeric analogue. As an insoluble complex, this multisite cobalt-salen catalyst could be easily recovered and reused in successive catalytic runs. Products were isolated by a simple filtration with virtually no cobalt traces and without requiring a prior purification by flash chromatography.
- Abdellah, Ibrahim,Martini, Cyril,Dos Santos, Amandine,Dragoe, Diana,Guérineau, Vincent,Huc, Vincent,Schulz, Emmanuelle
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p. 4761 - 4767
(2018/10/02)
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- Raw and waste plant materials as sources of fungi with epoxide hydrolase activity. Application to the kinetic resolution of aryl and alkyl glycidyl ethers
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The by-products of olive oil production can be used as sources of microbial strains. Penicillium sp., Aspergillus terreus, Penicillium aurantiogriseum, Aspergillus tubingensis and Aspergillus niger were selected on the basis of their epoxide-hydrolyzing activity towards racemic rac-glycidyl phenyl ether. We studied the effect on enzymatic activity of adding styrene oxide to the growth medium. It induced the biosynthesis of epoxide hydrolases and reduced cell growth. The resolution capacity of the five fungi was tested on rac-glycidyl phenyl ether, rac-benzyl glycidyl ether, rac-1,2-epoxyhexane and rac-1,2-epoxyoctane. The resolution of rac-glycidyl phenyl ether by A. niger, rac-benzyl glycidyl ether by P. aurantiogriseum and A. terreus, rac-1,2-epoxyhexane by A. tubingensis and rac-1,2-epoxyoctane by A. terreus provided (S)-3-phenoxy-1,2-propanediol (45.1% yield, 51.4% ee), (R)-3-benzyloxy-1,2-propanediol (40.8% yield, 43.3% ee), (S)-3-benzyloxy-1,2-propanediol (45.4% yield, 45.6% ee), (R)-1,2-hexanediol (70.4% yield, 24.4% ee) and (R)-1,2-octanediol (21.4% yield, 27.5% ee), respectively. The (R)-enantiopreference of the epoxide hydrolases from P. aurantiogriseum is unprecedented.
- Dolcet, Marta,Torres, Mercè,Canela-Garayoa, Ramon
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- Asymmetric Hydrolytic and Aminolytic Kinetic Resolution of Racemic Epoxides using Recyclable Macrocyclic Chiral Cobalt(III) Salen Complexes
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New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)-propranolol and (R)-naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity. (Figure presented.).
- Tak, Rajkumar,Kumar, Manish,Menapara, Tusharkumar,Gupta, Naveen,Kureshy, Rukhsana I.,Khan, Noor-ul H.,Suresh
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supporting information
p. 3990 - 4001
(2017/11/22)
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- Asymmetric Transfer Hydrogenation of 1,3-Alkoxy/Aryloxy Propanones Using Tethered Arene/Ru(II)/TsDPEN Complexes
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A series of propanones containing combinations of aryloxy and alkoxy substituents at the 1- and 3-positions were reduced to the alcohols via asymmetric transfer hydrogenation using a tethered Ru(II)/TsDPEN catalyst. The enantioselectivities of the reductions reveal a complex pattern of electronic and steric effects which, when used in a matched combination, can lead to the formation of products of up to 68% ee (84:16 er) from this highly challenging class of substrate.
- Forshaw, Sam,Matthews, Alexander J.,Brown, Thomas J.,Diorazio, Louis J.,Williams, Luke,Wills, Martin
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supporting information
p. 2789 - 2792
(2017/06/07)
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- Site-Selective, Copper-Mediated O-Arylation of Carbohydrate Derivatives
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Site-selective functionalization of hydroxy groups in sugar derivatives is a major challenge in carbohydrate synthesis. Methods for achieving this goal will provide efficient access to new sugar-derived chemical building blocks and will facilitate the preparation or late-stage modification of complex oligosaccharides for applications in glycobiology research and drug discovery. Here, we describe site-selective, copper-promoted couplings of boronic acids with carbohydrate derivatives. These reactions generate sugar-derived aryl ethers, a structural class that is challenging to generate by other means and has not previously been accessed in a site-selective fashion. Experimental evidence and computational modeling suggest that the formation of a sugar-derived boronic ester intermediate is crucial to the selectivity of these processes, accelerating the arylation of an adjacent hydroxy group. The results demonstrate how the interactions of sugars with boron compounds can be combined with transition metal catalysis to achieve new chemical reactivity.
- Dimakos, Victoria,Garrett, Graham E.,Taylor, Mark S.
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supporting information
p. 15515 - 15521
(2017/11/06)
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- A novel convergent synthesis of the potent antiglaucoma agent tafluprost
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Tafluprost (AFP-168, 5) is a unique 15-deoxy-15,15-difluoro-16-phenoxy prostaglandin F2α (PGF2α) analog used as an efficacious ocular hypotensive agent in the treatment of glaucoma and ocular hypertension, as monotherapy, or as adjunctive therapy to β-blockers. A novel convergent synthesis of 5 was developed employing Julia-Lythgoe olefination of the structurally advanced prostaglandin phenylsulfone 16, also successfully applied for manufacturing of pharmaceutical grade latanoprost (2), travoprost (3) and bimatoprost (4), with an aldehyde !-chain synthon 17. The use of the same prostaglandin phenylsulfone 16, as a starting material in parallel syntheses of all commercially available antiglaucoma PGF2α analogs 2-5, significantly reduces manufacturing costs resulting from its synthesis on an industrial scale and development of technological documentation. Another key aspect of the route developed is deoxydifluorination of a trans-13,14-en-15-one 30 with Deoxo-Fluor. Subsequent hydrolysis of protecting groups and final esterification of acid 6 yielded tafluprost (5). The main advantages are the preparation of high purity tafluprost (5) and the application of comparatively cheap reagents. The preparation and identification of two other tafluprost acid derivatives, tafluprost methyl ester (32) and tafluprost ethyl amide (33), are also described.
- Krupa, Ma?gorzata,Chodyński, Micha?,Ostaszewska, Anna,Cmoch, Piotr,Dams, Iwona
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- Synthesis of 3-alkoxypropan-1,2-diols from glycidol: Experimental and theoretical studies for the optimization of the synthesis of glycerol derived solvents
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A straightforward synthetic methodology has been derived for the synthesis of glycerol monoethers from glycidol and alcohols. Several homogeneous and heterogeneous basic catalysts have been tested, the best results being obtained with readily available and inexpensive alkaline metal hydroxides. In the best case, good yield of the desired monoether is obtained under smooth reaction conditions, always with total conversion of glycidol. The selectivity of the reactions mainly depends on the alcohol used, due to the concurrence of undesired side reactions. A mechanistic study carried out through computational DFT calculations, in which solvent effects are taken into account, also complemented the experiments, has allowed to identify the main reaction paths taking place under reaction conditions, giving insights into the main causes affecting the reaction selectivity and also into how it could be improved.
- Leal-Duaso,Caballero,Urriolabeitia,Mayoral,García,Pires
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p. 4176 - 4185
(2017/09/07)
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- Glycerol as a source of designer solvents: Physicochemical properties of low melting mixtures containing glycerol ethers and ammonium salts
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In this work we report the preparation of mixtures of several alkyl glyceryl ethers, as hydrogen bond donor compounds, with two ammonium salts, choline chloride and N,N,N-triethyl-2,3-dihydroxypropan-1-aminium chloride. The stability of the mixtures at different molar ratios and temperatures has been evaluated in order to determine the formation of low melting mixtures. Liquid and stable mixtures have been characterized and their physico-chemical properties such as density, viscosity, refractive index, conductivity and surface tension have been measured in the temperature range of 293.15 K to 343.15 K. Comparison of the mixtures prepared herein with the ones containing glycerol and choline chloride evidences the possibility of tuning the physico-chemical properties by changing the substitution pattern in the hydrogen bond donor compound or in the ammonium salt, thus broadening the scope of application of these mixtures.
- Leal-Duaso, Alejandro,Pérez, Pascual,Mayoral, José A.,Pires, Elisabet,García, José I.
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p. 28302 - 28312
(2017/11/06)
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- Multivariate Metal-Organic Frameworks as Multifunctional Heterogeneous Asymmetric Catalysts for Sequential Reactions
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The search for versatile heterogeneous catalysts with multiple active sites for broad asymmetric transformations has long been of great interest, but it remains a formidable synthetic challenge. Here we demonstrate that multivariate metal-organic frameworks (MTV-MOFs) can be used as an excellent platform to engineer heterogeneous catalysts featuring multiple and cooperative active sites. An isostructural series of 2-fold interpenetrated MTV-MOFs that contain up to three different chiral metallosalen catalysts was constructed and used as efficient and recyclable heterogeneous catalysts for a variety of asymmetric sequential alkene epoxidation/epoxide ring-opening reactions. Interpenetration of the frameworks brings metallosalen units adjacent to each other, allowing cooperative activation, which results in improved efficiency and enantioselectivity over the sum of the individual parts. The fact that manipulation of molecular catalysts in MTV-MOFs can control the activities and selectivities would facilitate the design of novel multifunctional materials for enantioselective processes.
- Xia, Qingchun,Li, Zijian,Tan, Chunxia,Liu, Yan,Gong, Wei,Cui, Yong
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supporting information
p. 8259 - 8266
(2017/06/28)
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- Asymmetric hydrolysis of styrene oxide by PvEH2, a novel Phaseolus vulgaris epoxide hydrolase with extremely high enantioselectivity and regioselectivity
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A novel EH from Phaseolus vulgaris, PvEH2, was discovered based on the computer-aided analysis, and its encoding gene was cloned and expressed in E. coli Rossetta (DE3). The substrate spectrum of recombinant (re) PvEH2 was assayed, among which the enantiomeric ratio of rePvEH2 towards racemic styrene oxide (rac-1a) was > 200, while its regioselectivity coefficients, αS and βR, towards (S)- and (R)-1a were 99.1 and 69.8%, respectively. The asymmetric hydrolysis of 20 mM rac-1a by rePvEH2-expressing whole cells was performed at 25 °C, retaining (R)-1a with > 99.5% ees and 49.4% yield and producing (R)-phenyl-1,2-ethanediol (1b) with 96.2% eep and 49.7% yield in 40 min.
- Li, Chuang,Hu, Die,Zong, Xun-Cheng,Deng, Chao,Feng, Lei,Wu, Min-Chen,Li, Jian-Fang
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- Stereoselective Hydrolysis of Epoxides by reVrEH3, a Novel Vigna radiata Epoxide Hydrolase with High Enantioselectivity or High and Complementary Regioselectivity
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To provide more options for the stereoselective hydrolysis of epoxides, an epoxide hydrolase (VrEH3) gene from Vigna radiata was cloned and expressed in Escherichia coli. Recombinant VrEH3 displayed the maximum activity at pH 7.0 and 45 °C and high stability at pH 4.5-7.5 and 55 °C. Notably, reVrEH3 exhibited high and complementary regioselectivity toward styrene oxides 1a-3a and high enantioselectivity (E = 48.7) toward o-cresyl glycidyl ether 9a. To elucidate these interesting phenomena, the interactions of the three-dimensional structure between VrEH3 and enantiomers of 1a and 9a were analyzed by molecular docking simulation. Using E. coli/vreh3 whole cells, gram-scale preparations of (R)-1b and (R)-9a were performed by enantioconvergent hydrolysis of 100 mM rac-1a and kinetic resolution of 200 mM rac-9a in the buffer-free water system at 25 °C. These afforded (R)-1b with >99% eep and 78.7% overall yield after recrystallization and (R)-9a with >99% ees, 38.7% overall yield, and 12.7 g/L/h space-time yield.
- Hu, Die,Tang, Cunduo,Li, Chuang,Kan, Tingting,Shi, Xiaoling,Feng, Lei,Wu, Minchen
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p. 9861 - 9870
(2017/11/22)
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- Chemo- and Regioselective Functionalization of Polyols through Catalytic C(sp3)-C(sp3) Kumada-Type Coupling of Cyclic Sulfate Esters
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This contribution describes a copper-catalyzed, C(sp3)-C(sp3) cross-coupling reaction of cyclic sulfate esters, a distinct class of electrophilic derivatives of polyols, with alkyl Grignard reagents to afford functionalized alcohol products in good yields. The method is operationally simple and highlights the potential of cyclic sulfate esters as highly reactive substrates in catalytic, chemoselective polyol transformations.
- Ramírez-Contreras, Rodrigo,Morandi, Bill
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supporting information
p. 3718 - 3721
(2016/08/16)
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- Synthesis of enantiopure epoxide by 'one pot' chemoenzymatic approach using a highly enantioselective dehydrogenase
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Enantiopure α-phenethyl alcohols, including aromatic halohydrins, are important chiral building blocks. One of the best approaches to synthesise α-phenethyl alcohols is asymmetric reduction of prochiral ketones by alcohol dehydrogenases (ADHs). The obtained enantiopure halohydrin could be directly used to produce enantiopure epoxide through a base-induced ring-closure reaction, which is an attractive 'one pot' chemoenzymatic method for producing high-yield epoxide. In this study, a novel medium-chain dehydrogenase (KcDH) from Kuraishia capsulate CBS1993 was identified and characterised to show its broad substrate scope and excellent enantioselectivity. KcDH showed activities on 25 substrates of the 26 tested aromatic ketones and heteroaryl ketones, with an enantiomeric excess (ee) >99% and the highest relative activity observed with para-nitro acetophenone. Due to its high enantioselectivity for α-haloketones, a chemoenzymatic method for the synthesis of enantiopure styrene oxide (SO) and phenyl glycidyl ether (PGE) was developed through a base-induced ring-closure reaction on enantiopure halohydrin obtained with KcDH. (R)-SO and (S)-PGE were obtained in 86% and 94% analytical yield, respectively, and both epoxides were obtained with ee >99%. Thus, our results suggested that KcDH may be a promising biocatalyst for the production of multiple enantiopure α-phenethyl alcohols and epoxides.
- Wu, Kai,Chen, Lifeng,Fan, Haiyang,Zhao, Zhiqiang,Wang, Hualei,Wei, Dongzhi
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p. 899 - 904
(2016/02/05)
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- Transesterification Reactions Catalyzed by a Recyclable Heterogeneous Zinc/Imidazole Catalyst
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We report the development of a universal and recyclable heterogeneous zinc/imidazole catalyst. The catalyst is recoverable through simple filtration and can be reused at least five times, retaining its catalytic activity. Leached zinc species were not responsible for the observed catalysis based on the hot filtration test and ICP-MS analysis. The heterogeneous zinc catalyst also promotes chemoselective transesterification over amidation. (Figure presented.).
- Nakatake, Daiki,Yazaki, Ryo,Matsushima, Yoshimasa,Ohshima, Takashi
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supporting information
p. 2569 - 2574
(2016/08/16)
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- INHIBITORS OF BRUTON'S TYROSINE KINASE
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Disclosed herein are compounds that inhibit Bruton's tyrosine kinase (Btk). Also described are irreversible inhibitors of Btk. In addition, reversible inhibitors of Btk are also described. Also disclosed are pharmaceutical compositions that include the compounds. Methods of using the Btk inhibitors are disclosed, alone or in combination with other therapeutic agents, for the treatment of autoimmune diseases or conditions, heteroimmune diseases or conditions, cancer, including lymphoma, and inflammatory diseases or conditions.
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Paragraph 00708
(2016/01/25)
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- A highly efficient protocol for regioselective ring-opening of epoxides with alcohols, water, acetic acid, and acetic anhydride catalyzed by SbF3
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SbF3as an efficient catalyst has been used for regioselective alcoholysis, acetolysis and hydrolysis of epoxides to the corresponding β-alkoxy, β-acetoxy alcohols, and 1,2-diols in high to excellent yields. This study also represents a convenient synthesis of vic-diacetates from ring-opening of epoxides with acetic anhydride.
- Zeynizadeh, Behzad,Gilanizadeh, Masumeh,Aminzadeh, Farkhondeh Mohammad
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p. 1051 - 1056
(2016/07/06)
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- Aniline-terephthalaldehyde resin p-toluenesulfonate (ATRT) as a highly efficient and reusable catalyst for alcoholysis, hydrolysis, and acetolysis of epoxides
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Alcoholysis, hydrolysis, and acetolysis of epoxides were carried out in the presence of a catalytic amount of aniline-terephthalaldehyde resin p-toluenesulfonate (ATRT) to give the corresponding β-substituted alcohols in good yields. Alcoholysis and hydrolysis of epoxides catalyzed by ATRT proceeded faster than those by pyridinium p-toluenesulfonate (PPTS).
- Tanemura, Kiyoshi,Suzuki, Tsuneo
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supporting information
p. 1781 - 1789
(2016/11/17)
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- Polymer enzyme conjugates as chiral ligands for sharpless dihydroxylation of alkenes in organic solvents
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Conjugates of enzymes and poly(2-methyloxazoline) were used as organosoluble amphiphilic polymer nanocontainers for dissolving osmate, thereby converting the enzymes into organosoluble artificial metalloenzymes. These were shown to catalyze the dihydroxylation of different alkenes with high enantio-selectivity The highest selectivities, found for osmate complexed with laccase polymer-enzyme conjugates (PECs), even exceed those of classical Sharpless catalysts.
- Konieczny, Stefan,Leurs, Melanie,Tiller, Joerg C.
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- First example of borirane synthesis by α-olefins reaction with BCl3·SMe2 Catalyzed with (η5-C5H5)2TiCl2
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New method was developed of the synthesis of 2-phenyl(alkyl, benzyl, phenoxy)-1-chloroboriranes via reaction of α-olefins with BCl3·SMe2 catalyzed by Cp2TiCl2. The method is based on the boracyclopropanes (boriranes) formation resulting from transmetallation of titanacyclopropanes arising from the reaction of α-olefins with Cp2TiCl2. The calculations were fulfilled of thermodynamic and activation parameters of possible reaction routes.
- Khusainova,Khafizova,Tyumkina,Dzhemilev
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p. 1517 - 1523
(2015/12/30)
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- Ring opening of epoxides by using cross-linked poly(4-vinylpyridine)-supported thiocyanate in the presence of polymer-supported sulfuric acid under solvent-free conditions
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Cross-linked poly(4-vinylpyridine)-supported thiocyanate ion, [P4-VP]SCN, is introduced as recyclable polymeric reagent for the efficient and regioselective conversion of epoxides to thiocyanohydrins in the presence of cross-linked poly(4-vinylpyridine)-supported sulfuric acid, [P4-VP]H2SO4, as a solid proton source and as catalyst under solvent-free conditions. The ring-opening reaction of epoxides take place very fast under solvent-free conditions and the regioselective thiocyanohydrins are prepared in high yields at 65°C. The present method offers advantages such as short reaction time, simple reaction work-up, and the polymeric reagents can be regenerated and reused several times without significant loss of their activity.
- Ali, Mohammad,Zarchi, Karimi,Tarabsaz, Ali
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p. 550 - 560
(2015/05/20)
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- A PROPYL-PHENYL-ETHER DERIVATIVE, AND MELANOGENESIS INHIBITOR, SKIN-LIGHTENING AGENT, ANTIMICROBIAL AGENT AND COSMETIC CONTAINING SAID PROPYL-PHENYL-ETHER DERIVATIVE
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Provided is a compound that exhibits an excellent melanogenesis-inhibiting effect (skin-lightening effect), exhibits an excellent antimicrobial effect, excels in terms of temporal stability and the like, and is suitable for use as an ingredient of a cosmetic. Said compound is a propyl-phenyl-ether derivative compound comprising a propyl group that has a substituent such as a hydroxyl group and is bound to the hydroxyl group of a phenol group that has a substituent such as a tert-butyl group. A melanogenesis inhibitor, skin-lightening agent, and antimicrobial agent containing the aforementioned compound as an active ingredient are also provided, as is a cosmetic characterized by containing said compound.
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Paragraph 0155-0157
(2016/12/12)
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- Osmium on chelate resin: Nonvolatile catalyst for the synthesis of DIOLS from alkenes
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Osmium tetraoxide (OsO4) was immobilized on a commercially available chelate resin DIAION CR11 (CR11) just by simply immersing it in a methanol solution of OsO4 at room temperature. The resulting purple solid, 5% Os/CR11, indicated no volatility, and effectively catalyzed the oxidation of various alkenes to the corresponding diols.
- Monguchi, Yasunari,Wakayama, Fumika,Takada, Hitoshi,Sawama, Yoshinari,Sajiki, Hironao
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supporting information
p. 700 - 704
(2015/03/14)
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- Three different types of chirality-driven crystallization within the series of uniformly substituted phenyl glycerol ethers
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Seven chiral arylglycerol ethers 2-R-C6H4-O-CH2CH(OH)CH2OH (R 5 H, Me, Et, Allyl, n-Pr, i-Pr, tert-Bu) were synthesized in racemic and scalemic form. The IR spectra, melting points, and enthalpies of fusion for racemic and scalemic samples of every species were measured, the entropies of enantiomers mixing in the liquid state and Gibbs free energies of a racemic compound formation were derived and binary phase diagrams were reconstructed for the whole family. Solid racemic compounds stabilities were ranked for the four substances. Spontaneous resolution was established for the registered chiral drug mephenesin and its ethyl analogue. Metastable anomalous conglomerate, forming crystals having three independent R and one independent S molecules in the unit cell, is formed during solution crystallization of tert-butyl derivative; metastable phase transforms slowly into traditional racemic conglomerate. Chirality 20:1092-1103, 2008.
- Bredikhin, Alexander A.,Bredikhina, Zemfira A.,Novikova, Victorina G.,Pashagin, Alexander V.,Zakharychev, Dmitry V.,Gubaidullin, Aidar T.
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p. 1092 - 1103
(2015/02/05)
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- A novel chemoselective cleavage of (tert-butyl)(dimethyl)silyl (TBS) ethers catalyzed by Ce(SO4)2·4 H2O
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(tert-Butyl)(dimethyl)silyl (tBuMe2Si; TBS) phenyl/alkyl ethers were efficiently cleaved to the corresponding parent hydroxy compounds in good yields using catalytic amounts of Ce(SO4) 2·4 H2O by microwave-assisted or conventional heating in MeOH. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl (iPr3Si; TIPS) and (tert-butyl)(diphenyl)silyl ( tBuPh2Si; TBDPS) ethers. Copyright
- González-Calderón, Davir,González-González, Carlos A.,Fuentes-Benítez, Aydeé,Cuevas-Yá?ez, Erick,Corona-Becerril, David,González-Romero, Carlos
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p. 965 - 972
(2014/08/05)
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- Aluminium chloride hexahydrate (AlCl3.6H2o): An efficient, facile, mild, and highly chemoselective catalytic deprotection of tert-butyldimethylsilyl (tbs) ethers
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tert-Butyldimethylsilyl (TBS) phenyl / alkyl ethers were cleaved to the corresponding efficiently parent hydroxyl compounds in good yields using catalytic amounts of AlCl3.6H2O by conventional or microwave-assisted heating in methanol or isopropanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of TBS ethers in the presence of triisopropylsilyl and tert-butyldiphenylsilyl ethers.
- Gonzalez-Calderon, Davir,Benitez-Puebla, Luis J.,Gonzalez-Gonzalez, Carlos A.,Garcia-Eleno, Marco A.,Fuentes-Benitez, Aydee,Cuevas-Yanez, Erick,Corona-Becerril, David,Gonzalez-Romero, Carlos
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p. 1258 - 1265
(2014/04/17)
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- DEPROTECTION METHOD FOR PROTECTED HYDROXYL GROUP
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To deprotect an alcoholic hydroxyl group protected by a t-butyldimethylsilyl group without influencing a functional group unstable to an acid. In the presence of a solvent, an alcohol having a hydroxyl group protected by a t-butyldimethylsilyl group is deprotected in the presence of an acid or an acid salt having a pKa of from 1.0 to 3.0 in water.
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Paragraph 0070-0072
(2014/03/24)
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- 1,3-Dimethylimidazolium-2-carboxylate: A zwitterionic salt for the efficient synthesis of vicinal diols from cyclic carbonates
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The development of efficient, cheap and recyclable catalysts for reactions under mild reaction conditions is a very attractive topic in green chemistry. Herein, a series of basic ionic liquids (ILs) were investigated as catalysts for the synthesis of vicinal diols via the hydrolysis of cyclic carbonates in order to improve this kind of synthetic process. The effects of the IL structure, the molar ratio of cyclic carbonate to water, and various reaction parameters on the catalytic performance were investigated in detail. It was found that 1,3-dimethylimidazolium-2-carboxylate, a simple halogen-free zwitterionic catalyst, showed high activity (a space-time yield of 1086 h-1) and excellent selectivity for the preparation of ethylene glycol via the hydrolysis of ethylene carbonate. The catalyst could be reused over six times without obvious loss of catalytic activity. Also, it was applicable to a variety of cyclic carbonates for the production of their corresponding vicinal diols with high yields and selectivities. A possible catalytic cycle for this kind of catalytic process was proposed based on the experimental results, NMR spectroscopy and theoretical calculations. This reaction protocol opens a new possibility for chemical synthesis as a substitution for traditional base or basic ILs. This journal is the Partner Organisations 2014.
- Sun, Jian,Yao, Xiaoqian,Cheng, Weiguo,Zhang, Suojiang
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p. 3297 - 3304
(2014/06/10)
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- Osmium impregnated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenes
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A new catalyst derived from osmium has been prepared, fully characterized and tested in the dihydroxylation of alkenes. The catalyst was prepared by wet impregnation methodology of OsCl3·3H2O on a commercial micro-magnetite surface. The catalyst allowed the reaction with one of the lowest osmium loadings for a heterogeneous catalyst and was selective for the monodihydroxylation of 1,5-dienes. Moreover, the catalyst was easily removed from the reaction medium by the simple use of a magnet. The selectivity of catalyst is very high with conversions up to 99%. Preliminary kinetics studies showed a first-order reaction rate with respect to the catalyst.
- Cano, Rafael,Pérez, Juana M.,Ramón, Diego J.
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p. 177 - 182
(2014/01/06)
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- Bifunctional aluminum catalyst for CO2 fixation: Regioselective ring opening of three-membered heterocyclic compounds
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Regioselective ring opening of three-membered heterocyclic compounds (epoxides or N-substituted aziridines) at various temperatures was observed in coupling reactions with CO2 by the use of an aluminum - salen catalyst in conjunction with intramolecular quaternary ammonium salts as cocatalysts, affording the corresponding five-membered cyclic products with complete configuration retention at the methine carbon. Notably, this bifunctional aluminum-based catalyst exhibited nearly 100% regioselectivity for the ring opening at the methylene C-O bond for various terminal epoxides. This was true for those bearing an electron-withdrawing group, such as styrene oxide or epichlorohydrin, thereby affording the synthesis of various enantiopure cyclic carbonates that have previously been obtained only rarely by other methods. An intramolecular cooperative catalysis is suggested to contribute to the high activity and excellent stereochemistry control observed. Surprisingly, the highly selective ring opening at the methine carbon of N-substituted aziridines was found in the coupling with CO2, predominantly giving 5-substituted oxazolininones with retention of configuration as a result of double inversion at the methine carbon. (Chemical Equation Presented).
- Ren, Wei-Min,Liu, Ye,Lu, Xiao-Bing
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supporting information
p. 9771 - 9777
(2015/02/19)
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- Heterobimetallic dual-catalyst systems for the hydrolytic kinetic resolution of terminal epoxides
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A heterobimetallic dual-catalyst system based on the preparation and use of various salen complexes has been developed for the hydrolytic kinetic resolution (HKR) of terminal epoxides. A combination of cobalt-salen and manganese-salen complexes, generated from ligands with the same configuration possessing thiophene or pyrrole moieties, produced indeed highly selective catalysts for the hydrolysis of epibromohydrin. This effect could also be extended to other terminal epoxides and to the more challenging ring opening of cyclohexene oxide. Kinetic studies indicated that only one CoIII salen complex was involved in the rate-determining step, which supported a heterobimetallic highly enantioselective pathway based on the crucial existence of in situ generated CoIII-OH species, previously postulated in the literature. The beneficial effect of the presence of additional Mn-complexes was ascribed to the inhibition of the alternative less enantioselective monometallic reaction pathway by epoxide activation.
- Hong, Xiang,Mellah, Mohamed,Schulz, Emmanuelle
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p. 2608 - 2617
(2014/07/22)
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- One-pot synthesis of aryloxypropanediols from glycerol: Towards valuable chemicals from renewable sources
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Glycerol offers an easy and green route for the synthesis of aryloxypropanediols of known pharmacological activity. Glycerol is selectively converted to aryloxypropanediols in a one-pot reaction, through in situ formed glycerol carbonate, under benign and solvent-free conditions. Catalyst and unreacted reagent can be recycled.
- Truscello, Ada M.,Gambarotti, Cristian,Lauria, Mirvana,Auricchio, Sergio,Leonardi, Gabriella,Shisodia, Suresh U.,Citterio, Attilio
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p. 625 - 628
(2013/03/29)
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- Zn(ii), Cd(ii) and Cu(ii) complexes of 2,5-bis{N-(2,6-diisopropylphenyl) iminomethyl}pyrrole: Synthesis, structures and their high catalytic activity for efficient cyclic carbonate synthesis.
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The syntheses of Zn(ii), Cd(ii) and Cu(ii) complexes of 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrole (DIP2pyr)H 1 and their catalytic activities in CO2 fixation are reported. The structures of these complexes were characterized by IR, 1H, 13C NMR and single crystal X-ray diffraction techniques. The catalytic activities of these complexes for the cycloaddition of CO2 to an epoxide under one atmosphere of pressure and mild temperature conditions to yield cyclic carbonate have been studied. Among the four complexes synthesized, the Zn(ii) and Cu(ii) complexes were found to be versatile whereas the Cu(ii) complex was more selective in the conversion. They were highly effective for the conversion of monosubstituted terminal epoxides, disubstituted terminal and internal epoxides to their corresponding cyclic carbonates with good to high yields. The Royal Society of Chemistry 2013.
- Vignesh Babu, Heeralal,Muralidharan, Krishnamurthi
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supporting information
p. 1238 - 1248
(2013/02/23)
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- Asymmetric diboration of terminal alkenes with a rhodium catalyst and subsequent oxidation: Enantioselective synthesis of optically active 1,2-diols
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Pin it down: A highly enantioselective diboration of terminal alkenes with chiral 1 and bis(pinacolato)diboron (B2pin2) was realized. Subsequent oxidation of the diboron adducts with sodium peroxoborate readily gave the corresponding optically active 1,2-diols in high yields and high enantioselectivities. Copyright
- Toribatake, Kenji,Nishiyama, Hisao
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supporting information
p. 11011 - 11015
(2013/10/22)
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- Cerium(IV) sulfate tetrahydrate: A catalytic and highly chemoselective deprotection of THP, MOM, and BOM ethers
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Tetrahydropyranyl (THP), methoxymethyl (MOM), and benzyloxymethyl (BOM) phenyl/alkyl ethers were efficiently cleaved to the corresponding parent hydroxyl compounds in good yields using catalytic amounts of Ce(SO 4)2·4H2O by microwave-assisted or conventional heating in methanol solution. Intramolecular and competitive experiments demonstrated the chemoselective deprotection of THP ethers in the presence of triisopropylsilyl (TIPS) and tert-butyldiphenylsilyl (TBDPS) phenyl ethers.
- González-Calderón, Davir,González-González, Carlos A.,Fuentes-Benítez, Aydeé,Cuevas-Yá?ez, Erick,Corona-Becerril, David,González-Romero, Carlos
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p. 7164 - 7166
(2013/12/04)
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- Heterogeneous palladium-catalyzed synthesis of aromatic ethers by solvent-free dehydrogenative aromatization: Mechanism, scope, and limitations under aerobic and non-aerobic conditions
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Starting from cyclohexanone derivatives and alcohols, both non-aromatic precursors, aryl ethers could be synthesized in good yields and with good selectivities in the presence of a catalytic amount of Pd/C, in one step, without added solvent, in a reaction vessel open to air. For less reactive substrates, the addition of 1-octene in a closed system under non-aerobic conditions improved the conversion. In addition, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. The process was also used with tetralone derivatives and polyols. Several reactions were performed to propose a mechanism for this transformation. The formation of an enol ether followed by a dehydrogenation reaction seem to be the key steps of this reaction. Aryl ethers were prepared in good yields and with good selectivities in a solvent-free and heterogeneous catalytic dehydrogenative alkylation of cyclohexanones with various alcohols. Three different complementary routes were used, and for the first time, non-aerobic, safe conditions could be used. Moreover, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. Copyright
- Sutter, Marc,Lafon, Romain,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 5902 - 5916
(2013/09/23)
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- Straightforward heterogeneous palladium catalyzed synthesis of aryl ethers and aryl amines via a solvent free aerobic and non-aerobic dehydrogenative arylation
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Aryl ethers have been prepared from cyclohexanone derivatives and various alcohols in the presence of a catalytic amount of palladium on charcoal. The formation of an enol ether followed by an aerobic or non-aerobic dehydrogenation reaction, seem to be the key steps of this transformation. In addition, this new method was also adapted for the synthesis of arylamines.
- Sutter, Marc,Sotto, Nicolas,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 347 - 352
(2013/03/28)
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- 1,2,3-Trimethoxypropane and glycerol ethers as bio-sourced solvents from glycerol: Synthesis by solvent-free phase-transfer catalysis and utilization as an alternative solvent in chemical transformations
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1,2,3-Trimethoxypropane (2), 1-alkoxy-2,3-dimethoxy-propanes, and 1-aryloxy-2,3-dimethoxypropanes were prepared in good yields and selectivity by solid-liquid phase-transfer catalysis in the presence of an inorganic base and an ammonium salt as the phase-transfer catalyst with no additional solvent. No heating was required, and the synthesis was easily performed under atmospheric pressure on a 150g scale. For the preparation of 2, the conversion of glycerol was complete and the selectivity for the expected glycerol trimethylether was above 95%. This product was utilized as a solvent in organic reactions such as transesterifications between glycerol and vegetable oil, organometallic reactions (Grignard- and Barbier-type reactions), carbon-carbon coupling reactions (Suzuki, Sonogashira, Heck), and in etherification reactions by dehydrogenative alkylation. The solvent showed interesting properties for the solubilization of polymers.
- Sutter, Marc,Dayoub, Wissam,Metay, Estelle,Raoul, Yann,Lemaire, Marc
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p. 2893 - 2904
(2013/10/21)
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- Molecular characterization of NbEH1 and NbEH2, two epoxide hydrolases from Nicotiana benthamiana
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Plant epoxide hydrolases (EH) form two major clades, named EH1 and EH2. To gain a better understanding of the biochemical roles of the two classes, NbEH1.1 and NbEH2.1 were isolated from Nicotiana benthamiana and StEH from potato and heterologously expressed in Escherichia coli. The purified recombinant proteins were assayed with a variety of substrates. NbEH1.1 only accepted some aromatic epoxides, and displayed the highest enzyme activity towards phenyl glycidyl ether. In contrast, NbEH2.1 displayed a broad substrate range and similar substrate specificity as StEH. The latter enzymes showed activity towards all fatty acid epoxides examined. The activity (Vmax) of NbEH1.1 towards phenyl glycidyl ether was 10 times higher than that of NbEH2.1. On the contrary, NbEH2.1 converted cis-9,10-epoxystearic acid with Vmax of 3.83 μmol min mg-1 but NbEH1.1 could not hydrolyze cis-9,10- epoxystearic acid. Expression analysis revealed that NbEH1.1 is induced by infection with tobacco mosaic virus (TMV) and wounding, whereas NbEH2.1 is present at a relatively constant level, not influenced by treatment with TMV and wounding. NbEH1.1 transcripts were present predominantly in roots, whereas NbEH2.1 mRNAs were detected primarily in leaves and stems. Overall, these two types of tobacco EH enzymes are distinguished not only by their gene expression, but also by different substrate specificities. EH1 seems not to participate in cutin biosynthesis and it may play a role in generating signals for activation of certain defence and stress responses in tobacco. However, members of the EH2 group hydrate fatty acid epoxides and may be involved in cutin monomer production in plants.
- Huang, Fong-Chin,Schwab, Wilfried
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- Catalysis through temporary intramolecularity: Mechanistic investigations on aldehyde-catalyzed cope-type hydroamination lead to the discovery of a more efficient tethering catalyst
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Mechanistic investigations on the aldehyde-catalyzed intermolecular hydroamination of allylic amines using N-alkylhydroxylamines are presented. Under the reaction conditions, the presence of a specific aldehyde catalyst allows formation of a mixed aminal intermediate, which permits intramolecular Cope-type hydroamination. The reaction was determined to be first-order in both the aldehyde catalyst (α-benzyloxyacetaldehyde) and the allylic amine. However, the reaction displays an inverse order behavior in benzylhydroxylamine, which reveals a significant off-cycle pathway and highlights the importance of an aldehyde catalyst that promotes a reversible aminal formation. Kinetic isotope effect experiments suggest that hydroamination is the rate-limiting step of this catalytic cycle. Overall, these results enabled the elaboration of a more accurate catalytic cycle and led to the development of a more efficient catalytic system for alkene hydroamination. The use of 5-10 mol % of paraformaldehyde proved more effective than the use of 20 mol % of α-benzyloxyacetaldehyde, leading to high yields of intermolecular hydroamination products within 24 h at 30 °C.
- Guimond, Nicolas,MacDonald, Melissa J.,Lemieux, Valerie,Beauchemin, Andre M.
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supporting information
p. 16571 - 16577,7
(2020/09/15)
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- Asymmetric organocatalytic efficiency of synthesized chiral β-amino alcohols in ring-opening of glycidol with phenols
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A series of novel chiral β-amino alcohols 3-5 and 7-10 were synthesized by regioselective ring opening of epoxides and chiral amines with a straightforward method in high yields (up to 99 %). Kinetic resolution of racemic glycidol with phenols was achieved by using chiral amino alcohols as organocatalysts. Amino alcohols 5, 8 and 10 exhibited the highest enantioselectivities with p-cresol, phenol, and p-methoxyphenol by 63, 65, 58 % ee, respectively. The moderate enantioselectivities were observed with catalyst 9b towards all the nucleophiles (34-48 % ee). The ee values of the desired 3-aryloxy-1, 2-diols were determined by HPLC. This study presents an attractive tool for the synthesis of β-blockers and structurally complex molecules.
- Aral, Tarik,Karakaplan, Mehmet,Hosgoeren, Halil
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experimental part
p. 794 - 802
(2012/08/28)
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