- Catalytic asymmetric cyano-phosphorylation of aldehydes using a YLi3tris(binaphthoxide) complex (YLB)
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A highly enantioselective cyano-phosphorylation of aldehydes catalyzed by a YLi3tris(binaphthoxide) complex YLB 1 is described. The slow addition of diethyl cyanophosphonate 4 to aldehydes 5 in the presence of YLB 1 (10 mol %), H2O (30 mol %), tris(2,6-dimethoxyphenyl)phosphine oxide 3a (10 mol %), and BuLi (10 mol %) afforded cyanohydrin O-phosphates 6 in up to 98% yield and 97% ee. Mechanistic studies revealed that the addition of cyanide to aldehydes is irreversible and determines the enantioselectivity. The reaction mechanism is also discussed in detail.
- Yamagiwa, Noriyuki,Abiko, Yumi,Sugita, Mari,Tian, Jun,Matsunaga, Shigeki,Shibasaki, Masakatsu
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Read Online
- Determination of the time course of an enzymatic reaction by 1H NMR spectroscopy: Hydroxynitrile lyase catalysed transhydrocyanation
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The time course of the enzyme catalysed transhydrocyanation of benzaldehyde to give (S)-mandelonitrile was investigated using a hydroxynitrile lyase from Hevea brasiliensis as catalyst and acetone cyanohydrin as cyanide donor. Employing special techniques it was possible to apply 1H NMR spectroscopy in aqueous medium to monitor the concentration changes of all substrates and products. By this technique strong evidence for inhibition of the enzyme at higher substrate concentrations was obtained.
- Hickel,Gradnig,Griengl,Schall,Sterk
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Read Online
- High-yield DL-mandelic acid synthesis process
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The invention provides a high-yield DL-mandelic acid synthesis process. The synthesis process specifically comprises the following steps: 1, treating benzaldehyde by using sodium hydrogen sulfite to obtain benzaldehyde sodium hydrogen sulfite; 2, extracting the benzaldehyde sodium hydrogen sulfite by using an organic solvent, recovering unreacted benzaldehyde in the benzaldehyde sodium hydrogen sulfite, and adding sodium cyanide after the extraction is completed to prepare mandelonitrile; 3, adding an inorganic acid, and then carrying out heating and pressure maintaining treatment to hydrolyze the mandelonitrile so as to obtain mandelic acid; and 4, purifying the mandelic acid. According to the method, the step of extracting the p-benzaldehyde sodium hydrogen sulfite salt is added, so that the probability that the product purity is reduced due to benzoin condensation is reduced, the recycled benzaldehyde can be returned to the raw material for use, and the yield can be increased in multiple rounds of reactions; and the hydrolysis process of the mandelonitrile adopts heating and pressure maintaining treatment, so that consumption of inorganic acid can be reduced, and the hydrolysis efficiency is improved.
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- Constructing a triangular metallacycle with salen-Al and its application to a catalytic cyanosilylation reaction
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A triangular metallosalen-based metallacycle was constructed in quantitative yield by the self-assembly of a 180° bis(pyridyl)salen-Al complex and a 60° diplatinum(ii) acceptor in a 1?:?1 stoichiometric ratio. This metallacycle was then successfully used to cyanosilylate a wide range of benzaldehydes with trimethylsilyl cyanide.
- Li, Bo,Li, Yang,Qiu, Huayu,Xu, Jun,Yin, Shouchun,Zhang, Jinjin,Zhang, Pengfei,Zhang, Yueyue
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p. 10399 - 10402
(2021/10/12)
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- Application of an Electrochemical Microflow Reactor for Cyanosilylation: Machine Learning-Assisted Exploration of Suitable Reaction Conditions for Semi-Large-Scale Synthesis
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Cyanosilylation of carbonyl compounds provides protected cyanohydrins, which can be converted into many kinds of compounds such as amino alcohols, amides, esters, and carboxylic acids. In particular, the use of trimethylsilyl cyanide as the sole carbon source can avoid the need for more toxic inorganic cyanides. In this paper, we describe an electrochemically initiated cyanosilylation of carbonyl compounds and its application to a microflow reactor. Furthermore, to identify suitable reaction conditions, which reflect considerations beyond simply a high yield, we demonstrate machine learning-assisted optimization. Machine learning can be used to adjust the current and flow rate at the same time and identify the conditions needed to achieve the best productivity.
- Sato, Eisuke,Fujii, Mayu,Tanaka, Hiroki,Mitsudo, Koichi,Kondo, Masaru,Takizawa, Shinobu,Sasai, Hiroaki,Washio, Takeshi,Ishikawa, Kazunori,Suga, Seiji
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supporting information
p. 16035 - 16044
(2021/09/02)
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- Valmet Chiral Schiff-Base Ligands And Their Copper(II) Complexes as Organo, Homogeneous and Heterogeneous Catalysts for Henry, Cyanosilylation and Aldol Coupling Reactions
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Cyanosilylation, aldol coupling and asymmetric Henry reactions were carried out with L- and D-valmet ligands in different configurations: i) coordinated to sodium ions, as organocatalysts, with week base properties, ii) complexes with copper(II), as homogeneous catalysts, and iii) immobilized copper(II) complexes onto graphene oxide (GO) as heterogeneous catalysts. For the reaction of benzaldehyde and nitromethane in water these afforded an asymmetric Henry reaction, with a spectacular increase of the conversion and ee (92.5 and 95.8 %, respectively) after the deposition on GO. Ligand complexed copper was also effective for cyanosilylation and Aldol coupling reaction.
- Arora, Zinnia,Eftemie, Diana-Ioana,Spinciu, Adela,Maxim, C?t?lin,Hanganu, Ana-Maria,Tudorache, Madalina,Cojocaru, Bogdan,Pavel, Octavian D.,Granger, Pascal,Andruh, Marius,Parvulescu, Vasile I.
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p. 4634 - 4644
(2021/09/08)
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- Synthesis of Acrylonitriles via Mild Base Promoted Tandem Nucleophilic Substitution-Isomerization of α-Cyanohydrin Methanesulfonates
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Main observation and conclusion: We have developed an efficient synthesis of acrylonitriles via mild base promoted tandem nucleophilic substitution-isomerization of α-cyanohydrin methanesulfonates with alkenylboronic acids. This transition metal-free protocol works under simple and mild conditions and offers good chemical yields for a wide range of substrates and demonstrates good functional group tolerance. (Figure presented.).
- Liu, Shiwen,Meng, Lingling,Zeng, Xiaojun,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 913 - 917
(2021/04/05)
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- CO2-Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**
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Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2-mediated selective cyanohydrin synthesis was further showcased by broadening Kiliani–Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl- and arylaldehydes, KCN and an atmospheric pressure of CO2.
- Juhl, Martin,Petersen, Allan R.,Lee, Ji-Woong
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supporting information
p. 228 - 232
(2020/11/30)
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- Designing of amino functionalized imprinted polymeric resin for enantio-separation of (±)-mandelic acid racemate
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S-Mandelic acid (MA) enantio-selective resinous material functionalized with –NH2 groups has been developed and effectively utilized in chiral separation of (±)-MA racemate solution. S-MA has first combined with the polymerizable p-aminophenol and form the corresponding amide derivative, which was then polymerized with phenol/formalin using HCl as a catalyst. The stereo-selective –NH2 functionalized binding sites were then generated within the resin upon the alkaline degradation of the amide linkages followed by acidic treatments that will expel the resin incorporated S-MA out of the polymeric material to get the S-MA imprinted polymer (S-MAPR). The synthesized S-MA chiral amide derivative along with the developed polymeric resin was investigated by various techniques including FTIR and NMR spectra that confirmed the executed chemical modifications. In addition, the morphological appearance of the obtained resins were observed using SEM images. Moreover, the S-MAPR resin was examined to optimize the enantio-selective separation conditions and the studies indicated that the adsorption reached the highest value at pH 7 and the maximum capacity was 243 ± 1 mg/g. In addition, the chiral separation of (±)-MA racemic solution was successfully executed by the S-MAPR separation column with 55% and 82% enantiomeric excess of R- and S-MA within both the initial loading and recovery eluant solutions, respectively.
- Alhawiti, Aliyah S.,Monier,Elsayed, Nadia H.
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- CO2-Mediated Non-Destructive Cyanide Wastewater Treatment
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The facile removal of cyanide anions from cyanide-containing water was achieved using CO2 in conjunction with aldehydes which can be recycled from the process. The conversion of the cyanide ion into an insoluble cyanohydrin in water allowed the removal of cyanide and could be used as a method for treating cyanide contaminated wastewater and for recovering cyanide or cyanohydrins for further applications.
- Juhl, Martin,Lee, Ji-Woong,Petersen, Allan R.,Petrovic, Aleksa
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supporting information
p. 5003 - 5007
(2021/09/30)
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- Enantioselective Synthesis of α-Thiocarboxylic Acids by Nitrilase Biocatalysed Dynamic Kinetic Resolution of α-Thionitriles
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The enantioselective synthesis of α-thiocarboxylic acids by biocatalytic dynamic kinetic resolution (DKR) of nitrile precursors exploiting nitrilase enzymes is described. A panel of 35 nitrilase biocatalysts were screened and enzymes Nit27 and Nit34 were found to catalyse the DKR of racemic α-thionitriles under mild conditions, affording the corresponding carboxylic acids with high conversions and good-to-excellent ee. The ammonia produced in situ during the biocatalytic transformation favours the racemization of the nitrile enantiomers and, in turn, the DKR without the need of any external additive base.
- Lauder, Kate,Anselmi, Silvia,Finnigan, James D.,Qi, Yuyin,Charnock, Simon J.,Castagnolo, Daniele
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p. 10422 - 10426
(2020/07/24)
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- One-pot method for the synthesis of 1-aryl-2-aminoalkanol derivatives from the corresponding amides or nitriles
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We have identified a novel one-pot method for the synthesis of β-amino alcohols, which is based on C-H bond hydroxylation at the benzylic α-carbon atom with a subsequent nitrile or amide functional group reduction. This cascade process uses molecular oxygen as an oxidant and sodium bis(2-methoxyethoxy)aluminum hydride as a reductant. The substrate scope was examined on 30 entries and, although the respective products were provided in moderate yields only, the above simple protocol may serve as a direct and powerful entry to the sterically congested 1,2-amino alcohols that are difficult to prepare by other routes. The plausible mechanistic rationale for the observed results is given and the reaction was applied to a synthesis of a potentially bioactive target. This journal is
- Bobal, Pavel,Otevrel, Jan,Svestka, David
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p. 25029 - 25045
(2020/07/14)
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- Highly chemoselective and efficient Strecker reaction of aldehydes with TMSCN catalyzed by MgI2 etherate under solvent-free conditions
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Strecker reaction of various substituted aromatic aldehydes, heteroaromatic aldehydes, aliphatic aldehydes and α,β-unsaturated aldehydes with trimethylsilyl cyanide (TMSCN) was realized in the presence of 5 mol % of MgI2 etherate in a mild, efficient and highly chemoselective manner under solvent-free conditions.
- He, Kailun,Liu, Huijun,Zhang, Xingxian,Zhou, Jing
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supporting information
p. 933 - 936
(2019/03/08)
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- Postfunctionalized Metalloligand-Based Catenated Coordination Polymers: Syntheses, Structures, and Effect of Labile Sites on Catalysis
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In this work, pyridyl-appended Co3+ complexes (1 and 2) have been postfunctionalized by using 4-(bromomethyl)benzoic acid, thus changing the functionalities from pyridyl-N donors to carboxylate-O donors. Using two such postfunctionalized metalloligands (3 and 4), several homo and heterometallic coordination polymers (HCPs) have been synthesized. Single crystal structural analyses revealed that all HCPs presented intriguing one-dimensional catenated architectures. Postsynthetic modification induced flexibility was found to be responsible for the nearly identical architectures for two sets of HCPs starting from two different postfunctionalized metalloligands, 3 and 4. Two sets of HCPs differed by the presence (3a-3d) or absence (4a-4b) of labile coordinated water molecules that demonstrated a profound effect on the heterogeneous catalysis of Knoevenagel condensation reactions and cyanation reactions.
- Pandey, Saurabh,Kumar, Girijesh,Gupta, Rajeev
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p. 2723 - 2735
(2019/05/01)
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- Preparation of O-Protected Cyanohydrins by Aerobic Oxidation of α-Substituted Malononitriles in the Presence of Diarylphosphine Oxides
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A mild, reagent-cyanide-free, and efficient synthesis of O-phosphinoyl-protected cyanohydrins from readily available α-substituted malononitriles was realized using diarylphosphine oxides in the presence of O2. Mechanistic studies indicated that in addition to the initial aerobic oxidation of the malononitrile derivative notable features of this process include the formation of a tetrahedral intermediate and a subsequent intramolecular rearrangement. The phosphinoyl-protecting group can be removed by alcoholysis or by reduction with DIBAL-H.
- Zhang, Dapeng,Lian, Mingming,Liu, Jia,Tang, Shukun,Liu, Guangzhi,Ma, Cunfei,Meng, Qingwei,Peng, Haisheng,Zhu, Daling
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supporting information
p. 2597 - 2601
(2019/04/17)
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- Hydroxynitrile Lyase Isozymes from Prunus communis: Identification, Characterization and Synthetic Applications
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Biocatalysts originating from Badamu (Prunus communis) have been applied to catalyze the asymmetric synthesis of (R)-4-methylsulfanylmandelonitrile, a key building block of thiamphenicol and florfenicol. Here, four hydroxynitrile lyase (HNL) isozymes from Badamu were cloned and heterologously expressed in Pichia pastoris. The biochemical properties and catalytic performances of these isozymes were comprehensively explored to evaluate their efficiency and selectivity in asymmetric synthesis. Among then, PcHNL5 was identified with outstanding activity and enantioselectivity in asymmetric hydrocyanation. Under the optimized mild biphasic reaction conditions, seventeen prochiral aromatic aldehydes were converted to valuable chiral cyanohydrins with good yields (up to 94%) and excellent optical purities (up to >99.9% ee), which provide a facile access to numerous chiral amino alcohols, hypoglycemic agents, angiotension converting enzyme (ACE) inhibitors and β-blockers. This work therefore underlines the importance of discovering the most potent biocatalyst among a group of isozymes for converting unnatural substrates into value-added products. (Figure presented.).
- Zheng, Yu-Cong,Xu, Jian-He,Wang, Hui,Lin, Guo-Qiang,Hong, Ran,Yu, Hui-Lei
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p. 1185 - 1193
(2017/04/13)
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- Preparation method of alpha-hydroxypyridine by acetone cyanohydrin
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The invention relates to a preparation method of alpha-hydroxypyridine by acetone cyanohydrin, and relates to a preparation method of alpha-hydroxypyridine. The method solves the problems that the existing preparation method of the alpha-hydroxypyridine is low in yield, big in catalyst toxicity, high in price, complex in preparation method, and long in reaction time. The method includes steps of firstly, immersing cation exchange resin in 20% by weight of organic amine methanol solution; filtering, washing and drying the solution to obtain catalyst; secondly, dissolving acetone cyanohydrin and aromatic aldehyde in the methanol, and adding catalyst to react and obtain the alpha-hydroxypyridine; filtering the catalyst, depressurizing and evaporating methanol and acetone; extracting and separating the methanol and acetone; after drying, rotationally evaporating and removing ethyl acetate to obtain the alpha-hydroxypyridine. The method applies the simple and easily-prepared catalyst, and the reaction can be completed under room temperature condition; the reaction yield is up to over 95%. The operation method is simple and easy to practice, and the catalyst can be repeatedly used and is more applicable to the industrial production. The preparation method is applied to prepare alpha-hydroxypyridine.
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Paragraph 0046-0060
(2018/04/01)
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- Acceptorless and Base-free Dehydrogenation of Cyanohydrin with (η6-Arene)halide(Bidentate Phosphine)ruthenium(II) Complex
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Ruthenium-catalyzed dehydrogenation of cyanohydrins under acceptorless and base-free conditions was demonstrated for the first time in the synthesis of acyl cyanide. As opposed to the thermodynamically preferred elimination of hydrogen cyanide, the dehydrogenation of cyanohydrins could be kinetically controlled with ruthenium (II) bidentate phosphine complexes. The effects of the arene, phosphine ligands and counter anions were investigated in regard to catalytic activity and selectivity. Selective dehydrogenation can occur via β-hydride elimination with the experimentally observed [(alkoxide)Ru] complex. (Figure presented.).
- Kim, Kicheol,Moeljadi, Adhitya Mangala Putra,Hirao, Hajime,Hong, Soon Hyeok
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supporting information
p. 3292 - 3298
(2017/09/06)
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- Palladium-Catalyzed C(sp3)-C(sp2) Cross-Couplings of O -(α-Bromoacyl) Cyanohydrins with Boronic Acids: An Entry to Enantioenriched N -Acylated β-Amino Alcohols
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Suzuki-type cross-coupling of enantiomerically enriched O-(α-bromoacyl) cyanohydrins with aromatic boronic acids substituted with electron-withdrawing or electron-donating groups gave the expected coupling products in high yields without racemization. These substrates exhibit higher reactivities than analogous substrates lacking the nitrile function, probably as a result of π-coordination of the nitrile to palladium. Reduction of the nitrile group of the products, with accompanying intramolecular acyl transfer, provides access to biologically interesting N-acylated β-amino alcohols.
- Hertzberg, Robin,Dinér, Peter,Moberg, Christina
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p. 3175 - 3182
(2016/09/12)
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- High-Throughput Preparation of Optically Active Cyanohydrins Mediated by Lipases
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Cyanohydrins are versatile compounds with high applicability in organic synthesis; they are used as starting materials for the synthesis of other chemical targets with high industrial added value. Lipase-mediated kinetic resolution reactions are a promising route for the synthesis of optically active cyanohydrins. These reactions can be carried out through the acylation of cyanohydrins or the deacylation of cyanohydrin esters, with different biocatalysts and under different reaction conditions. Unfortunately, depending on the substrate structure, long reaction times can be required to achieve suitable enantiomeric excesses. In this context, we present a high-throughput protocol for the production of optically active cyanohydrins in continuous-flow mode. The products were obtained with moderate to good enantioselectivity (E values from 8 up to >200) and with productivity values from 2.4 to 8.7 times higher in continuous-flow mode than in batch mode. Moreover, the reaction times were reduced from hours in batch mode to minutes in continuous-flow mode.
- Thomas, Juliana Christina,Aggio, Bruno Bernardi,Marques de Oliveira, Alfredo Ricardo,Piovan, Leandro
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supporting information
p. 5964 - 5970
(2016/12/26)
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- Preparation method of 2-hydroxy acid ester
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The invention relates to a preparation method of 2-hydroxy acid ester and belongs to the technical field of organic synthesis. According to the preparation method of 2-hydroxy acid ester, 2-hydroxy alkyl cyanogens is taken as a raw material to be added to a reaction solution formed by hydrogen chloride, alcohol and water, and after reaction, 2-hydroxy acid ester is obtained. According to the preparation method of 2-hydroxy acid ester, use of a large amount of nonpolar solvent is not needed, and a target product can be obtained by a one-pot method, thus lowering production cost, improving production efficiency and the purify of the target product, and having energy-saving and environment-friendly effects.
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Paragraph 0040-0041
(2017/04/11)
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- Mechanochemical Strecker Reaction: Access to α-Aminonitriles and Tetrahydroisoquinolines under Ball-Milling Conditions
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A mechanochemical version of the Strecker reaction for the synthesis of α-aminonitriles was developed. The milling of aldehydes, amines, and potassium cyanide in the presence of SiO2gave the corresponding α-aminonitriles in good to high yields. The high efficiency of the mechanochemical Strecker-type multicomponent reaction allowed the one-pot synthesis of tetrahydroisoquinolines after a subsequent internal N-alkylation reaction.
- Hernández, José G.,Turberg, Mathias,Schiffers, Ingo,Bolm, Carsten
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supporting information
p. 14513 - 14517
(2016/10/03)
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- Br?nsted Acid-Catalyzed Cyanotritylation of Aldehydes by Trityl Isocyanide
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Cyanohydrins are versatile intermediates toward valuable organic compounds like α-hydroxy carboxylic acids, α-amino acids, and β-amino alcohols. Numerous protocols are available for synthesis of (O-protected) cyanohydrins, but all procedures invariably rely on the use of toxic cyanide sources. A novel cyanide-free synthesis of O-trityl protected cyanohydrins via a catalytic Passerini-type reaction involving aldehydes and trityl isocyanide is reported. The feasibility of a catalytic asymmetric reaction is demonstrated using chiral phosphoric acid catalysis.
- Cioc, Rǎzvan C.,Schuckman, Peter,Preschel, Hans D.,Vlaar, Tj?stil,Ruijter, Eelco,Orru, Romano V.A.
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supporting information
p. 3562 - 3565
(2016/08/16)
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- Active and Recyclable Catalytic Synthesis of Indoles by Reductive Cyclization of 2-(2-Nitroaryl)acetonitriles in the Presence of Co-Rh Heterobimetallic Nanoparticles with Atmospheric Hydrogen under Mild Conditions
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A cobalt-rhodium heterobimetallic nanoparticle-catalyzed reductive cyclization of 2-(2-nitroaryl)acetonitriles to indoles has been achieved. The tandem reaction proceeds without any additives under the mild conditions (1 atm H2 and 25 °C). This procedure could be scaled up to the gram scale. The catalytic system is significantly stable under these reaction conditions and could be reused more than ten times without loss of catalytic activity.
- Choi, Isaac,Chung, Hyunho,Park, Jang Won,Chung, Young Keun
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supporting information
p. 5508 - 5511
(2016/11/17)
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- A magnetic nanoparticle catalyzed eco-friendly synthesis of cyanohydrins in a deep eutectic solvent
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Magnetic Fe3O4 nanoparticles in deep eutectic solvents (DESs) have been regard as excellent catalysts for highly efficient cyanosilylation of various aldehydes and epoxides using trimethylsilyl cyanide TMSCN in high yields with excellent selectivity. Fe3O4 nanoparticles were synthesized and applied as a catalyst for the preparation of a wide variety of cyanohydrins (α-hydroxy nitriles and β-hydroxy nitriles) in readily available urea-choline chloride deep eutectic solvent DES as the most promising environmentally benign and cost-effective green solvent. Magnetic DES operates at very mild reaction conditions and can be easily recycled without significant loss of its catalytic activity.
- Azizi, Najmedin,Rahimi, Zahra,Alipour, Masoumeh
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p. 61191 - 61198
(2015/07/28)
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- A metalloligand appended with thiazole rings: Heterometallic {Co3+-Zn2+} and {Co3+-Cd2+} complexes and their heterogeneous catalytic applications
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This work describes a Co3+-based metalloligand containing appended thiazole rings and its reactions with secondary metal ions to produce heterometallic {Co3+-Zn2+} and {Co3+-Cd2+} complexes. Structural studies show that some of the appended thiazole rings from the metalloligand coordinate to secondary metal ions, whereas the remaining ones act as hydrogen-bond acceptors to metal-bound CH3OH or H2O molecules. These heterometallic complexes function as reusable heterogeneous catalysts for the ring-opening reactions of epoxides as well as cyanation and Knoevenagel condensation reactions of aldehydes. The catalytic results illustrate that the microenvironment remains intact during the catalysis and potentially enhances the substrate interaction with the Lewis acidic secondary metal ions.
- Bansal, Deepak,Hundal, Geeta,Gupta, Rajeev
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p. 1022 - 1032
(2015/06/24)
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- Three-Dimensional Heterometallic Coordination Networks: Syntheses, Crystal Structures, Topologies, and Heterogeneous Catalysis
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This work presents the synthesis of {Co3+-Zn2+} and {Co3+-Cd2+} heterometallic coordination networks. These networks are originated from two unique Co3+-based metalloligands containing appended arylcarboxylic acid groups at the strategically placed positions. Such appended arylcarboxylate groups coordinate the secondary metal ions, Zn2+ and Cd2+, to afford distinct three-dimensional networks. All four networks display orderly arrangement of secondary metal ions and unique network topologies including an unprecedented one. These networks have been shown to act as the heterogeneous and reusable catalysts for the Knoevenagel condensation reactions and cyanation reactions of assorted aldehydes. Cyanation reactions nicely demonstrate the substrate size-exclusion catalysis.
- Srivastava, Sumit,Aggarwal, Himanshu,Gupta, Rajeev
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p. 4110 - 4122
(2015/08/18)
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- Heterometallic coordination polymers: syntheses, structures and heterogeneous catalytic applications
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A metalloligand Na[Co(L1)2] (1) of the ligand H2L1 (N2,N6-bis(4,5-dihydrothiazol-2-yl)pyridine-2,6-dicarboxamide) offering appended thiazoline rings has been used for the synthesis of one-dimensional {Co3+-Zn2+} (2), {Co3+-Cd2+} (3) and {Co3+-Hg2+} (4) coordination polymers. 1 offers appended thiazoline rings having both soft sulphur and hard nitrogen donors. The crystal structures of 2 and 3 display the coordination of hard thiazoline-N donors to Zn2+ and Cd2+ ions. Interestingly, 4 illustrates the bonding through both hard thiazoline-N and soft thiazoline-S donors. The three heterometallic coordination polymers have been used as reusable heterogeneous catalysts for the ring-opening reactions of oxiranes and thiiranes; Knoevenagel condensation of benzaldehydes and benzothialdehydes; and cyanation reactions of aldehydes and carbothialdehydes. Our results demonstrate that the relative size and Lewis acidity of secondary metals potentially control the catalytic outcome via preferential interaction with the substrates.
- Bansal, Deepak,Pandey, Saurabh,Hundal, Geeta,Gupta, Rajeev
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p. 9772 - 9781
(2015/12/01)
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- Solid phase behavior in the chiral systems of various 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives
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The solid phase behavior of a series of monosubstituted F-, Cl-, Br-, I-, and CH3- and two 2,4-halogen-disubstituted 2-hydroxy-2-phenylacetic acid (mandelic acid) derivatives was investigated. The study includes detailed information about melting temperature, melting enthalpy, X-ray diffraction data, as well as selected binary phase diagrams of the respective chiral systems. Aside from the known metastable conglomerate 2-chloromandelic acid, evidence for two more metastable conglomerates was found.
- Von Langermann, Jan,Temmel, Erik,Seidel-Morgenstern, Andreas,Lorenz, Heike
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p. 721 - 728
(2015/03/30)
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- Nitrilases, nucleic acids encoding them and methods for making and using them
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The invention relates to nitrilases and to nucleic acids encoding the nitrilases. In addition methods of designing new nitrilases and method of use thereof are also provided. The nitrilases have increased activity and stability at increased pH and temperature.
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Page/Page column 67
(2016/01/09)
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- Synthesis of benzoyl cyanide through aerobic photooxidation of benzyl cyanide using carbon tetrabromide as a catalyst
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We developed a synthetic method toward benzoyl cyanide through aerobic photooxidation of benzyl cyanide in the presence of carbon tetrabromide under visible light irradiation with fluorescent lamps.
- Sugiura,Tachikawa,Nagasawa,Tada,Itoh
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p. 70883 - 70886
(2015/09/08)
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- P(NMe2)3-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
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A commercial phosphorus-based reagent (P(NMe2)3) mediates umpolung alkylation of methyl aroylformates with benzylic and allylic bromides, leading to either Barbier-type addition or ylide-free olefination products upon workup. The reaction sequence is initiated by a two-electron redox addition of the tricoordinate phosphorus reagent with an α-keto ester compound (Kukhtin-Ramirez addition). A mechanistic rationale is offered for the chemoselectivity upon which the success of this nonmetal mediated C-C bond forming strategy is based.
- Wang, Sunewang Rixin,Radosevich, Alexander T.
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supporting information
p. 3810 - 3813
(2015/08/18)
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- Mechanism-Based inactivation of human cytochrome p450 3A4 by two piperazine-Containing compounds
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Human cytochrome P450 3A4 (CYP3A4) is responsible for the metabolism of more than half of pharmaceutic drugs, and inactivation of CYP3A4 can lead to adverse drug-drug interactions. The substituted imidazole compounds 5-fluoro-2-[4-[(2-phenyl-1H-imidazol-5-yl) methyl]-1-piperazinyl]pyrimidine (SCH 66712) and 1-[(2-ethyl-4-methyl-1H-imidazol-5-yl)methyl]-4-[4-(trifluoromethyl)-2-pyridinyl]piperazine (EMTPP) have been previously identified as mechanism-based inactivators (MBI) of CYP2D6. The present study shows that both SCH 66712 and EMTPP are also MBIs of CYP3A4. Inhibition of CYP3A4 by SCH 66712 and EMTPP was determined to be con-centration, time, and NADPH dependent. In addition, inactivation of CYP3A4 by SCH 66712 was shown to be unaffected by the presence of electrophile scavengers. SCH 66712 displays type I binding to CYP3A4 with a spectral binding constant (Ks) of 42.9 ± 2.9 μM. The partition ratios for SCH 66712 and EMTPP were 11 and 94, respectively. Whole protein mass spectrum analysis revealed 1:1 binding stoichiometry of SCH 66712 and EMTPP to CYP3A4 and a mass increase consistent with adduction by the inactivators without addition of oxygen. Heme adduction was not apparent. Multiple monooxygenation products with each inactivator were observed; no other products were apparent. These are the first MBIs to be shown to be potent inactivators of both CYP2D6 and CYP3A4.
- Bolles, Amanda K.,Fujiwara, Rina,Briggs, Erran D.,Nomeir, Amin A.,Furge, Laura Lowe
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p. 1471 - 1475
(2014/12/11)
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- Mononuclear complexes of amide-based ligands containing appended functional groups: Role of secondary coordination spheres on catalysis
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Amide-based ligands H2L1, H2L2 and H2L3 containing thiazole, thiazoline and benzothiazole appended groups have been used to synthesize Zn2+ (1 and 3), Cd2+ complexes (2 and 4), and a Mn2+ complex (5). In all cases, potentially multidentate ligands create a meridional N3 coordination environment around the M(ii) ion whereas additional sites are occupied by labile nitrate ions in 1-4 and MeOH in 5. Interestingly, metal complexation caused the migration of protons from amidic N-H sites to the appended heterocyclic rings in complexes 1-4. Structural studies show that the protonated heterocyclic rings in these complexes create a hydrogen bond based cavity adjacent to the metal ion. Importantly, binding studies confirm that the substrates are bound within the complex cavity closer to the Lewis acidic metal in all complexes including the oxidation-sensitive Mn ion in complex 5. All complexes have been utilized as the reusable and heterogeneous catalysts for ring-opening reactions of assorted epoxides, cyanation reactions of various aldehydes, and epoxidation reactions of several olefins. This journal is
- Bansal, Deepak,Kumar, Gulshan,Hundal, Geeta,Gupta, Rajeev
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p. 14865 - 14875
(2015/02/19)
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- Kinetic resolution of mandelate esters via stereoselective acylation catalyzed by lipase PS-30
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By using lipase PS-30 as catalyst, the kinetic resolution of a series of racemic mandelate esters has been achieved via stereoselective acylation. The value of kinetic enantiomeric ratio (E) reached up to 197.5. Substituent effect is briefly discussed.
- Chen, Peiran,Yang, Wenhong
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supporting information
p. 2290 - 2294
(2014/04/17)
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- Three-dimensional {Co3+-Zn2+} and {Co 3+-Cd2+} networks originated from carboxylate-rich building blocks: Syntheses, structures, and heterogeneous catalysis
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The present work shows the utilization of Co3+ complexes appended with either para- or meta-arylcarboxylic acid groups as the molecular building blocks for the construction of three-dimensional {Co 3+-Zn2+} and {Co3+-Cd2+} heterobimetallic networks. The structural characterizations of these networks show several interesting features including well-defined pores and channels. These networks function as heterogeneous and reusable catalysts for the regio- and stereoselective ring-opening reactions of various epoxides and size-selective cyanation reactions of assorted aldehydes.
- Kumar, Girijesh,Gupta, Rajeev
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p. 10773 - 10787
(2013/10/22)
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- NaCN/DOWEX(R)50WX4: A convenient system for synthesis of cyanohydrins from aldehydes
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A variety of cyanohydrins were prepared from Aldehydes with sodium cyanide and DOWEX(R)50WX4 in a convenient procedure.
- Sofighaderi, Sargol,Setamdideh, Davood
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p. 1135 - 1137
(2014/03/21)
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- A simple separation method for (S)-hydroxynitrile lyase from cassava and its application in asymmetric cyanohydrination
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Using an acetone precipitation method, crude (S)-hydroxynitrile lyase [(S)-MeHNL] was separated from Munihot esculenta (cassava) leaves, and used directly as biocatalyst to catalyze asymmetric cyanohydrination and produce cyanohydrins with enantiomeric purities (≥90% ee) significantly greater than those previously reported. The use of a water/i-Pr2O system with an enzyme, NaCN, and appropriate amounts of acetic acid is crucial in improving the stereoselectivity of cyanohydrin formation by minimizing the non-enzymatic reaction and the racemization of the chiral products. The proposed isolation method for crude (S)-MeHNL has a high value because of its simplicity, and low cost as well as the high activity of the crude (S)-MeHNL.
- Zheng, Zubiao,Zi, Yan,Li, Zhongzhou,Zou, Xinzhuo
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p. 434 - 439
(2013/06/27)
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- The preparation of various new heterocyclic compounds via cyclization of substituted derivatives of phenacyl esters of hydrazonoacetic acid
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A procedure for the preparation of derivatives of phenacyl hydrazonopropanoates and their application in the synthesis of various heterocycles has been developed. Not only is the preparation of indole derivatives described, but also a new method for the preparation of previously unknown pyridazine derivatives.
- Melnicky, Radek,Grepl, Martin,Lycka, Antonin,Bertolasi, Valerio,Kvapil, Lubomir,Dvorakova, Barbora,Hradil, Pavel
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p. 2447 - 2457
(2013/09/23)
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- Metal or ammonium alginates as Lewis base catalysts for the 1,2-addition of silyl nucleophiles to carbonyl compounds
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Several metal (Na+, Ca2+) or ammonium (n-Bu 4N+) derivatives of alginic acid, an abundant bio-polymer obtained from the cell walls of brown algae, were synthesized. Their potential to act as organocatalysts to catalyze the 1,2-addition of various silyl derivatives to carbonyl compounds was evaluated for the first time. Ammonium alginate 1h is able to promote the reaction in modest to good isolated yields (up to 98%) affording access to a large range of substrates (β-cyano alcohols or ester, β-substituted methylacrylate or acrylonitrile, and cyanohydrin) by using only 5 mol % of catalyst.
- Verrier, Cécile,Oudeyer, Sylvain,Dez, Isabelle,Levacher, Vincent
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supporting information; experimental part
p. 1958 - 1960
(2012/05/19)
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- An efficient cyanosilylation of aldehydes with trimethylsilyl cyanide catalysed by MgI2 etherate
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A convenient procedure for the synthesis of cyanohydrins by the addition of trimethylsilyl cyanide to aromatic aldehydes, heteroaromatic aldehydes, aliphatic aldehydes and unsaturated aldehydes catalysed by MgI2 etherate (MgI2(OEt2)n) in good to excellent yields is described.
- Wang, Yanping,Feng, Meiling,Liu, Yingshuai,Zhang, Xingxian
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p. 566 - 567,2
(2020/09/16)
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- Direct crystallographic observation of catalytic reactions inside the pores of a flexible coordination polymer
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A new flexible porous coordination polymer (PCP), {[Gd2(L) 3(dmf)4]·4 DMF·3 H2O}n (1), was synthesized under solvothermal condition by reacting [Gd(NO 3)3]·6 H2O with the ligand 2,6,2',6'-tetranitro-biphenyl-4,4'-dicarboxylic acid (H2L). Compound 1 had a 3D coordination polymeric structure with two types of 1D channels (A and B) that were occupied by DMF and water molecules. When crystals of 1 were separately exposed to vapors of various aromatic aldehydes, either the lattice or both the lattice and metal-bound solvent molecules were replaced by aldehyde molecules. The aldehyde molecules inside the pores spontaneously underwent cyanosilylation and Knoevenagel condensation reactions upon exposure to vapors of trimethylsilyl cyanide and malononitrile, respectively. These reactions took place at ambient temperature and pressure. Moreover, both the reactants and the products translocated from one cavity to another. The products that occupied the cavity were expunged upon exposure to the vapors of an aldehyde. Because crystallinity was maintained during these chemical transformations, direct crystallographic observation was possible. Herein, we showed that confinement of the reactants inside the void spaces of the PCP led to the products; we also assessed catalytic activities of this PCP in bulk quantities. Copyright
- Das, Raj Kumar,Aijaz, Arshad,Sharma, Manish K.,Lama, Prem,Bharadwaj, Parimal K.
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experimental part
p. 6866 - 6872
(2012/07/31)
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- Silylcyanation of aldehydes, ketones, and imines catalyzed by a 6,6'-bis-sulfonamide derivative of 7,7'-dihydroxy-8,8'-biquinolyl (azaBINOL)
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6,6'-Bis(methylaminosulfonyl)-7,7'-dihydroxy-8,8'-biquinolyl (3) catalyzes (5-10 mol-%) the addition of trimethylsilyl cyanide to aldehydes (aryl, alkyl, and α,β-unsaturated; 42-92 % yields), ketones (aryl alkyl, dialkyl; 22-82 % yields), and N-benzylaldimines (14-78 % yields) in toluene (0 °C or room temp.) to give the expected cyanohydrin and Strecker adducts following desilylation. Among a series of closely related compounds lacking any one of their defining structural features, bis-sulfonamide 3 and its N,N'-dimethyl derivative are exceptional in catalyzing the silylcyanation of benzaldehyde in the absence of all other additives. Hammett analysis of the competitive silylcyanation of para-substituted benzaldehydes catalyzed by 3 showed a linear free-energy relationship (R2 = 0.928) with a modest positive reaction constant (ρ = +1.52). X-ray diffraction analysis of (±)-3 indicated a cisoid biaryl conformation and the existence of an intramolecular hydrogen bond between C7'-OH and C7-O. Resolution of (±)-3 was achieved by HPLC separation of its tetravalerate derivative on a chiral stationary phase. The absolute configurations of the optical isomers of 3 were assigned by correlation of the ECD spectra with those of related biquinolyls of known configuration. The silylcyanation of aldehydes catalyzed by (-)-(aR)-3 leads to cyanohydrins with a preference for the (S)-configured product with an ee of 10 %. The organocatalytic action of 3 is ascribed to hydrogen bonding and Bronsted acid catalysis effects that are dependent on its acidifying sulfonamide groups, general base capability, and interannular proximity effects made possible by the biaryl structure. Copyright
- Sephton, Selena Milicevic,Wang, Chao,Zakharov, Lev N.,Blakemore, Paul R.
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experimental part
p. 3249 - 3260
(2012/08/08)
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- A single-step, mild, neutral, catalyst-free method for cyanohydrin synthesis
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A wide variety of carbonyl compounds can be transformed to their corresponding cyanohydrins in a single step using a dimethyl sulfoxide (DMSO)-water system in excellent yields (75-94%). The major advantages of this system are that the reaction conditions are mild and neutral; the reaction proceeds without catalyst and gives the corresponding cyanohydrins in short time (15-120 min).
- Degani, Mariam S.,Kakwani, Manoj D.,Palsule Desai, Nutan H.,Bairwa, Ranjeet
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experimental part
p. 461 - 465
(2012/06/15)
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- Redox-neutral α-cyanation of amines
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α-Aminonitriles inaccessible by traditional Strecker chemistry are obtained in redox-neutral fashion by direct amine α-cyanation/N-alkylation or alternatively, α-aminonitrile isomerization. These unprecedented transformations are catalyzed by simple carboxylic acids.
- Ma, Longle,Chen, Weijie,Seidel, Daniel
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supporting information
p. 15305 - 15308
(2012/10/29)
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- Asymmetric induction by helical poly(amino acid)s in cyanosilylation of aldehydes
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It was first demonstrated that helical poly(amino acid)s have an ability to induce enantioselectivity in the cyanosilylation of aldehydes. The helicity of poly(amino acid)s and the N-terminal amino group were essential for the enantioinduction of the reaction.
- Akagawa, Kengo,Kudo, Kazuaki
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supporting information
p. 5981 - 5983,3
(2020/08/20)
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- Cyanative self-condensation of aromatic aldehydes promoted by VO(O iPr)3-Lewis base as a cooperative catalyst
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Self-condensation of aromatic aldehydes with trimethylsilyl cyanide proceeded by the cooperative catalytic effect of VO(OiPr)3 and a Lewis base to give the corresponding O-acylated cyanohydrins. The reaction conversion and selectivity were strongly dependent on the solvent used, the Lewis base, and the presence of oxygen. All the nine kinds of aromatic aldehydes considered herein afforded the O-acylated cyanohydrins with excellent selectivity under an O2 atmosphere.
- Kodama, Koichi,Kawamata, Hiroaki,Takahashi, Naoya,Hirose, Takuji
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p. 9440 - 9446
(2013/01/15)
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- One-pot three-component reaction: Synthesis of substituted β-cyanocarbonyls in aqueous media
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An environmentally friendly and simple method for the synthesis of alkyl nitriles or β-cyanocarbonyls via a one-pot three-component reaction of Meldrum's acid, aldehydes and sodium cyanide in water, without using any catalyst or activation at room temperature is reported.
- Soleimani, Ebrahim,Khodaei, Mohammad Mehdi,Taheri Kal Koshvandi, Afsaneh
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scheme or table
p. 273 - 277
(2012/06/30)
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- Cooperative thiourea-Bronsted acid organocatalysis: Enantioselective cyanosilylation of aldehydes with TMSCN
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We report a new thiourea - Bronsted acid cooperative catalytic system for the enantioselective cyanosilylation of aldehydes with yields up to 90% and enantioselectivities up to 88%. The addition of an achiral acid was found to be crucial for high asymmetric induction. Mechanistic investigations using a combination of NMR, ESI-MS, and density functional theory computations (including solvent corrections) at the M06/6-31G(d,p) level of theory suggest that the key catalytic species results from the cooperative interaction of bifunctional thioureas and an achiral acid that form well-defined chiral hydrogen-bonding environments.
- Zhang, Zhiguo,Lippert, Katharina M.,Hausmann, Heike,Kotke, Mike,Schreiner, Peter R.
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p. 9764 - 9776
(2012/01/03)
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- α-Pinene-type chiral Schiff bases as tridentate ligands in asymmetric addition reactions
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A group of tridentate Schiff bases derived from (+)-α-pinene were synthesized. The steric effects in the transition state, the importance of π-π stacking interactions as well as the electronic effects of aryl aldehydes according to Hammett constant values in the enantioselective addition of Et2Zn to aldehydes with the use of Schiff bases as chiral ligands are described. Also, a variety of aldehydes were cyanated using a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases. The influence of a conjugated double-bond in the cyanation substrates on enantioselectivity was observed. The chemical structures of the chiral Schiff base-titanium alkoxide complexes are discussed based on their 1H and 13C NMR spectra. 3D models of the Zn2-complex catalyst and Ti-complex catalyst containing α-pinane-type Schiff bases based on X-ray diffraction experiments are postulated. The models presented were consistent with the reported chirality of the addition product and observed ee.
- Jaworska, Magdalena,Blocka, Ewelina,Kozakiewicz, Anna,Welniak, Miroslaw
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experimental part
p. 648 - 657
(2011/07/08)
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- Two-dimensional rhombus grid coordination polymer showing heterogeneous catalytic activities
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A coordination polymer, {[Cd(L)2(DMF)2] ·(ClO4)2·(2DMF)}n (1) (L = bis-(4-imidazol-1-yl-phenyl)-diazene) has been synthesized at room temperature. The polymer forms a two-dimensional (2D) rhombus-grid sheet structure. These 2D sheets are stacked in ABAB... mode with an inter-planar spacing of 3.729 . Each Cd(II) ion is equatorially bonded to four imidazole N atoms belong to four different ligand units while O atoms from two DMF molecules occupy the axial sites. Two ClO4- counter anions as well as two DMF molecules occupy the void space in each rhombus grid. This compound catalyzes cyanosilylation reactions of aromatic aldehydes in dichloromethane under mild conditions in heterogeneous fashion. On heating 1 at 120 °C for 4 h, all DMF molecules are lost and the ClO4- anions move out of the void space to occupy the axial sites on the metal to yield, de-solvated {[Cd(L)2(ClO4)2]}n (1) without losing crystallinity. De-solvated 1 exhibits heterogeneous catalytic activity in several Knoevenagel condensation reactions at RT.
- Sharma, Manish K.,Singh, Prabal P.,Bharadwaj, Parimal K.
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experimental part
p. 6 - 10
(2011/07/30)
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- Enantioselective O-acetylcyanation/cyanoformylation of aldehydes using catalysts with built-in crown ether-like motif in chiral macrocyclic V(V) salen complexes
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Chiral macrocyclic V(V) salen complexes 1a-f derived from macrocyclic ligands obtained by the reaction of 1R,2R-(-) diaminocyclohexane/(1R,2R)-(+)-1, 2-diphenylethylenediamine with bis-aldehydes 2 and 3 were synthesized and used as efficient catalysts in asymmetric cyanation reactions. The V(V) catalysts demonstrated excellent performance (product yields and ees up to 99%) with potassium cyanide (KCN) and sodium cyanide (NaCN). The catalytic system also performed very well with a safer source of cyanide-ethyl cyanoformate to give cyanohydrin carbonates in excellent yield and ee (up to 97%). The V(V) macrocyclic salen complex 1b retained its performance at multi-gram level and was conveniently recycled for a number of times.
- Khan, Noor-Ul H.,Sadhukhan, Arghya,Maity, Nabin C.,Kureshy, Rukhsana I.,Abdi, Sayed H.R.,Saravanan,Bajaj, Hari C.
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body text
p. 7073 - 7080
(2011/10/07)
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