- A Zn(ii)-functionalized COF as a recyclable catalyst for the sustainable synthesis of cyclic carbonates and cyclic carbamates from atmospheric CO2
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A simple covalent organic framework (COF) bearing β-ketoenamine units as a potential heterogeneous ligand for ZnII-catalyzed fixation and transformation of CO2 into value-added chemicals is reported. Catalytic investigations convincingly demonstrated that the ZnII-functionalized covalent organic framework (Zn@TpTta) exhibits perfect catalytic activity in the fixation of CO2 for diverse epoxides with various substituents under sustainable conditions. A variety of terminal epoxides and slightly more complicated disubstituted epoxides were transformed into the corresponding cyclic carbonates with satisfactory to excellent yields (i.e., 69 to 99% yield) upon exposure to CO2 (1 atm) under solvent-free conditions (sustainable approach). On the other hand, this ZnII-loaded covalent organic framework also displayed excellent performance in facilitating atmospheric cyclizative CO2 capture, which led to the formation of diverse cyclic carbamates (i.e., 61 to 94% yield) from unsaturated amine systems using N-iodosuccinimide (NIS) as an iodinating agent and PEG-400 as a biodegradable and green polymeric solvent under base-free conditions (sustainable approach). The newly synthesized COF-based catalyst, namely, Zn@TpTta, has been completely characterized by SEM (scanning electron microscopy), EDX (energy dispersive X-ray analysis), HRTEM (high-resolution transmission electron microscopy), BET (Brunauer-Emmett-Teller), PXRD (powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), ICP (inductively coupled plasma), etc. More intriguingly, the catalytic system could be recycled over five times without a noticeable loss of catalytic performance for both reactions. This study opens an avenue for the Zn(ii) embedded COF as a promising platform for regulating regioselectivity.
- Ghosh, Swarbhanu,Islam, Sk. Manirul,Sarkar, Somnath
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p. 1707 - 1722
(2022/03/02)
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- A metagenomics approach for new biocatalyst discovery: Application to transaminases and the synthesis of allylic amines
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Transaminase enzymes have significant potential for the sustainable synthesis of amines using mild aqueous reaction conditions. Here a metagenomics mining strategy has been used for new transaminase enzyme discovery. Starting from oral cavity microbiome samples, DNA sequencing and bioinformatics analyses were performed. Subsequent in silico mining of a library of contiguous reads built from the sequencing data identified 11 putative Class III transaminases which were cloned and overexpressed. Several screening protocols were used and three enzymes selected of interest due to activities towards substrates covering a wide structural diversity. Transamination of functionalized cinnamaldehydes was then investigated for the production of valuable amine building blocks.
- Baud, Damien,Jeffries, Jack W. E.,Moody, Thomas S.,Ward, John M.,Hailes, Helen C.
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p. 1134 - 1143
(2017/08/14)
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- Selectivity control by silver catalysts in the cycloisomerization of 1,6-enynes derived from propiolamides
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Silver-catalyzed cycloisomerizations of 1,6-enynes derived from propiolamides led to a selective formation of Alder-ene type 1,4-dienes. Interestingly, AgNTf2 outperformed gold or platinum catalysts in terms of selectivity and reactivity, providing the 1,4-dienes at room temperature. The presence of C(5) carbonyl group in combination with Ag salts is key to the selectivity and the β-oxo coordinated silver carbenoids were proposed as an intermediate based on the reaction profiles.
- Koo, Jaeyoung,Park, Hyun-Sub,Shin, Seunghoon
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supporting information
p. 834 - 839
(2013/02/25)
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- Cyclizative atmospheric CO2 fixation by unsaturated amines with t-BuOI leading to cyclic carbamates
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A cyclizative atmospheric CO2 fixation by unsaturated amines such as allyl and propargyl amines under mild reaction conditions, efficiently leading to cyclic carbamates bearing a iodomethyl group, have been developed utilizing tert-butyl hypoiodite (t-BuOI).
- Takeda, Youhei,Okumura, Sota,Tone, Saori,Sasaki, Itsuro,Minakata, Satoshi
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p. 4874 - 4877,4
(2020/09/16)
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- Discovery of a cytokinin deaminase
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An enzyme of unknown function within the amidohydrolase superfamily was discovered to catalyze the hydrolysis of N-6-substituted adenine derivatives, several of which are cytokinins. Cytokinins are a common type of plant hormone and N-6-substituted adenines are also found as modifications to tRNA. Patl2390, from Pseudoalteromonas atlantica T6c, was shown to hydrolytically deaminate N-6-isopentenyladenine to hypoxanthine and isopentenylamine with a k cat/Km of 1.2 × 107 M-1 s -1. Additional substrates include N-6-benzyl adenine, cis- and trans-zeatin, kinetin, O-6-methylguanine, N-6-butyladenine, N-6-methyladenine, N,N-dimethyladenine, 6-methoxypurine, 6-chloropurine, and 6-thiomethylpurine. This enzyme does not catalyze the deamination of adenine or adenosine. A comparative model of Patl2390 was computed using the three-dimensional crystal structure of Pa0148 (PDB code 3PAO) as a structural template, and docking was used to refine the model to accommodate experimentally identified substrates. This is the first identification of an enzyme that will hydrolyze an N-6-substituted side chain larger than methylamine from adenine.
- Goble, Alissa M.,Fan, Hao,Sali, Andrej,Raushel, Frank M.
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experimental part
p. 1036 - 1040
(2012/05/20)
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- GOLD CATALYZED HYDROAMINATION OF ALKYNES AND ALLENES
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Methods are provided for the catalytic hydroamination of compounds having an alkyne or allene functional group, in which the compound is contacted with ammonia or an amine in the presence of a catalytic amount of a gold complex under conditions sufficient for hydroamination to occur.
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Page/Page column 21; 24; 2/13
(2010/01/29)
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- Homogeneous catalytic hydroamination of alkynes and allenes with ammonia
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(Chemical Equation Presented) A golden ticket to the synthesis of reactive nitrogen-containing compounds, such as imines, enamines, and allyl amines, through the addition of NH3 to unsaturated bonds is the cationic cyclic (alkyl)-(amino)carbene-gold(I) catalyst shown in blue (Dipp=diisopropylphenyl). An ideal initial step for the preparation of simple bulk chemicals, this reaction is also useful for the synthesis of more complex molecules (see examples).
- Lavallo, Vincent,Frey, Guido D.,Donnadieu, Bruno,Soleilhavoup, Michele,Bertrand, Guy
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experimental part
p. 5224 - 5228
(2009/04/11)
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- Structure-selectivity relationship in the chemoselective hydrogenation of unsaturated nitriles
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Several unsaturated nitriles of various structures (cinnamonitrile, cyclohex-1-enyl-acetonitrile, acrylonitrile, 3,3-dimethyl-acrylonitrile, geranylnitrile, and 2- and 3-pentenenitrile) with different substituents at the double bond were hydrogenated over
- Kukula, Pavel,Koprivova, Klara
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p. 161 - 171
(2007/10/03)
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- Chemoselective hydrogenation of α,β-unsaturated nitriles
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The chemoselective hydrogenation of cinnamonitrile to 3-phenylallylamine proceeds with up to 80% selectivity at conversions of > 90% with Raney cobalt and up to 60% selectivity with Raney nickel catalysts. Best results were obtained with a doped Raney cobalt catalyst (RaCo/Cr/Ni/Fe 2724) in ammonia saturated methanol at 100°C and 80 bar. Major problems are the formation of hydrocinnamonitrile and of secondary amines, and overreduction to 3-phenylpropylamine. Important parameters are the catalyst type and composition, the solvent type and the presence and concentration of ammonia. The catalytic system tolerates functional groups like OH, OMe, Cl, C=O, but not aromatic nitro groups. Preliminary experiments indicate that other unsaturated nitriles with di- or trisubstituted C=C bonds are also suitable substrates.
- Kukula, Pavel,Studer, Martin,Blaser, Hans-Ulrich
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p. 1487 - 1493
(2007/10/03)
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- Amine and amidine containing compounds as weight reducing agents
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Use of amine and amidine containing compounds of formula (I) such as galegine and related substituted amine and amidine containing compounds as agents for reducing weight in mammals, pharmaceutical formulations containing a compound of formula (I) and methods of attaining weight reduction in mammals.
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- Thermolysis of N-Allylic 1,2,4-Triazoles
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A number of 4-allylic substituted 3,5-diphenyl-4H-1,2,4-triazoles were thennolyzed at 315-320° in evacuated glass ampoules. The main reaction in the melt was rearrangement to the corresponding 1-substituted triazoles, which appeared to proceed via competing SN2 and SN2′ mechanisms. The allylic systems were observed to undergo [2,3]-allyl walk reactions between the 1- and 2-ring positions. Allyl to vinyl isomerization also took place. Substitution of the allylic moiety increased the rate of reaction but decreased the rate of isomerization of allylic to the vinylic substituted triazoles. The 4-vinyl substituted triazoles were inert under the reaction conditions. Some triazoles were converted into substituted pyridines. This was proposed to proceed via nitrogen extrusion and formation of a 1,3-dipolar intermediate (nitrile ylide) which added intramolecularly to the allyl moiety and subsequently aromatized to the pyridine.
- Carlsen, Per H. J.,Jorgensen, Kare B.
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p. 797 - 806
(2007/10/03)
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- Palladium(0)-Catalyzed Azidation of Allyl Esters. Selective Synthesis of Allyl Azides, Primary Allylamines, and Related Compounds
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Palladium(0)-catalyzed reaction of allyl esters such as phosphates, carbonates, and carboxylates with sodium azide gives allyl azides.The azidation proceeds with retention of configuration at the allylic carbon.Optically active (R)-(E)-(+)-4-phenyl-3-buten-2-yl azide (19) is obtained from (R)-(E)-(+)-4-phenyl-3-buten-2-yl acetate (18) stereoselectively.Sequential substitution of (Z)-4-acetoxy-2-buten-1-yl diethyl phosphate (24) with nucleophiles and subsequently azide ion gives (E)-4-substituted-2-buten-1-yl azides 27.The reaction of allyl azides with triphenylphosphine gives iminotriphenylphosphoranes, which are versatile synthetic intermediates of primary allylamines, N-allylamines, and N-allylamides.Treatment of allyl azides with triphenylphosphine and subsequently with aqueous ammonium solution gives primary allylamines.Other synthetic applications of allyl azides are also described.
- Murahashi, Shun-Ichi,Taniguchi, Yuki,Imada, Yasushi,Tanigawa, Yoshio
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p. 3292 - 3303
(2007/10/02)
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- Synthetic studies in the α-kainic acid (2,3-trans,3,4-cis-2-carboxy- 4-isopropenylpyrrolidin-3-ylacetic acid) series
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The synthesis of (±)-cis- and (±)-trans-4- isopropenylpyrrolidin-3-ylacetic acids and the attempted synthesis of (±)-2,3-trans,3,4-cis-2-carboxy-4-isopropenylpyrrolidin-3-ylacetic acid, α-kainic acid, by intramolecular ene reactions are described. The ene cyclisation reaction has been shown to be kinetically controlled with the relative stabilities of the transition states controlling the product distribution. No isomerisation of starting diene or product pyrrolidine occurs under the conditions of the reaction.
- Kennewell, Peter D.,Matharu, Saroop S.,Taylor, John B.,Sammes, Peter G.
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p. 2542 - 2548
(2007/10/02)
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