- Identification of Acyl Chain Oxidation Products upon Thermal Treatment of a Mixture of Phytosteryl/-stanyl Linoleates
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A mixture of phytosterols/-stanols, consisting of 75% β-sitosterol, 12% sitostanol, 10% campesterol, 2% campestanol, and 1% others, was esterified with linoleic acid. The resulting mixture of phytosteryl/-stanyl linoleates was subjected to thermal oxidation at 180 °C for 40 min. A silica solid-phase extraction was applied to separate a fraction containing the nonoxidized linoleates and nonpolar degradation products (heptanoates, octanoates) from polar oxidation products (oxo- and hydroxyalkanoates). In total, 15 sitosteryl, sitostanyl, and campesteryl esters, resulting from oxidation of the acyl chain, could be identified by GC-FID/MS. Synthetic routes were described for authentic reference compounds of phytosteryl/-stanyl 7-hydroxyheptanoates, 8-hydroxyoctanoates, 7-oxoheptanoates, 8-oxooctanoates, and 9-oxononanoates, which were characterized by GC-MS and two-dimensional NMR spectroscopy. The study provides data on the formation and identities of previously unreported classes of acyl chain oxidation products upon thermal treatment of phytosteryl/-stanyl fatty acid esters.
- Wocheslander, Stefan,Eisenreich, Wolfgang,Scholz, Birgit,Lander, Vera,Engel, Karl-Heinz
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Read Online
- Ultrasound-assisted synthesis and in vitro antimicrobial activity of novel 5-oxo-2-pyrrolidinecarboxamides and 7-oxo-2-azepanecarboxamides
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A facile one-pot reaction has been set up for the synthesis of novel 5-oxo-2-pyrrolidinecarboxamides and 7-oxo-2-azepanecarboxamides 4a-j from three-component reaction of keto carboxylic acids 1a-d, various primary amines 2a-b and isocyanides 3a-b under ultrasound irradiation. The present protocol offers attractive characteristics such as easy handling methodology, good-to-excellent yields, environmental friendliness, clean reaction, higher atom economy, convenient operation, and shorter reaction time. The newly synthesized 5-oxo-2-pyrrolidinecarboxamides and 7-oxo-2-azepanecarboxamides 4a-j have been screened for their antimicrobial activity and the majority of these cyclic amides exhibited weak antimicrobial activity.
- Jassem, Ahmed Majeed,Chen, Beining
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p. 3575 - 3586
(2021/03/26)
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- Regioselective Hydroformylation of Internal and Terminal Alkenes via Remote Supramolecular Control
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Regioselective catalytic transformations using supramolecular directing groups are increasingly popular as it allows for control over challenging reactions that may otherwise be impossible. In most examples the reactive group and the directing group are close to each other and/or the linker between the directing group is very rigid. Achieving control over the regioselectivity using a remote directing group with a flexible linker is significantly more challenging due to the large conformational freedom of such substrates. Herein, we report the redesign of a supramolecular Rh–bisphosphite hydroformylation catalyst containing a neutral carboxylate receptor (DIM pocket) with a larger distance between the phosphite metal binding moieties and the DIM pocket. For the first time regioselective conversion of internal and terminal alkenes containing a remote carboxylate directing group is demonstrated. For carboxylate substrates that possess an internal double bond at the Δ-9 position regioselectivity is observed. As such, the catalyst was used to hydroformylate natural monounsaturated fatty acids (MUFAs) in a regioselective fashion, forming of an excess of the 10-formyl product (10-formyl/9-formyl product ratio of 2.51), which is the first report of a regioselective hydroformylation reaction of such substrates.
- Linnebank, Pim R.,Ferreira, Stephan Falc?o,Kluwer, Alexander M.,Reek, Joost N. H.
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supporting information
p. 8214 - 8219
(2020/06/21)
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- Rational Redesign of a Regioselective Hydroformylation Catalyst for 3-Butenoic Acid by Supramolecular Substrate Orientation
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Rational design of ligands for regioselective transformations is one of the long pursuing targets in the field of transition metal catalysis. In the current contribution, we report OrthoDIMphos (L2), a ligand that was designed for regioselective hydroformylation of 3-butenoic acid and its derivatives. The previously reported ParaDIMphos (L1) based hydroformylation catalyst was very selectively producing the linear aldehyde when substrates were bound in its pocket via hydrogen bonding. However, the distance between the binding site and the rhodium center was too large to also address 3-butenoic acid and its derivatives. We therefore designed OrthoDIMphos (L2) as new ligand which has a shorter distance between the DIM-receptor and the catalytic center. The OrthoDIMphos (L2) based catalyst displays high regioselectivity in the hydroformylation of 3-butenoic acid and challenging internal alkene analogue (l/b up to 84, TON up to 630), which cannot be achieved with the ParaDIMphos (L1) catalyst. Detailed studies show that the OrthoDIMphos (L2) based catalyst forms a dimeric structure, in which the two ligands coordinate to two different rhodium metals. Substrate binding to the DIM-receptor is required to break up the dimeric structure, and as only the monomeric analogue is a selective catalyst, the outcome of the reaction is dependent on substrate concentration used in catalysis.
- Bai, Shao-Tao,Sinha, Vivek,Kluwer, Alexander M.,Linnebank, Pim R.,Abiri, Zohar,de Bruin, Bas,Reek, Joost N. H.
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p. 5322 - 5329
(2019/05/10)
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- CATIONIC LIPIDS FOR NUCLEIC ACID DELIVERY AND PREPARATION THEREOF
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The present invention provides cationic lipids and lipid nanoparticle formulations comprising these lipids, alone or in combination with other lipids. These lipid nanoparticles may be formulated with nucleic acids to facilitate their intracellular delivery both in vitro and for therapeutic applications. The present invention also provides methods of chemical synthesis of these lipids, lipid nanoparticle preparation and formulation with nucleic acids.
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- CATALYTIC CARBOXYLATION OF ACTIVATED ALKANES AND/OR OLEFINS
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The present invention relates to a method of reacting starting materials with an activating group, namely alkanes carrying a leaving group and/or olefins, with carbon dioxide under transition metal catalysis to give carboxyl group-containing products. It is a special feature of the method of the present invention that the carboxylation predominantly takes place at a preferred position of the molecule irrespective of the position of the activating group. The carboxylation position is either an aliphatic terminus of the molecule or it is a carbon atom adjacent to a carbon carrying an electron withdrawing group. The course of the reaction can be controlled by appropriately choosing the reaction conditions to yield the desired regioisomer.
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Page/Page column 65; 66; 67
(2018/02/28)
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- Remote carboxylation of halogenated aliphatic hydrocarbons with carbon dioxide
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Catalytic carbon-carbon bond formation has enabled the streamlining of synthetic routes when assembling complex molecules. It is particularly important when incorporating saturated hydrocarbons, which are common motifs in petrochemicals and biologically relevant molecules. However, cross-coupling methods that involve alkyl electrophiles result in catalytic bond formation only at specific and previously functionalized sites. Here we describe a catalytic method that is capable of promoting carboxylation reactions at remote and unfunctionalized aliphatic sites with carbon dioxide at atmospheric pressure. The reaction occurs via selective migration of the catalyst along the hydrocarbon side-chain with excellent regio- and chemoselectivity, representing a remarkable reactivity relay when compared with classical cross-coupling reactions. Our results demonstrate that site-selectivity can be switched and controlled, enabling the functionalization of less-reactive positions in the presence of a priori more reactive ones. Furthermore, we show that raw materials obtained in bulk from petroleum processing, such as alkanes and unrefined mixtures of olefins, can be used as substrates. This offers an opportunity to integrate a catalytic platform en route to valuable fatty acids by transforming petroleum-derived feedstocks directly.
- Juliá-Hernández, Francisco,Moragas, Toni,Cornella, Josep,Martin, Ruben
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- MATERIALS AND METHODS OF PRODUCING 7-CARBON MONOMERS
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This document describes materials and methods for producing 7-hydroxyheptanoic acid using a β-ketothiolase or a synthase and an alcohol O-acetyltransferase to form a 7-acetyloxy-3-oxoheptanoyl-CoA intermediate. This document describes biochemical pathways for producing 7-hydroxyheptanoic acid using a β-ketothiolase or a synthase and an alcohol O-acetyltransferase to form a 7-acetyloxy-3-oxoheptanoyl-CoA intermediate. 7-hydroxyheptanoic acid can be enzymatically converted to pimelic acid, 7-aminoheptanoic acid, heptamethylenediamine or 1,7 heptanediol. This document also describes recombinant hosts producing 7-hydroxyheptanoic acid as well as pimelic acid, 7-aminoheptanoic acid, heptamethylenediamine and 1,7 heptanediol.
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Page/Page column 52; 53
(2016/07/27)
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- Synthesis of a series of hydroxycarboxylic acids as standards for oxidation of nonanoic acid
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The synthesis of a series of nonanoic acids hydroxylated in terminal,ω-1,ω-2,ω-3 positions is described. These compounds will be employed as useful standards for the study of enzymatic and microbiological oxidation of nonanoic acid.
- Rajabi, Mehdi,Lanfranchi, Moreno,Campo, Federica,Panza, Luigi
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p. 1149 - 1154
(2014/04/03)
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- Characterization of a new enzyme oxidizing ω-amino group of aminocarboxyric acid, aminoalcohols and amines from Phialemonium sp. AIU 274
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A new enzyme exhibiting oxidase activity for ω-aminocarboxylic acids, ω-aminoalcohols, monoamines and diamines was found from a newly isolated fungal strain, Phialemonium sp. AIU 274. The enzyme also oxidized aromatic amines, but not l- and d-amino acids. The Vmax/Km value for hexylamine was higher than those for 6-aminoalcohol and 6-aminhexanoic acid in the aliphatic C6 substrates. In the aliphatic amines, the higher Vmax/Km values were obtained by the longer carbon chain amines. Thus, the enzyme catalyzed oxidative deamination of the ω-amino group in a wide variety of the ω-amino compounds and preferred medium- and long-chain substrates. The oxidase with such broad substrate specificity was first reported here. The enzyme contained copper, and the enzyme activity was strongly inhibited by isoniazid, iproniazid and semicarbazide, but not by clorgyline and pargyline. The enzyme was composed of two identical subunits of 75 kDa.
- Isobe, Kimiyasu,Sasaki, Tomoko,Aigami, Yuusuke,Yamada, Miwa,Kishino, Shigenobu,Ogawa, Jun
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- Precise supramolecular control of selectivity in the Rh-catalyzed hydroformylation of terminal and internal alkenes
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In this study, we report a series of DIMPhos ligands L1-L3, bidentate phosphorus ligands equipped with an integral anion binding site (the DIM pocket). Coordination studies show that these ligands bind to a rhodium center in a bidentate fashion. Experiments under hydroformylation conditions confirm the formation of the mononuclear hydridobiscarbonyl rhodium complexes that are generally assumed to be active in hydroformylation. The metal complexes formed still strongly bind the anionic species in the binding site of the ligand, without affecting the metal coordination sphere. These bifunctional properties of DIMPhos are further demonstrated by the crystal structure of the rhodium complex with acetate anion bound in the binding site of the ligand. The catalytic studies demonstrate that substrate preorganization by binding in the DIM pocket of the ligand results in unprecedented selectivities in hydroformylation of terminal and internal alkenes functionalized with an anionic group. Remarkably, the selectivity controlling anionic group can be even 10 bonds away from the reactive double bond, demonstrating the potential of this supramolecular approach. Control experiments confirm the crucial role of the anion binding for the selectivity. DFT studies on the decisive intermediates reveal that the anion binding in the DIM pocket restricts the rotational freedom of the reactive double bound. As a consequence, the pathway to the undesired product is strongly hindered, whereas that for the desired product is lowered in energy. Detailed kinetic studies, together with the in situ spectroscopic measurements and isotope-labeling studies, support this mode of operation and reveal that these supramolecular systems follow enzymatic-type Michaelis-Menten kinetics, with competitive product inhibition.
- Dydio, Pawel,Detz, Remko J.,Reek, Joost N. H.
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supporting information
p. 10817 - 10828
(2013/08/23)
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- Remote supramolecular control of catalyst selectivity in the hydroformylation of alkenes
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In the pocket: The supramolecular interactions between a Rh phosphine catalyst equipped with an anion-binding pocket and alkenes that contain anionic functionalities (see picture) provide an excellent design concept to achieve remote control of the regioselectivity in hydroformylation reactions. The 4-pentenoate and 3-butenylphosphonate, which fit tightly between the Rh center and the pocket, were hydroformylated with unprecedented selectivity.
- Dydio, Pawea,Dzik, Wojciech I.,Lutz, Martin,De-Bruin, Bas,Reek, Joost N. H.
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supporting information; experimental part
p. 396 - 400
(2011/03/16)
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- Regioselective cyclization of alpha,omega-alkynoic acids catalysed by TpRu complexes: synthesis of endocyclic enol lactones [Tp = hydrotris(pyrazolyl)borate].
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The sigma-enynyl complex [TpRu(C(Ph)=C(Ph)C identical to CPh)(P-MeiPr2)] efficiently catalyses the regioselective cyclization of alpha,omega-alkynoic acids to yield endocyclic enol lactones having ring size up to 12 atoms.
- Jimenez-Tenorio,Puerta,Valerga,Moreno-Dorado,Guerra,Massanet
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p. 2324 - 2325
(2007/10/03)
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- Kinetics and Mechanism of Acid Bromate Oxidation of Aliphatic, Aralkyl and Alicyclic Ketones
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Oxidation of a few typical aliphatic, aralkyl and alicyclic ketones with acid bromate has been investigated.The reaction is first order in both and .The rate increases with increase in of the medium.Ionic strength effect is marginal but the oxidation rates are susceptible to change in dielectric constant of the medium.The mechanism proposed involves the attack of acid bromate on the enol-form of the ketone in the rate-determining, formation of an intermediate followed by a fast decomposition to products.The order of reactivities is: (i) ethyl methyl ketone > n-propyl methyl ketone > dimethyl ketone for simple aliphatic ketones; (ii) acetophenone > propiophenone > butyrophenone for aralkyl ketones; and (iii) cyclooctanone > cyclohexanone > cycloheptanone for alicyclic ketones.Thermodynamic parameters have been evaluated and discussed.
- Krishnamurthy, N.,Sanjeeva Reddy, Ch.,Sundaram, E. V.
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p. 288 - 291
(2007/10/02)
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