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Interaction of Ions in Organic and Aqueous Media with an Ion-Pair Sensor Equipped with a BODIPY Reporter: An ON1-OFF-ON2-ON3 Fluorescent Assay. Int J Mol Sci 2023; 24:ijms24108536. [PMID: 37239885 DOI: 10.3390/ijms24108536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 04/29/2023] [Accepted: 05/04/2023] [Indexed: 05/28/2023] Open
Abstract
Here, we present a ditopic ion-pair sensor, B1, containing the BODIPY reporter unit in its structure, which is shown to be able-thanks to the presence of two heterogeneous binding domains-to interact with anions in an enhanced manner in the presence of cations. This enables it to interact with salts even in 99% aqueous solutions, making B1 a good candidate in terms of visual salt detection in the aquatic environment. Receptor B1's ability to extract and release salt was applied in the transport of potassium chloride through a bulk liquid membrane. Working with a concentration of B1 in the organic phase and with the presence of a specific salt in an aqueous solution, an inverted transport experiment was also demonstrated. By varying the type and the amount of the anions added to B1, we were able to develop diverse optical responses, including a unique four-step ON1-OFF-ON2-ON3 output.
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2
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The use of microelectrodes to study ion recognition by a squaramide-based ion pair receptor consisting of a ferrocene reporter. J Electroanal Chem (Lausanne) 2022. [DOI: 10.1016/j.jelechem.2022.117058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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3
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Utilizing a polymer containing squaramide-based ion pair receptors for salt extraction. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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4
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Fluorescence Recognition of Anions Using a Heteroditopic Receptor: Homogenous and Two-Phase Sensing. Int J Mol Sci 2021; 22:13396. [PMID: 34948192 PMCID: PMC8703701 DOI: 10.3390/ijms222413396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022] Open
Abstract
In contrast to monotopic receptor 3, the anthracene functionalized squaramide dual-host receptor 1 is capable of selectively extracting sulfate salts, as was evidenced unambiguously by DOSY, mass spectrometry, fluorescent and ion chromatography measurements. The receptors were investigated in terms of anion and ion pair binding using the UV-vis and 1H NMR titrations method in acetonitrile. The reference anion receptor 3, lacking a crown ether unit, was found to lose the enhancement in anion binding induced by the presence of cations. Besides the ability to bind anions in an enhanced manner exhibited by ion pair receptors 2 and 4, changing the 1-aminoanthracene substituent resulted in their exhibiting a lower anion affinity than receptor 1. By using receptor 1 and adjusting the water content in organic phase it was possible to selectively detect sulfates both by "turn-off" and "turn-on" fluorescence, and to do so homogenously and under interfacial conditions. Such properties of receptor 1 have allowed the development of a new type of sensor capable of recognizing and extracting potassium sulfate from the aqueous medium across a phase boundary, resulting in an appropriate fluorescent response in the organic solution.
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5
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Tripodal, Squaramide-Based Ion Pair Receptor for Effective Extraction of Sulfate Salt. Molecules 2021; 26:2751. [PMID: 34067071 PMCID: PMC8125518 DOI: 10.3390/molecules26092751] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/01/2021] [Accepted: 05/05/2021] [Indexed: 11/20/2022] Open
Abstract
Combining three features-the high affinity of squaramides toward anions, cooperation in ion pair binding and preorganization of the binding domains in the tripodal platform-led to the effective receptor 2. The lack of at least one of these key elements in the structures of reference receptors 3 and 4 caused a lower affinity towards ion pairs. Receptor 2 was found to form an intramolecular network in wet chloroform, which changed into inorganic-organic associates after contact with ions and allowed salts to be extracted from an aqueous to an organic phase. The disparity in the binding mode of 2 with sulfates and with other monovalent anions led to the selective extraction of extremely hydrated sulfate anions in the presence of more lipophilic salts, thus overcoming the Hofmeister series.
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6
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Macrocyclic squaramides as ion pair receptors and fluorescent sensors selective towards sulfates. Dalton Trans 2021; 50:3904-3915. [PMID: 33635308 DOI: 10.1039/d0dt04273k] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Through the high dilution technique, we obtained macrocyclic ion pair receptors R1 and R2, an anion receptor R3, and a fluorescent sensor R4 using a combination of particular members of simple libraries consisting of synthesized diamines and methyl squarates, respectively. The receptors were investigated in terms of anion and ion pair binding using the 1H NMR titration method in DMSO-d6. We found that the major contribution to the anion binding comes from the interaction with the squaramide protons rather than with the amide functions of the receptors. The receptors demonstrated the highest affinity towards benzoates and sulfates over the anions tested, and in the case of sulfate binding more complex equilibria in solution were observed. Unlike the anion receptor R3, the ion pair receptor R1 was found to recognize anions in an enhanced manner with the assistance of sodium or potassium cations. Tethering of a simple fluorophore in close proximity to the amide function of receptor R4 resulted in an optical ion pair sensor selective towards sulfates. DFT calculations carried out for the 1 : 1 complexes of R3 with the anions helped clarify this selectivity, showing more effective participation of tetrahedral sulfate anions in binding with the amide function than in the case of benzoates or chlorides.
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7
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Cooperative Transport and Selective Extraction of Sulfates by a Squaramide-Based Ion Pair Receptor: A Case of Adaptable Selectivity. Inorg Chem 2020; 59:13749-13759. [PMID: 32885659 PMCID: PMC7509838 DOI: 10.1021/acs.inorgchem.0c02114] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Indexed: 11/30/2022]
Abstract
The use of a squaramide-based ion pair receptor offers a solution to the very challenging problem of extraction and transport of extremely hydrated sulfate salt. Herein we demonstrate for the first time that a neutral receptor is able not only to selectively extract but also to transport sulfates in the form of an alkali metal salt across membranes and to do so in a cooperative manner while overcoming the Hofmeister bias. This was made possible by an enhancement in anion binding promoted by cation assistance and by diversifying the stoichiometry of receptor complexes with sulfates and other ions. The existence of a peculiar 4:1 complex of receptor 2 with sulfates in solution was confirmed by UV-vis and 1H NMR titration experiments, DOSY and DLS measurements, and supported by solid-state X-ray measurements. By varying the separation technique and experimental conditions, it was possible to switch the depletion of the aqueous layer into extremely hydrophilic or less lipophilic salts, thus obtaining the desired selectivity.
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Abstract
Ferrocene offers a convenient reporter in squaramide based ion pair sensors able to recognize anions more strongly in the presence of cations.
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Ion-pair induced supramolecular assembly formation for selective extraction and sensing of potassium sulfate. Chem Sci 2019; 10:9542-9547. [PMID: 32055325 PMCID: PMC6979319 DOI: 10.1039/c9sc02923k] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
Selective extraction of sulfates in the form of alkali metal salts using charge-neutral molecular receptors is one of the holy grails of supramolecular chemistry. Herein we describe, for the first time, a squaramide-based ion pair receptor equipped with a crown ether site that is able to extract potassium sulfate from the aqueous to the organic phase (an analogous monotopic anion receptor lacking the crown ether unit lacks this ability). 1H NMR, UV-vis, DOSY-NMR, DLS, and MS experiments and the solid-state single crystal structure provided evidence of the formation of a supramolecular core-shell like assembly upon interaction of the receptor with potassium sulfate. The presence of monovalent potassium salts, in contrast, promoted the formation of simple 1 : 1 complexes. Unlike the 4 : 1 assembly, the 1 : 1 complexes are poorly soluble in organic media. This feature was utilized to overcome the Hofmeister bias and allow for selective extraction of extremely hydrophilic sulfates over lipophilic nitrate anions, which was unambiguously proved by quantitative AES and ion chromatography measurements. A simple modification of the receptor structure led to a "naked eye" optical sensor able to selectively detect sulfates under both SLE and LLE conditions.
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A Novel Strategy for the Synthesis of Amphiphilic and Thermoresponsive Poly(N-isopropylacrylamide)- b-Polystyrene Block Copolymers via ATRP. Polymers (Basel) 2019; 11:E1484. [PMID: 31514392 PMCID: PMC6780390 DOI: 10.3390/polym11091484] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/01/2019] [Accepted: 09/09/2019] [Indexed: 11/16/2022] Open
Abstract
A new synthetic approach is presented for the preparation of Poly(N-isopropylacrylamide-block-styrene) PNIPAM-b-PS via an Atom Transfer Radical Polymerization (ATRP) technique. The proposed method is based on application of 2-chloro-N-(2-hydroxyethyl)propanamide (NCPAE) as a bifunctional initiator, which enables ATRP of two monomers, differing in activity and polarity, into two stages. The synthesized copolymer molecules contain two well-defined polymer chains connected by a linker, which is a derivative of the proposed initiator. Using NCPAE led to PNIPAMs with well-planned molecular weight, low polydispersities (PDI=1.1÷1.3) and hydroxyl functionality. Activation of such blocks for initiation of styrene polymerization was performed using α-bromoisobutyryl bromide. After such a modification, the synthesized homopolymers acted as macroinitiators in ARGET ATRP and a well-defined polystyrene block, as the next one in the polymer chain was successfully formed. Both of the synthesized macromolecules, PNIPAM and PNIPAM-b-PS, exhibit a thermoresponsive behavior with explicit lower critical solution temperatures (LCST) in their aqueous solutions. The synthesized homopolymers and subsequently derived block copolymers were characterized using Size-Exclusion Chromatography, Differential Scanning Calorimetry, Dynamic Light Scattering, and NMR spectroscopy.
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The Effect of Substitution Pattern on Binding Ability in Regioisomeric Ion Pair Receptors Based on an Aminobenzoic Platform. Molecules 2019; 24:molecules24162990. [PMID: 31426565 PMCID: PMC6720599 DOI: 10.3390/molecules24162990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/12/2019] [Accepted: 08/14/2019] [Indexed: 12/30/2022] Open
Abstract
A series of ditopic ion pair receptors equipped with 4-nitrophenylurea and 1-aza-18-crown-6-ether linked by ortho-(1), meta-(2), and para-(3) substituted benzoic acid were readily synthesized in three steps from commercially available materials. The binding properties of these regioisomeric receptors were determined using UV-vis and 1H NMR spectroscopy in MeCN and in the solid state by single-crystal X-ray diffraction crystallography. The solution studies revealed that, apart from carboxylates, all the anions tested formed stronger complexes in the presence of sodium cations. Receptors 2 and 3 were found to interact with ion pairs with remarkably higher affinity than ortho-substituted 1. 1H NMR titration experiments showed that both urea NH protons interacted with anions with comparable strength in the case of receptors 2 and 3, but only one of the NHs was effective in anion binding in the case of receptor 1. X-ray analysis of the crystal structure of receptor 1 and 1·NaPF6 complex showed that binding was hampered due to the formation of an intramolecular hydrogen bond. Analysis of the crystal structures of 2·NaBr and 3·NaBr complexes revealed that proper mutual orientation of binding domains was responsible for the improved binding of the sodium salts.
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13
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Abstract
We synthesized an ion pair receptor 1 consisting of a crown ether cation binding site and a squaramide anion binding domain and compared its binding properties to those of its analogous urea counterpart 2. We studied their salt binding properties using spectrophotometric and spectroscopic measurements in an acetonitrile solution and in acetonitrile/water mixtures. Apart from carboxylate anions, all of the anions tested were found to associate with receptor 1 and 2 more strongly in the presence of sodium cations. A homotopic anion receptor 3, lacking a crown ether unit, was unable to bind sodium salt more strongly than tetrabutylammonium salts. Solution and solid-state X-ray measurements revealed strong sodium chloride coordination to receptor 1, which is able to bind this salt even in the presence of 10% water. In contrast to the urea-based ion pair receptor 2 or anion receptor 3, ditopic receptor 1 is capable of extracting sodium chloride from aqueous media to the organic phase, as was evidenced unambiguously by 1H nuclear magnetic resonance, mass spectrometry, and atomic absorption spectroscopy analyses.
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Sodium thiocyanate binding by a 3-aminobenzoic acid based ion pair receptor consisting of a thiourea binding domain. INORG CHEM COMMUN 2017. [DOI: 10.1016/j.inoche.2017.08.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Enantioselective recognition of sodium carboxylates by an 1,8-diaminoanthracene based ion pair receptor containing amino acid units. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.07.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Cooperative binding and extraction of sodium nitrite by a ditopic receptor incorporated into a polymeric resin. Dalton Trans 2016; 45:11639-43. [PMID: 27373908 DOI: 10.1039/c6dt02235a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Simple ion pair receptors were synthesised and characterized in solution. The modular design of these receptors facilitated the preparation of a functionally analogous polymeric material able to extract sodium nitrite from acetonitrile solution.
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18
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An ion pair receptor facilitating the extraction of chloride salt from the aqueous to the organic phase. NEW J CHEM 2016. [DOI: 10.1039/c6nj01482h] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A squaramide supported molecular receptor with the ability to extract chloride salt from the aqueous to the organic phase was synthesized and characterized.
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19
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Abstract
The development of l-ornithine based multitopic receptors allowed us to obtain an effective and selective salt receptor.
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20
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Abstract
A polymerizable molecular receptor able to bind ion pairs and new functional polymers containing the receptor units were synthesized and characterized.
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21
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Boosting the salt recognition abilities of l-ornithine based multitopic molecular receptors by harnessing a double cooperative effect. Dalton Trans 2014; 43:8515-22. [DOI: 10.1039/c4dt00576g] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Systematic development of the geometric and electronic properties of the amino acid based salt receptors leads to a very effective and selective NaNO2 receptor.
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22
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Selective ammonium nitrate recognition by a heteroditopic macrotricyclic ion-pair receptor. J Org Chem 2013; 78:4341-7. [PMID: 23560870 DOI: 10.1021/jo4003322] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The heteroditopic macrotricyclic molecular receptor 1, which bears a tripodal anion binding domain and 4,10,16-triaza-18-crown-6 cation recognition domain, proves to be an effective ion-pair receptor. In the absence of the cobound cation (TBA(+) salts) receptor 1 preferably binds nitrate and nitrite over other anions, including basic anions such as acetate or dihydrogenphosphate. Ammonium cation binding by the 4,10,16-triaza-18-crown-6 subunit significantly enhances the strength of the nitrate and nitrite complexation at the triamide recognition site of the receptor. In the presence of ammonium cations, the association constants of nitrate binding reach an impressive value of 1050 M(-1) in highly polar DMSO-d6. Interestingly, the binding of other anions such as chloride and bromide is not enhanced in the presence of a cobound NH4(+) cation. The increased affinity of [1·NH4(+)]PF6(-) for anionic species is attributed to a strong cooperative effect that arises from the properly positioned binding sites in the receptor 1 cavity, thus allowing for the formation of the ion pair. Under liquid/liquid conditions, receptor 1 is able to extract NH4NO3 from an aqueous to an organic phase, as inferred from (1)H NMR spectroscopic and nitrite/nitrate colorimetric analyses.
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Selective NaNO2 recognition by a simple heteroditopic salt receptor based on l-ornithine molecular scaffold. Dalton Trans 2013; 42:15271-4. [DOI: 10.1039/c3dt52311j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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24
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Oxidation of ferrocenemethanol grafted to a hydrogel network through cysteine for triggering volume phase transition. RSC Adv 2013. [DOI: 10.1039/c3ra42405g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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25
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Diastereoselective 1,3-Dipolar Cycloadditions of Chiral Derivatives of 2-Oxoethanenitrile Oxide to Noncyclic Conjugated Symmetrical Alkenes. Helv Chim Acta 2007. [DOI: 10.1002/hlca.200790219] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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26
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Asymmetric 1,3-dipolar cycloadditions of chiral carboxyloyl nitrile oxides to cycloalkenes. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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27
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The synthesis of oximes and nitroalkanes bearing a chiral auxiliary unit: convenient substrates for the preparation of enantiomerically pure nitrile oxides. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.tetasy.2005.05.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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