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Artículos de revistas sobre el tema "Aldimine ligands"

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Publicado: 18 de mayo de 2024

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1

Brewer, Greg, Cynthia Brewer, Raymond J. Butcher y Peter Zavalij. "Formation of Ketimines from Aldimines in Schiff Base Condensation of Amino Acids and Imidazole-2-Carboxaldehydes: Tautomerization of Schiff Bases of Amino Acids Resulting in the Loss of Stereogenic Center". Inorganics 11, n.º 10 (25 de septiembre de 2023): 381. http://dx.doi.org/10.3390/inorganics11100381.

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The Schiff base reaction of imidazole-2-carboxaldehydes with the anion of alanine, leucine and phenylalanine in the presence of nickel(II) ion gives the neutral NiL2 complexes. The Schiff base ligand, L, binds through an imidazole nitrogen, NIm, the amino acid nitrogen, NAA, and a carboxylate oxygen, O, atom. The two N2O ligands bind to the nickel(II) in a meridional fashion with the NIm and O of each ligand in trans positions. These ligands can exist as the anticipated aldimine, Im − CH = NAA − CH(R) − CO2−, or the ketimine, Im − CH2NAA = C(R) − CO2−, tautomer. Tautomerization of the initially formed aldimine Schiff base results in movement of the hydrogen atom of the alpha carbon of the amino acid to the aldehyde carbon, CAld, atom of the imidazole carboxaldehyde with resultant relocation of the imine double bond in the reverse direction. Ten structures of the structurally unprecedented ketimine tautomer, prepared from imidazole-2-carboxaldehydes and a pyrazole-3-carboxaldehyde, were presented. The structural data supported the formation of the ketimines in each case, while the aldimine tautomer was observed with imidazole-4-carboxaldehydes. A rationale of this can be explained on the basis of charge distribution in the likely intermediate in the tautomerization.
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2

Hanessian, Stephen, Eric Jnoff, Noemy Bernstein y Michel Simard. "Bifunctional bis(oxazolines) as potential ligands in catalytic asymmetric reactions". Canadian Journal of Chemistry 82, n.º 2 (1 de febrero de 2004): 306–13. http://dx.doi.org/10.1139/v03-198.

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C2-symmetrical bis(oxazoline) ligands bearing pendant alkylthio ether groups were synthesized, and the structures of Cu complexes were determined by single crystal X-ray diffraction. The potential utility in catalysis was shown in the asymmetric addition of methyllithium to an aromatic aldimine, which resulted in a mixture of products with an enantiomeric excess of 68%.Key words: two-center catalysis, bis(oxazoline), aldimine, imine alkylation.
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3

ALI, Uzma, Aneela MAALIK, Muhammad Babar TAJ, Ahmad RAHEEL, Ahmad Kaleem QURESHI, Muhammad IMRAN, Muhammad SHARIF, Syed Ahmad TIRMIZI, Sadia NOOR y Heba ALSHATER. "Facile synthesis, solublization studies and anti-inflammatory activity of amorphous zinc(II) centered aldimine complexes". Revue Roumaine de Chimie 65, n.º 10 (2021): 929–41. http://dx.doi.org/10.33224/rrch.2020.65.10.08.

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In this study, Zn(II) centered complexes with aldimine derivatives were synthesized using green solvent, polyethylene glycol (PEG-400) and amorphous complexes were characterized by FT-IR, multinuclear (1H and 13C NMR), elemental and thermal analysis. Thermogravimetric analysis indicated the extended thermal stability of the synthesized complexes. All the Zn(II) complexes show very significant photoexcitation in the range of 318 – 384 nm and photoemission in the range of 502 – 562 nm. Among all the complexes, Zn(II) complex (3Zn) showed minimum band gap value, 2.35 eV. These amorphous complexes have been reported for their wide applications in biomedical sciences. The synthesized aldimine ligands and Zn(II) complexes were investigated for anti-inflammatory activity and these complexes showed more anti-inflammatory potential than the corresponding aldimine ligands. The solubilization of zinc complexes in sodium dodecyl sulphate was also investigated to reveal the interaction of metal complexes by using UV-Visible spectroscopy and electrical conductivity measurements.
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4

Dutta, Jayita, Michael G. Richmond y Samaresh Bhattacharya. "Palladium(0)-mediated C–H bond activation of N-(naphthyl)salicylaldimine and related ligands: utilization of the resulting organopalladium complexes in catalytic C–C and C–N coupling reactions". Dalton Transactions 44, n.º 30 (2015): 13615–32. http://dx.doi.org/10.1039/c5dt01564b.

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5

Wu, Rui, Ruslan Sanishvili, Boris R. Belitsky, Jose I. Juncosa, Hoang V. Le, Helaina J. S. Lehrer, Michael Farley et al. "PLP and GABA trigger GabR-mediated transcription regulation in Bacillus subtilis via external aldimine formation". Proceedings of the National Academy of Sciences 114, n.º 15 (27 de marzo de 2017): 3891–96. http://dx.doi.org/10.1073/pnas.1703019114.

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The Bacillus subtilis protein regulator of the gabTD operon and its own gene (GabR) is a transcriptional activator that regulates transcription of γ-aminobutyric acid aminotransferase (GABA-AT; GabT) upon interactions with pyridoxal-5′-phosphate (PLP) and GABA, and thereby promotes the biosynthesis of glutamate from GABA. We show here that the external aldimine formed between PLP and GABA is apparently responsible for triggering the GabR-mediated transcription activation. Details of the “active site” in the structure of the GabR effector-binding/oligomerization (Eb/O) domain suggest that binding a monocarboxylic γ-amino acid such as GABA should be preferred over dicarboxylic acid ligands. A reactive GABA analog, (S)-4-amino-5-fluoropentanoic acid (AFPA), was used as a molecular probe to examine the reactivity of PLP in both GabR and a homologous aspartate aminotransferase (Asp-AT) from Escherichia coli as a control. A comparison between the structures of the Eb/O–PLP–AFPA complex and Asp-AT–PLP–AFPA complex revealed that GabR is incapable of facilitating further steps of the transamination reaction after the formation of the external aldimine. Results of in vitro and in vivo assays using full-length GabR support the conclusion that AFPA is an agonistic ligand capable of triggering GabR-mediated transcription activation via formation of an external aldimine with PLP.
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6

Taj, Muhammad Babar, Muneera D. F. Alkahtani, Uzma Ali, Ahmad Raheel, Walla Alelwani, Afnan M. Alnajeebi, Nouf Abubakr Babteen, Sadia Noor y Heba Alshater. "New Heteroleptic 3D Metal Complexes: Synthesis, Antimicrobial and Solubilization Parameters". Molecules 25, n.º 18 (16 de septiembre de 2020): 4252. http://dx.doi.org/10.3390/molecules25184252.

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The microbial resistance to current antibiotics is increasing day by day, which in turn accelerating the development of new effective drugs. Several studies have proved the high antimicrobial potential of the interaction of several organic ligands with a variety of metal ions. In the present study, a conventional method has been adopted in the synthesis of twelve new heteroleptic complexes of cobalt (II), nickel (II), copper (II) and zinc (II) using three aldimines, namely, (HL1 ((E)-2-((4-chloro-2-hydroxybenzylidene)amino)-3,4-dimethyl-5-phenylcyclopent-2-en-1-one), HL2 ((Z)-3-((4-chlorobenzylidene)amino)-4-hydroxy-5-nitrobenzenesulfonic acid) HL3 (2,2′-((1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))diphenol)) as primary ligands, while phenyl glycine was the secondary ligand. The synthesized compounds were characterized by UV-vis, IR and multinuclear (1H and 13C) NMR spectroscopy, elemental analysis, and electrical conductance. The IR study revealed the coordination of the aldimine derivatives with the -OH and N atom of imine moiety. In contrary to this, the phenyl glycine coordinated to the metal ions via oxygen of carboxylate and nitrogen of the amino group. The spectroscopic analysis unveiled the tetrahedral geometry of the synthesized metal (II) complexes, except for ligand HL3 which exhibited octahedral geometry. The synthesized compounds generally showed antibacterial activity for all microbes, except Ni (II) complexes lacking sensitivity. Furthermore, to access the bioavailability, the synthesized complexes were screened for their solubilization in the micellar media of sodium lauryl sulphate. The metal complex–surfactant interaction was revealed by UV-vis spectroscopy and electrical conductivity measurements.
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7

Rath, Sankar P., Sujit Mondal y Tapas Ghosh. "Mixed-ligand oxovanadium(V) complexes incorporating bidentate salicylaldehyde and tridentate aldimine ligands". Transition Metal Chemistry 21, n.º 4 (agosto de 1996): 309–11. http://dx.doi.org/10.1007/bf00139024.

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8

Wosińska-Hrydczuk, Marzena y Jacek Skarżewski. "New Nitrogen, Sulfur-, and Selenium-Donating Ligands Derived from Chiral Pyridine Amino Alcohols. Synthesis and Catalytic Activity in Asymmetric Allylic Alkylation". Molecules 26, n.º 12 (8 de junio de 2021): 3493. http://dx.doi.org/10.3390/molecules26123493.

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Although many chiral ligands for asymmetric catalysis have been developed, there is still a need for new structures allowing the modular approach. Recently, easy synthesis of chiral pyridine-containing β-amino alcohols has been elaborated by opening respective epoxides with enantiomeric 1-phenylethylamine. This paper reports the synthetic transformation of β-amino alcohols into the new complexing pyridine-containing seleno- and thioethers. The amino alcohols were effectively converted to cyclic sulfonamidates, which were reacted with thiolates or phenyl selenide nucleophile. The reaction was diastereoselective, and its outcome depended on the configuration at the substitution center. The problem was discussed considering DFT optimized structures of both diastereomeric sulfonamidates. New amino-aldimine ligands were also synthesized from chiral pyridine-containing diamines. Nine new chiral ligands were tested in the Tsuji-Trost allylic alkylation resulting in the enantiomerically enriched product in up to 75% ee. The observed stereochemical induction agrees with the prevailing nucleophilic attack at the allylic carbon laying opposite to the complexing nitrogen of pyridine in η3-allylic intermediate complexes.
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9

Zhou, Xiaoyu, Jiaxin Yang, Zhiqiang Hao, Zhangang Han, Jin Lin y Guo-Liang Lu. "Copper Complexes with N,N,N-Tridentate Quinolinyl Anilido-Imine Ligands: Synthesis and Their Catalytic Application in Chan−Lam Reactions". Molecules 28, n.º 21 (3 de noviembre de 2023): 7406. http://dx.doi.org/10.3390/molecules28217406.

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The treatment of 2-(ArNC(H))C6H4-HNC9H6N with n-BuLi and the subsequent addition of CuCl2 afforded the anilido-aldimine Cu(II) complexes 1-5 Cu[{2-[ArN=C(H)]C6H4}N(8-C9H6N)]Cl (Ar = 2,6-iPr2C6H3 (1), 2,4,6-(CH3)3C6H2 (2), 4-OCH3C6H4 (3), 4-BrC6H4 (4), 4-ClC6H4 (5)), respectively. All the copper complexes were fully characterized by IR, EPR and HR-MS spectra. The X-ray diffraction analysis reveals that 2 and 4 are mononuclear complexes, and the Cu atom is sitting in a slightly square-planar geometry. These Cu(II) complexes have exhibited excellent catalytic activity in the Chan–Lam coupling reactions of benzimidazole derivatives with arylboronic acids, achieving the highest yields of up to 96%.
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10

Agarwal, Ram K. y Surendra Prasad. "Synthesis, Spectroscopic and Physicochemical Characterization and Biological Activity of Co(II) and Ni(II) Coordination Compounds with 4-Aminoantipyrine Thiosemicarbazone". Bioinorganic Chemistry and Applications 3, n.º 3-4 (2005): 271–88. http://dx.doi.org/10.1155/bca.2005.271.

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We describe the synthesis and characterization of cobalt(II) and nickel(II) coordination compounds of 4[N-(furan-2’-aldimine)amino]antipyrine thiosemicarbazone (FFAAPTS) and 4[N-(4'-nitrobenzalidene) amino]antipyrine thiosemicarbazone (4'-NO2BAAPTS). All the isolated compounds have the general composition MX2(L)(H2O) (M = Co2+or Ni2+; X = Cl, Br, NO3, NCS or CH3COO; L = FFAAPTS or 4'-NO2BAAPTS) and M(ClO4)2(L)2(M = Co2+or Ni2+; L = FFAAPTS or 4'-NO2BAAPTS). Infrared spectral studies indicate that both the thiosemicarbazones coordinate in their neutral form and they act as {N,N,S} tridentate chelating ligands. Room temperature magnetic measurements and electronic spectral studies suggest the distorted octahedral geometries of the prepared complexes. Thermogravimetric studies are also reported and the possible structures of the complexes are proposed. Antibacterial and antifungal properties of these metal-coordination compounds have also been studied.
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11

Chen, Chi-Tien, Min-Chian Wang y Tzu-Lun Huang. "Zinc Complexes Containing Coumarin-Derived Anilido-Aldimine Ligands as Catalysts for Ring Opening Polymerization of L-Lactide". Molecules 20, n.º 4 (24 de marzo de 2015): 5313–28. http://dx.doi.org/10.3390/molecules20045313.

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12

Doyle, David J., Vernon C. Gibson y Andrew J. P. White. "Synthesis and structures of bimetallic and polymeric zinc coordination compounds supported by salicylaldiminato and anilido–aldimine ligands". Dalton Trans., n.º 3 (2007): 358–63. http://dx.doi.org/10.1039/b615080b.

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13

Panchana, Subrata y Parag S. Roy. "Effect of conformational factors on metal- and ligand-centred electron transfer processes of coordination compounds of aldimine ligands derived from L-/D-amino acids". Proceedings / Indian Academy of Sciences 106, n.º 3 (junio de 1994): 772. http://dx.doi.org/10.1007/bf02911122.

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14

Rajendran, Uma y Mallayan Palaniandavar. "Models for blue copper proteins: Copper(II)-disulfide interaction in some copper complexes containing salicyl-, pyridyl-, and imidazolyl-aldimine ligands." Journal of Inorganic Biochemistry 43, n.º 2-3 (agosto de 1991): 212. http://dx.doi.org/10.1016/0162-0134(91)84204-m.

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15

Böttcher, Arnd, Horst Elias, Brigitte Eisenmann, Elke Hilms, Andreas Huber, Rüdiger Kniep, Caroline Röhr, Margareta Zehnder, Markus Neuburger y Johan Springborg. "A Novel Synthetic Approach to Asymmetric Salen, Dihydrosalen, and Tetrahydrosalen Ligands: Structures and O2-Activating Properties of their Nickel(II) and Cobalt(II) Complexes". Zeitschrift für Naturforschung B 49, n.º 8 (1 de agosto de 1994): 1089–100. http://dx.doi.org/10.1515/znb-1994-0814.

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A synthetic procedure is described for the preparation of the tetradentate N2O2 ligands H2[H4]L1=6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methyl- phenyl)heptane, H2[H2]L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2-hydroxy-3-t-butyl-5-methylphenyl)-1-heptene, and H2L1 = 6-(2-hydroxyphenyl)-2,5-diaza-3,3-dimethyl-1-(2- hydroxy-3-t-butyl-5-methylphenyl)-1,5-heptadiene, which are asymmetric derivatives of the ligands tetrahydrosalen, dihydrosalen, and salen. Complexes Ni[H4]L1, Ni[H2]L1, NiL1, CoL1, Ni[H4]L2 (([H4]L2)2- = anion of H2[H4]L2 = N,N'-bis(2-hydroxy-3-t-butyl-5-methylbenzyl)- trans-(S,S)-1,2-diaminocyclohexane), and NiL2 were prepared, characterized (VIS and IR ab­sorption, magnetic moment) and subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. Single crystal X-ray structure analy­ses were carried out for Ni[H2]L1 (monoclinic, P21/n; a = 8.926(4), b = 29.324(7), c = 8.411(4) Å; β = 95.3(1)°; Z = 4), CoL1 (monoclinic, C2/c; a = 25.389(2), b = 18.139(2), c = 10.179(1) Å; β = 112.227(6); Z = 8), and Ni[H4]L2·acetone (tetragonal, P41212; a = 13.928(3), c = 33.698(5) Å; Z = 8). In all of the three complexes, the N2O2-metal coordination core is square-planar. The skeleton of the tetradentate ligand is more or less twisted. The planar cobalt(II) complex CoL1 is a low spin d7 system with μexp = 2.02 BM at 298 K, whereas the planar complexes NiL1, Ni[H2]L1 and Ni[H4]L2 are diamagnetic (μexp = 0.28-0.64 BM). The blue solvate Ni[H4]L1- 3EtOH · H2O is paramagnetic (μexp = 3.04 BM), which points to octahedral coordination. In aerated acetone solution, the tetrahydrosalen-type complex Ni[H4]L1 activates dioxygen and one C-N bond is oxidatively dehydrogenated. The VIS spectrum of the dihydrosalen-type complex formed is virtually identical with that of the aldimine complex Ni[H2]L1. In the pres­ence of dioxygen, Co[H4]L1 and Co[H2]L1 are readily oxidized to CoL1 in acetone solution.
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16

Hu, Xiangping, Huilin Chen, Huicong Dai y Zhuo Zheng. "Synthesis of novel P-ketimine bidentate ferrocenyl ligands with central and planar chirality and comparsion in the catalytic activity between P-ketimine and P-aldimine". Tetrahedron: Asymmetry 14, n.º 21 (octubre de 2003): 3415–21. http://dx.doi.org/10.1016/j.tetasy.2003.09.034.

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17

Deshmukh, Ashish y Balasubramanian Gopal. "Structural insights into the catalytic mechanism of Bacillus subtilis BacF". Acta Crystallographica Section F Structural Biology Communications 76, n.º 3 (1 de marzo de 2020): 145–51. http://dx.doi.org/10.1107/s2053230x20001636.

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The nonribosomal biosynthesis of the dipeptide antibiotic bacilysin is achieved by the concerted action of multiple enzymes in the Bacillus subtilis bac operon. BacF (YwfG), encoded by the bacF gene, is a fold type I pyridoxal 5-phosphate (PLP)-dependent stereospecific transaminase. Activity assays with L-phenylalanine and 4-hydroxyphenylpyruvic acid (4HPP), a chemical analogue of tetrahydrohydroxyphenylpyruvic acid (H4HPP), revealed stereospecific substrate preferences, a finding that was consistent with previous reports on the role of this enzyme in bacilysin synthesis. The crystal structure of this dimeric enzyme was determined in its apo form as well as in substrate-bound and product-bound conformations. Two ligand-bound structures were determined by soaking BacF crystals with substrates (L-phenylalanine and 4-hydroxyphenylpyruvate). These structures reveal multiple catalytic steps: the internal aldimine with PLP and two external aldimine conformations that show the rearrangement of the external aldimine to generate product (L-tyrosine). Together, these structural snapshots provide an insight into the catalytic mechanism of this transaminase.
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18

Reed, Blake R., Sebastian A. Stoian, Richard L. Lord y Stanislav Groysman. "The aldimine effect in bis(imino)pyridine complexes: non-planar nickel(i) complexes of a bis(aldimino)pyridine ligand". Chemical Communications 51, n.º 30 (2015): 6496–99. http://dx.doi.org/10.1039/c5cc00203f.

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19

Kotwal, Dinkar P. "Synthesis, Characterization and Antimicrobial Study of Some Transition Metal Complexes with Aldimine". International Journal for Research in Applied Science and Engineering Technology 11, n.º 12 (31 de diciembre de 2023): 2284–87. http://dx.doi.org/10.22214/ijraset.2023.57829.

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Abstract: Aldimine ligand 2-Hydroxy-4,5- diiodo-benzylidene-4-hydroxy-aniline (L) and its complexes with Cu (II), Ni (II), Co (II) and Zn (II) were prepared and characterized by analytical, spectroscopic (IR, UV-Vis) techniques, thermal study, electrical conductivity and magnetic measurements. The results indicate that the ligand coordinate through azomithine nitrogen and oxygen of enolic group. The complexes were further screened for antimicrobial activity.
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20

Cabrera, Silvia, Olga García Mancheño, Ramón Gómez Arrayás, Inés Alonso, Pablo Mauleón y Juan C. Carretero. "Sulfenylphosphinoferrocenes: Novel planar chiral ligands in enantioselective catalysis". Pure and Applied Chemistry 78, n.º 2 (1 de enero de 2006): 257–65. http://dx.doi.org/10.1351/pac200678020257.

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Structurally well-defined transition-metal complexes of 1-phosphino-2-sulfenylferrocene (Fesulphos ligands) act as highly efficient catalysts in a variety of mechanistically different transformations. Excellent enantioselectivities were achieved in Pd-catalyzed allylic substitutions, desymmetrization of meso-heterobicyclic alkenes by Pd-catalyzed addition of dialkylzinc reagents, Pd-catalyzed Diels-Alder reaction of cyclopentadiene with N-acryloyl oxazolidinones, and in Cu-catalyzed formal aza-Diels-Alder reaction of Danishefsky diene to N-sulfonyl aldimines.
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21

Xue, Feng, Qibin Liu, Boshun Wan, Yong Zhu, Yifei Huang y Jimeng Ge. "Highly Enantioselective Rh-Catalyzed Arylation of N,N-Dimethylsulfamoyl-Protected Aldimines and Cyclic N-Sulfonylimines with Chiral Phenyl Backbone Sulfoxide-Olefin Ligands". Synthesis 52, n.º 10 (10 de febrero de 2020): 1498–511. http://dx.doi.org/10.1055/s-0037-1610749.

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With chiral 2-methoxy-1-naphthylsulfinyl-based phenyl backbone sulfoxide-olefin ligands, a highly Rh-catalyzed addition of aryl­boronic acids to N,N-dimethylsulfamoyl-protected aldimines has been developed to afford a broad range of chiral diarylmethylamines in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). Moreover, efficient enantioselective arylation of cyclic N-sulfonylimines was also achieved with excellent enantioselectivities (up to 98% ee).
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22

Machida, Yasuhiro, Takeshi Murakawa, Akiko Sakai, Mitsuo Shoji, Yasuteru Shigeta y Hideyuki Hayashi. "Reaction of threonine synthase with the substrate analogue 2-amino-5-phosphonopentanoate: implications into the proton transfer at the active site". Journal of Biochemistry 167, n.º 4 (13 de noviembre de 2019): 357–64. http://dx.doi.org/10.1093/jb/mvz100.

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Abstract Threonine synthase catalyses the conversion of O-phospho-l-homoserine and a water molecule to l-threonine and has the most complex catalytic mechanism among the pyridoxal 5′-phosphate-dependent enzymes. In order to study the less-characterized earlier stage of the catalytic reaction, we studied the reaction of threonine synthase with 2-amino-5-phosphonopentanoate, which stops the catalytic reaction at the enamine intermediate. The global kinetic analysis of the triphasic spectral changes showed that, in addition to the theoretically expected pathway, the carbanion is rapidly reprotonated at Cα to form an aldimine distinct from the external aldimine directly formed from the Michaelis complex. The Kd for the binding of inhibitor to the enzyme decreased with increasing pH, showing that the 2-amino-group-unprotonated form of the ligand binds to the enzyme. On the other hand, the rate constants for the proton migration steps within the active site are independent of the solvent pH, indicating that protons are shared by the active dissociative groups and are not exchanged with the solvent during the course of catalysis. This gives an insight into the role of the phosphate group of the substrate, which may increase the basicity of the ε-amino group of the catalytic lysine residue in the active site.
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23

Bailey, Philip J., Anna Collins, Peter Haack, Simon Parsons, Mahmudur Rahman, Damian Smith y Fraser J. White. "Palladium complexes of 6-aminofulvene-2-aldiminate (AFA) ligands". Dalton Trans. 39, n.º 6 (2010): 1591–97. http://dx.doi.org/10.1039/b914707a.

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Bailey, Philip J., Mahmudur Rahman, Simon Parsons, Muhammad R. Azhar y Fraser J. White. "Metalloligands containing aminofulvene-aldiminate (AFA) ligands and their bimetallic complexes". Dalton Transactions 42, n.º 8 (2013): 2879. http://dx.doi.org/10.1039/c2dt32804f.

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25

Deka, Geeta, Shveta Bisht, H. S. Savithri y M. R. N. Murthy. "Structural studies on the catalytic mechanism of Diaminopropionate ammonia lyase". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C1822. http://dx.doi.org/10.1107/s2053273314081789.

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Diaminopropionate ammonia lyase (DAPAL) is a non-stereo specific fold-type II pyridoxal 5' phosphate (PLP) dependent enzyme that catalyzes the conversion of both D/L isoforms of the nonstandard amino acid Diaminopropionate (DAP) to pyruvate and ammonia. DAP is important for the synthesis of nonribosomal peptide antibiotics such as viomycin and capreomycin. Earlier structural studies on EcDAPAL bound to a reaction intermediate (aminoacrylate) suggested that the enzyme follows a two base mechanism, where Asp120 and Lys77 function as general bases to abstract proton from D-DAP and L-DAP respectively. A novel disulfide was observed near the active site, although its functional significance was not clear. In the present study, structural and biochemical characterization of active site mutants Asp120 (Asp120Asn/Ser/Thr/Cys) and Lys77 (Lys77His/ Thr/Ala/Val) of EcDAPAL has been carried out. Reduction of catalytic efficiency (Kcat/Km) of D120N EcDAPAL for D-DAP by 140 fold and presence of the uncatalyzed ligand at the active site in the crystal structure suggested that Asp120 indeed abstracts proton from D-DAP. Lys77, which was speculated to be important for proton abstraction from L DAP, however seemed to be crucial for PLP binding only. Presence of non-covalently bound PLP in the L77W mutant and occurence of both the ketoenamine, enolimine forms of internal aldimine in L77R mutant provided an in depth insight into the unique chemistry of internal aldimine formation in PLP dependent enzymes. To investigate the role of the novel disulfide bond near the active site, C265 and C291 were mutated to Serine. Studies on these mutants show that this disulfide bond gives additional stability to the protein and might regulate the entry of substrates to the active site. Thus, these studies provide deeper insights into the reaction mechanism of EcDAPAL, representing the overall reaction mechanism followed by several other fold-type II PLP pendent enzymes.
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26

Inoue, Isao, Mitsuru Shindo, Kenji Koga y Kiyoshi Tomioka. "Asymmetric 1,2-addition of organolithiums to aldimines catalyzed by chiral ligand". Tetrahedron 50, n.º 15 (abril de 1994): 4429–38. http://dx.doi.org/10.1016/s0040-4020(01)89376-5.

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27

Znovjyak, Kateryna, Maksym Seredyuk, Sergey O. Malinkin, Sergiu Shova y Lutfullo Soliev. "Crystal structure of {N 1,N 3-bis[(1-benzyl-1H-1,2,3-triazol-4-yl)methylidene]-2,2-dimethylpropane-1,3-diamine}bis(thiocyanato-κN)iron(II)". Acta Crystallographica Section E Crystallographic Communications 76, n.º 10 (22 de septiembre de 2020): 1661–64. http://dx.doi.org/10.1107/s2056989020012608.

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The unit cell of the title compound, [FeII(NCS)2(C25H28N8)], consists of two charge-neutral complex molecules related by an inversion centre. In the complex molecule, the tetradentate ligand N 1,N 3-bis[(1-benzyl-1H-1,2,3-triazol-4-yl)methylene]-2,2-dimethylpropane-1,3-diamine coordinates to the FeII ion through the N atoms of the 1,2,3-triazole moieties and aldimine groups. Two thiocyanate anions, coordinating through their N atoms, complete the coordination sphere of the central ion. In the crystal, neighbouring molecules are linked through weak C—H...π, C—H...S and C—H...N interactions into a two-dimensional network extending parallel to (011). The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H...H (35.2%), H...C/C...H (26.4%), H...S/S...H (19.3%) and H...N/N...H (13.9%).
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28

Znovjyak, Kateryna, Maksym Seredyuk, Sergey O. Malinkin, Iryna A. Golenya, Tatiana Y. Sliva, Sergiu Shova y Nurullo U. Mulloev. "Crystal structure of (N 1,N 3-bis{[1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-yl]methylidene}-2,2-dimethylpropane-1,3-diamine)bis(thiocyanato)iron(II)". Acta Crystallographica Section E Crystallographic Communications 77, n.º 5 (9 de abril de 2021): 495–99. http://dx.doi.org/10.1107/s2056989021003662.

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The unit cell of the title compound, [FeII(NCS)2(C29H32N8O2)], consists of eight charge-neutral complex molecules. In the complex molecule, the tetradentate ligand N 1,N 3-bis{[1-(4-methoxybenzyl)-1H-1,2,3-triazol-4-yl]methylene}-2,2-dimethylpropane-1,3-diamine coordinates to the FeII ion through the N atoms of the 1,2,3-triazole and aldimine groups. Two thiocyanate anions, coordinated through their N atoms, complete the coordination sphere of the central Fe ion. In the crystal, neighbouring molecules are linked through weak C...C, C...N and C...S interactions into a one-dimensional chain running parallel to [010]. The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H...H (37.5%), H...C/C...H (24.7%), H...S/S...H (15.7%) and H...N/N...H (11.7%). The average Fe—N bond distance is 2.167 Å, indicating the high-spin state of the FeII ion, which does not change upon cooling, as demonstrated by low-temperature magnetic susceptibility measurements.
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29

Nakamura, Masaharu, Atsushi Hirai y Eiichi Nakamura. "Enantioselective Allylzincation of Cyclic Aldimines in the Presence of Anionic Bis-oxazoline Ligand". Journal of the American Chemical Society 118, n.º 35 (enero de 1996): 8489–90. http://dx.doi.org/10.1021/ja961213k.

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30

Deng, Hong-Ping, Yin Wei y Min Shi. "Axially Chiral Phosphine-Oxazoline Ligands in Silver(I)- Catalyzed Asymmetric Mannich Reaction of Aldimines with Trimethylsiloxyfuran". Advanced Synthesis & Catalysis 351, n.º 17 (noviembre de 2009): 2897–902. http://dx.doi.org/10.1002/adsc.200900550.

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31

INOUE, I., M. SHINDO, K. KOGA y K. TOMIOKA. "ChemInform Abstract: Asymmetric 1,2-Addition of Organolithiums to Aldimines Catalyzed by a Chiral Ligand." ChemInform 25, n.º 33 (19 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199433049.

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32

Znovjyak, Kateryna, Maksym Seredyuk, Sergey O. Malinkin, Iryna O. Golenya, Vladimir M. Amirkhanov, Sergiu Shova y Nurullo U. Mulloev. "Crystal structure of {N 1,N 3-bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methylidene]-2,2-dimethylpropane-1,3-diamine}bis(thiocyanato)iron(II)". Acta Crystallographica Section E Crystallographic Communications 77, n.º 5 (30 de abril de 2021): 573–78. http://dx.doi.org/10.1107/s2056989021004412.

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The unit cell of the title compound, [FeII(NCS)2(C19H32N8)], consists of two charge-neutral complex molecules. In the complex molecule, the tetradentate ligand N 1 ,N 3-bis[(1-tert-butyl-1H-1,2,3-triazol-4-yl)methylene]-2,2-dimethylpropane-1,3-diamine coordinates to the FeII ion through the N atoms of the 1,2,3-triazole and aldimine groups. Two thiocyanate anions, also coordinated through their N atoms, complete the coordination sphere of the central Fe ion. In the crystal, neighbouring molecules are linked through weak C—H...C/S/N interactions into a three-dimensional network. The intermolecular contacts were quantified using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H...H 50.8%, H...C/C...H 14.3%, H...S/S...H 20.5% and H...N/N...H 12.1%. The average Fe—N bond distance is 2.170 Å, indicating the high-spin state of the FeII ion, which does not change upon cooling, as demonstrated by low-temperature magnetic susceptibility measurements. DFT calculations of energy frameworks at the B3LYP/6–31 G(d,p) theory level were performed to account for the interactions involved in the crystal structure.
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33

Niemeyer, Jochen, Gerald Kehr, Roland Fröhlich y Gerhard Erker. "Selective synthesis of the 2-hydroxyferrocene-aldimine enantiomers—extended planar chiral analogues of the “flat” salicylaldimine ligand family". Dalton Transactions, n.º 19 (2009): 3716. http://dx.doi.org/10.1039/b822735g.

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34

Bailey, Philip J., Daniel Loroño-González y Simon Parsons. "6-Aminofulvene-2-aldimine, a novel class of ambidentate cyclopentadienyl/diimine ligand: synthesis and characterisation of magnesium complexes". Chem. Commun., n.º 12 (2003): 1426–27. http://dx.doi.org/10.1039/b303540a.

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35

Zhao, Qian-Yi y Min Shi. "Axially chiral phosphine–oxazoline ligands in silver(I)-catalyzed asymmetric Mannich reaction of N-Boc aldimines with trimethylsiloxyfuran". Tetrahedron 67, n.º 20 (mayo de 2011): 3724–32. http://dx.doi.org/10.1016/j.tet.2011.03.046.

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36

Zhao, Qian-Yi, Zhi-Liang Yuan y Min Shi. "Axially chiral phosphine–oxazoline ligands in the silver(I)-catalyzed asymmetric Mannich reaction of fluorinated aldimines with trimethylsiloxyfuran". Tetrahedron: Asymmetry 21, n.º 8 (abril de 2010): 943–51. http://dx.doi.org/10.1016/j.tetasy.2010.05.025.

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37

Shindo, Mitsuru, Kenji Koga y Kiyoshi Tomioka. "Design, Synthesis, and Application of aC2Symmetric Chiral Ligand for Enantioselective Conjugate Addition of Organolithium to α,β-Unsaturated Aldimine". Journal of Organic Chemistry 63, n.º 25 (diciembre de 1998): 9351–57. http://dx.doi.org/10.1021/jo9813181.

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38

Liu, Yi-Chang, Chia-Her Lin, Bao-Tsan Ko y Rong-Ming Ho. "Ring-opening polymerization of β-butyrolactone catalyzed by efficient magnesium and zinc complexes derived from tridentate anilido-aldimine ligand". Journal of Polymer Science Part A: Polymer Chemistry 48, n.º 23 (5 de octubre de 2010): 5339–47. http://dx.doi.org/10.1002/pola.24334.

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39

NAKAMURA, M., A. HIRAI y E. NAKAMURA. "ChemInform Abstract: Enantioselective Allylzincation of Cyclic Aldimines in the Presence of an Anionic Bis-oxazoline Ligand." ChemInform 28, n.º 2 (4 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199702065.

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40

Sun, Weiye, Haorui Gu y Xufeng Lin. "Synthesis and Application of Hexamethyl-1,1′-spirobiindane-Based Phosphine-Oxazoline Ligands in Ni-Catalyzed Asymmetric Arylation of Cyclic Aldimines". Journal of Organic Chemistry 83, n.º 7 (19 de marzo de 2018): 4034–43. http://dx.doi.org/10.1021/acs.joc.8b00422.

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41

Jackson, Deneikah T., Peter N. Nelson, Kimberly Weston y Richard A. Taylor. "Preparation and Properties of Three Plasticiser-Free Novel Di-benzo-18-Crown-6 Aldimine-Derived Lead(II) Ion-Selective Electrodes". Inorganics 11, n.º 7 (27 de junio de 2023): 275. http://dx.doi.org/10.3390/inorganics11070275.

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Three novel dibenzo-18-crown-6 aldimines were successfully synthesised and structurally characterised via various spectroscopic methods (1H,13H NMR, FT-IR) and their solution phase lead binding behaviours probed via absorption spectroscopy, the results are supported by Density Functional Theoretical (DFT) modelling. These methods revealed that the asymmetric nature of these compounds is such that at equilibrium the ether cavity adopts an open configuration where the constituent oxygen atoms exhibit a highly negative electrostatic potential; hence, they spontaneously (ΔG~−58 kJ mol−1) interact/bind aqueous lead ions to form stable 2:1 metal–ligand complexes. As indicated by cyclic and square voltammetry studies, all compounds are redox active and polymerise relatively easily onto a platinum surface to form a multi-layered lead Ion-selective Membrane (ISM), the structure of which is confirmed by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). These novel Ion-selective Electrodes (ISEs), as characterised by Differential Pulse Anodic Stripping Voltammetry (D PASV), allow selective electrochemical detection and quantification of lead at concentrations as low as 10 ppm, over a range of 15–60 ppm, with only minimal interference from mercury(II) and aluminium(III) ions at a 1:1 analyte-interferent ratio.
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42

Shan, Huanyu, Qiaoxia Zhou, Jinglu Yu, Shuoqing Zhang, Xin Hong y Xufeng Lin. "Rhodium-Catalyzed Asymmetric Addition of Organoboronic Acids to Aldimines Using Chiral Spiro Monophosphite-Olefin Ligands: Method Development and Mechanistic Studies". Journal of Organic Chemistry 83, n.º 19 (28 de agosto de 2018): 11873–85. http://dx.doi.org/10.1021/acs.joc.8b01764.

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43

Zhao, Qian-Yi y Min Shi. "ChemInform Abstract: Axially Chiral Phosphine-Oxazoline Ligands in Silver(I)-Catalyzed Asymmetric Mannich Reaction of N-Boc Aldimines with Trimethylsiloxyfuran." ChemInform 42, n.º 39 (1 de septiembre de 2011): no. http://dx.doi.org/10.1002/chin.201139080.

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44

Zhao, Qian-Yi, Zhi-Liang Yuan y Min Shi. "ChemInform Abstract: Axially Chiral Phosphine-Oxazoline Ligands in the Silver(I)-Catalyzed Asymmetric Mannich Reaction of Fluorinated Aldimines with Trimethylsiloxyfuran." ChemInform 41, n.º 49 (11 de noviembre de 2010): no. http://dx.doi.org/10.1002/chin.201049093.

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45

Tomioka, Kiyoshi, Seiji Hata, Tetsuo Iwasawa, Mayu Iguchi y Ken-ichi Yamada. "Catalytic Enhancement Effect of a Chiral Ligand on the Asymmetric Mannich­-Type Reactions of Menthyl Alkanoates with Aldimines". Synthesis 2004, n.º 09 (2004): 1471–75. http://dx.doi.org/10.1055/s-2004-822365.

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46

Russell, Sarah K., Carsten Milsmann, Emil Lobkovsky, Thomas Weyhermüller y Paul J. Chirik. "Synthesis, Electronic Structure, and Catalytic Activity of Reduced Bis(aldimino)pyridine Iron Compounds: Experimental Evidence for Ligand Participation". Inorganic Chemistry 50, n.º 7 (4 de abril de 2011): 3159–69. http://dx.doi.org/10.1021/ic102186q.

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47

Jagt, Richard B. C., Patrick Y. Toullec, Danny Geerdink, Johannes G. de Vries, Ben L. Feringa y Adriaan J. Minnaard. "A Ligand-Library Approach to the Highly Efficient Rhodium/Phosphoramidite-Catalyzed Asymmetric Arylation ofN,N-Dimethylsulfamoyl-Protected Aldimines". Angewandte Chemie International Edition 45, n.º 17 (21 de abril de 2006): 2789–91. http://dx.doi.org/10.1002/anie.200504309.

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48

Zhang, Xu, Bin Xu y Ming-Hua Xu. "Rhodium-catalyzed asymmetric arylation of N- and O-containing cyclic aldimines: facile and efficient access to highly optically active 3,4-dihydrobenzo[1,4]oxazin-2-ones and dihydroquinoxalinones". Organic Chemistry Frontiers 3, n.º 8 (2016): 944–48. http://dx.doi.org/10.1039/c6qo00191b.

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49

Bailey, Philip J., Michele Melchionna y Simon Parsons. "Ambidentate Character of the 6-Aminofulvene-2-aldiminate Ligand Containing Both Diimine and Cyclopentadienyl Donors". Organometallics 26, n.º 1 (enero de 2007): 128–35. http://dx.doi.org/10.1021/om060808d.

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50

Yuan, Zhi-Liang, Jia-Jun Jiang y Min Shi. "The application of chiral phosphine-Schiff base type ligands in silver(I)-catalyzed asymmetric vinylogous Mannich reaction of aldimines with trimethylsiloxyfuran". Tetrahedron 65, n.º 31 (agosto de 2009): 6001–7. http://dx.doi.org/10.1016/j.tet.2009.05.080.

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