A direct method for the <i>N</i>-tetraalkylation of azamacrocycles

Counsell, Andrew J.; Jones, Angus; Todd, Matthew H.; Rutledge, Peter J.

doi:10.3762/bjoc.12.239

Cited by 11 publications

(5 citation statements)

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“…75 The ligand, 12-TBC (= 1,4,7,10tetrabenzyl-1,4,7,10-tetraazacyclododecane), was synthesized by a previously reported method. 76 Co II (12-TBC)(OTf) 2 (1) was synthesized in a drybox: Equimolar amounts of 12-TBC (0.28 mmol, 150 and Co II (CF 3 SO 3 ) 2 •2CH 3 CN (0.28 mmol, 120 mg) were dissolved in CH 3 CN and stirred at ambient temperature for 12 h in a drybox, resulting in a color change of the reaction solution to red. The resulting solution was filtered and a large volume of ether was added to the solution, giving the red precipitate of the desired product.…”

Section: Methodsmentioning

confidence: 99%

“…Co II (OTf) 2 ·2CH 3 CN was synthesized according to a literature method . The ligand, 12-TBC (= 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane), was synthesized by a previously reported method . Co II (12-TBC)(OTf) 2 ( 1 ) was synthesized in a drybox: Equimolar amounts of 12-TBC (0.28 mmol, 150 mg) and Co II (CF 3 SO 3 ) 2 ·2CH 3 CN (0.28 mmol, 120 mg) were dissolved in CH 3 CN and stirred at ambient temperature for 12 h in a drybox, resulting in a color change of the reaction solution to red.…”

Section: Methodsmentioning

confidence: 99%

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The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)–Oxo Complex

et al. 2021

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In this paper, we report the preparation, spectroscopic and theoretical characterization, and reactivity studies of a Co(IV)−oxo complex bearing an N4-macrocyclic coligand, 12-TBC (12-TBC = 1,4,7,10-tetrabenzyl-1,4,7,10-tetraazacyclododecane). On the basis of the ligand and the structure of the Co(II) precursor, [Co II (12-TBC)(CF 3 SO 3 ) 2 ], one would assume that this species corresponds to a tetragonal Co(IV)−oxo complex, but the spectroscopic data do not support this notion. Co K-edge XAS data show that the treatment of the Co(II) precursor with iodosylbenzene (PhIO) as an oxidant at −40 °C in the presence of a proton source leads to a distinct shift in the Co K-edge, in agreement with the formation of a Co(IV) intermediate. The presence of the oxo group is further demonstrated by resonance Raman (rRaman) spectroscopy. Interestingly, the EPR data of this complex show a high degree of rhombicity, indicating structural distortion. This is further supported by the EXAFS data. Using DFT calculations, a structural model is developed for this complex with a ligand-protonated structure that features a CoO•••HN hydrogen bond and a four-coordinate Co center in a seesaw-shaped coordination geometry. Magnetic circular dichroism (MCD) spectroscopy further supports this finding. The hydrogen bond leads to an interesting polarization of the Co−oxo π-bonds, where one O(p) lone-pair is stabilized and leads to a regular Co(d) interaction, whereas the other π-bond shows an inverted ligand field. The reactivity of this complex in hydrogen atom and oxygen atom transfer reactions is discussed as well.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)–Oxo Complex

et al. 2021

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“…1H NMR (400 MHz, CDCl3) δ 7.52 (d, J = 8.1 Hz, 2H), 7.43 (d, J = 8.1 Hz, 2H), 6.69 (d, J = 4.1 Hz, 2H), 6.27 (d, J = 4.1 Hz, 2H), 4.46 (s, 2H), 2.65 (s, 6H). Step 3: Synthesis of 1,4,8,11-Tetra(prop-2-yn-1-yl)-1,4,8,11-tetraazacyclotetradecane based on (Counsell et al, 2016). To a solution of 1,4,8,11-tetraazacyclotetradecane (500 mg, 2.49 mmol) in 5 mL of acetonitrile 5 mL of 1M NaOH was added followed by 1.1 mL 80% propargyl bromide solution (in toluene, 10.2 mmol).…”

Section: Methodsmentioning

confidence: 99%

Cell wall extensin arabinosylation is required for root directional response to salinity

Zou

Gigli-Bisceglia

Zelm

et al. 2022

Preprint

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Soil salinity is a major contributor to crop yield losses. To improve our understanding of root responses to salinity, we developed and exploit here a real-time salt-induced tilting assay (SITA). This method follows root growth upon both gravitropic and salt challenges and revealed that root bending is modulated by salinity, but not by osmotic stress. Next, this salt-specific response was measured in 345 natural Arabidopsis accessions and we discovered a genetic locus, encoding for the cell-wall modifying enzyme Extensin Arabinose Deficient arabinosyltransferase (ExAD), to be associated with root bending in salt. Extensins are a class of structural cell wall glycoproteins [hydroxyproline-rich glycoproteins (HRGPs)] which are post-translationally modified by O-glycosylation mostly in the form of hydroxyproline (Hyp)-arabinosylation. Here we show that salt induces ExAD-dependent Hyp-arabinosylation, influencing root bending responses and cell wall thickness. We report that exad mutants, which lack all cell wall Hyp-Araf4 modifications, display increased root epidermal cell wall thickness, and are impaired in the salt-dependent root bending response. Our study thus demonstrates a requirement for extensin Hyp-arabinosylation as a novel cell wall modification for the salt-specific directional response of roots and provides new insight into the process of how plant roots sense and respond to salinity.

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“…In recent years, cyclen and related macrocyclic polyamines have been greatly explored as a promising vehicle of radio nuclides in radio immunotherapy (RIT), single-photon emission computed tomography (SPECT), and positron [18]. e easy N-alkylation of cyclens facilitates significant alteration in the macrocycles for the development of promising hypercore of wide applications [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Dinuclear Copper(I) Thiodiacetate Complex-Mediated Expeditious Synthesis of the Chlorine-Containing Cyclen-Cored 36-Glucose-Coated Glycodendrimer

Agrahari

Kumar

Sharma

et al. 2021

Journal of Chemistry

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High-sugar-tethered glycodendrimers are a remarkable tool in glycobiology for the investigation of carbohydrate-protein interaction using its multivalency property. An enthralling double-stage convergent synthetic approach was selected to build a novel class of chlorine-containing glucose-coated dendrimers using an efficient click catalyst ‘dinuclear copper(I) thiodiacetate complex.’ In this context, cyclen core was developed through a divergent approach, while the glucodendron was developed via a convergent approach independently. Both azide-alkyne partners were coupled through a modular copper azide-alkyne cycloaddition (CuAAC) strategy to afford a high yield of the desired 36-glucose-coated glycodendrimer. The synthesized glycodendrimer has been elucidated by NMR, gel permeation chromatography (GPC), and IR spectral analysis.

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A direct method for the N-tetraalkylation of azamacrocycles

Cited by 11 publications

References 50 publications

The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)–Oxo Complex

The Oxo-Wall Remains Intact: A Tetrahedrally Distorted Co(IV)–Oxo Complex

Cell wall extensin arabinosylation is required for root directional response to salinity

Dinuclear Copper(I) Thiodiacetate Complex-Mediated Expeditious Synthesis of the Chlorine-Containing Cyclen-Cored 36-Glucose-Coated Glycodendrimer

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