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Search for "ESR spectroscopy" in Full Text gives 6 result(s) in Beilstein Journal of Organic Chemistry.
Tying a knot between crown ethers and porphyrins
- Maksym Matviyishyn and
- Bartosz Szyszko
Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120
- ) and Co(II), into the porphyrin core introduced a probe, which enabled ESR spectroscopy methods as a means of the analysis of the assembled complexes with cationic guests bound within the crown ether pockets. Over the years, several groups have shown interesting chemistry of meso-crowned porphyrins
Graphical Abstract
Figure 1: Porphyrin and crown ether.
Figure 2: Timeline demonstrating the contributions into the crown ether–porphyrin chemistry.
Figure 3: Tetra-crowned porphyrin 1 and dimer 2 formed upon K+ binding.
Figure 4: meso-Crowned 25-oxasmaragdyrins 3a–c and their boron(III) complexes (3a–c)-BF2.
Scheme 1: CsF ion-pair binding of 4. The molecular structure of 4-CsF is shown on the right [101].
Figure 5: CsF ion pair binding by 5. The molecular structure of 5-CsF is shown on the right [102].
Scheme 2: Ion-pair binding by 6. The molecular structure of (6-CsCl)2 is shown on the right [103].
Scheme 3: Hydrated fluoride binding by 7 [104].
Figure 6: β-Crowned porphyrin 8.
Figure 7: Crown ether-capped porphyrins 9.
Figure 8: The capped porphyrin 10 and complex [10-PQ](PF6)2.
Figure 9: The double-capped porphyrin 11.
Figure 10: Selected examples of iminoporphyrinoids [58,122].
Scheme 4: The synthesis of 13.
Scheme 5: Tripyrrane-based crown ether-embedding porphyrinoid 15.
Figure 11: Macrocycles 16–19 and their coordination compounds.
Scheme 6: The flexibility of 16-Co [66].
Figure 12: Hexagonal wheel composed of six 16-Co(III) monomers [66].
Scheme 7: The synthesis of 16-V [67].
Figure 13: The molecular structure of dimers [16-Mn]2 [67].
Scheme 8: Synthesis of crownphyrins 28–33. Compounds 23a/b and 29a/b were obtained from 4,7,10-trioxa-1,13-tr...
Figure 14: The molecular structures of 22a, 34a·(HCl)2, and 29b [69].
Figure 15: Molecular structures of 22a-Pb and (29b)2-Zn [69].
Scheme 9: Reactivity of 29a/b.
Scheme 10: Synthesis of 36 and 37 [131].
Scheme 11: Synthesis of 40–45.
Figure 16: Potential applications of porphyrin-crown ether hybrids.
Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole
- Martina Tireli,
- Silvija Maračić,
- Stipe Lukin,
- Marina Juribašić Kulcsár,
- Dijana Žilić,
- Mario Cetina,
- Ivan Halasz,
- Silvana Raić-Malić and
- Krunoslav Užarević
Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232
- spin resonance (ESR) spectroscopy; in situ Raman monitoring; mechanochemistry; quinoline; solid-state click chemistry; Introduction The copper-catalyzed azide–alkyne cycloaddition (CuAAC) represents a prime example of click chemistry. Click chemistry describes “a set of near-perfect” reactions [1] for
- milling CuAAC reaction pathway when using different catalysts. The electronic structure of Cu catalysts after the reaction completion was assayed by electron spin resonance (ESR) spectroscopy. All milling reactions, except the one using copper(0) as catalyst, were compared to solution procedures to
- in complete conversions of reactants to the triazole products with the isolated yields ranging from 80–90%. After the isolation and purification, copper-sensitive ESR spectroscopy showed no traces of copper in the products (Materials and methods within the Experimental section). Compared to solution
Graphical Abstract
Scheme 1: Synthetic procedures for preparation of p-halogen-substituted and non-substituted phenyl-1,2,3-tria...
Figure 1: Experimental Raman spectra of the alkyne 4 and triazole products 5–8. Bands attributed to the vibra...
Figure 2: In situ Raman monitoring of a) mechanochemical formation of triazole 5 using copper(II) acetate mon...
Figure 3: a) In situ Raman monitoring for mechanochemical synthesis of 5 using brass balls and PMMA reaction ...
Figure 4: ESR spectra of samples obtained after milling by methods 2a (black), 2b (red) and 2c (blue). The in...
Figure 5: X-ray structure of the triazole compounds. (a) Molecular structure of 5, with the atom-numbering sc...
Kinetic analysis of mechanoradical formation during the mechanolysis of dextran and glycogen
- Naoki Doi,
- Yasushi Sasai,
- Yukinori Yamauchi,
- Tetsuo Adachi,
- Masayuki Kuzuya and
- Shin-ichi Kondo
Beilstein J. Org. Chem. 2017, 13, 1174–1183, doi:10.3762/bjoc.13.116
- of a polymer at a temperature below its glass-transition temperature (Tg) due to the disruption of the polymer main chain [1]. Although most pulverization operations for a practical use are carried out at room temperature, electron spin resonance (ESR) spectroscopy analyses of mechanoradical
Graphical Abstract
Figure 1: Structures of discrete mechanoradicals and the reaction sequence for their formation from cellulose ...
Figure 2: Schematic structure of amylose, dextran and glycogen.
Figure 3: Progressive changes in observed ESR spectra of fractured amylose [5], Dx, and Gly, together with simul...
Figure 4: Schematic representation of bond cleavage at α-1,4- and α-1,6-bonds.
Figure 5: ESR spectrum of fractured sample of Dx and TCNE (a) before and (b) after visible-light irradiation.
Figure 6: Component spectra of the simulated ESR spectra.
Figure 7: Progressive changes in the intensity of component spectra corresponding to the simulated spectra of...
Figure 8: Changes in Dx molecular-weight distribution (MWD) during vibratory milling.
Figure 9: Changes in Dx weight-average molecular weight (Mw) during vibratory milling.
Figure 10: Change in Gly particle diameter during vibratory milling.
TEMPO-derived spin labels linked to the nucleobases adenine and cytosine for probing local structural perturbations in DNA by EPR spectroscopy
- Dnyaneshwar B. Gophane and
- Snorri Th. Sigurdsson
Beilstein J. Org. Chem. 2015, 11, 219–227, doi:10.3762/bjoc.11.24
- paired with A, G, C or T in a DNA duplex. UA and UC had similar mobility order for the different base pairs, with the lowest mobility when paired with C and the highest when paired with T. Keywords: aminoxyl radical; ESR spectroscopy; nitroxide; nucleic acids; site-directed spin labeling (SDSL); spin
Graphical Abstract
Figure 1: Base pairing of TC with G (A), TA with T (B), UC with G (C) and UA with T (D).
Scheme 1: Synthesis of nucleoside TA and its corresponding phosphoramidite 5. TPS = 2,4,6-triisopropylbenzene...
Scheme 2: Synthesis of nucleoside UA and its corresponding phosphoramidite 10.
Scheme 3: Synthesis of nucleoside UC and its corresponding phosphoramidite 14.
Figure 2: EPR spectra of 14-mer DNA duplexes 5′-d(GACCTCGTAATCGTG)•5′-d(CACGATYCGAGGTC), (10 mM phosphate, 10...
Figure 3: Possible base pairing of TAH+ with C (A) and G (B) at pH 5.
Figure 4: Possible base pairing of UA and UC with C.
Figure 5: EPR spectra of 14-mer DNA duplex 5′-d(GACCTCGUAATCGTG)•5′-d(CACGATYCGAGGTC) (A), and 5′-d(GACCTCGUC...
Cross-dehydrogenative coupling for the intermolecular C–O bond formation
- Igor B. Krylov,
- Vera A. Vil’ and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13
- radical 168 to give radical 169 and the oxidation of the latter resulted in the formation of coupling product 170 (Scheme 34). Radical intermediates 168 and 169 were detected by ESR spectroscopy [149]. The oxidative coupling of aldehydes 171 with pivalic acid (172) was performed using the TEMPOcat/t-BuOCl
- reagents. The formation of N-oxyl radicals 212 and 207 from oximes and N-hydroxyimides was confirmed by ESR spectroscopy [197][198]. The oxidative coupling of 1,3-dicarbonyl compounds [199] and their hetero analogues [200] 213 with tert-butyl hydroperoxides catalyzed by transition metal salts (Cu, Fe, Co
Graphical Abstract
Scheme 1: Cross-dehydrogenative coupling.
Scheme 2: Cross-dehydrogenative C–O coupling.
Scheme 3: Regioselective ortho-acetoxylation of meta-substituted arylpyridines and N-arylamides.
Scheme 4: ortho-Acyloxylation and alkoxylation of arenes directed by pyrimidine, benzoxazole, benzimidazole a...
Scheme 5: Cu(OAc)2/AgOTf/O2 oxidative system in the ortho-alkoxylation of arenes.
Scheme 6: Pd(OAc)2/persulfate oxidative system in the ortho-alkoxylation and acetoxylation of arenes with nit...
Scheme 7: ortho-Acetoxylation and methoxylation of O-methyl aryl oximes, N-phenylpyrrolidin-2-one, and (3-ben...
Scheme 8: Ruthenium-catalyzed ortho-acyloxylation of acetanilides.
Scheme 9: Acetoxylation and alkoxylation of arenes with amide directing group using Pd(OAc)2/PhI(OAc)2 oxidat...
Scheme 10: Alkoxylation of azoarenes, 2-aryloxypyridines, picolinamides, and N-(1-methyl-1-(pyridin-2-yl)ethyl...
Scheme 11: Acetoxylation of compounds containing picolinamide and quinoline-8-amine moieties using the Pd(OAc)2...
Scheme 12: (CuOH)2CO3 catalyzed oxidative ortho-etherification using air as oxidant.
Scheme 13: Copper-catalyzed aerobic alkoxylation and aryloxylation of arenes containing pyridine-N-oxide moiet...
Scheme 14: Cobalt-catalyzed aerobic alkoxylation of arenes and alkenes containing pyridine N-oxide moiety.
Scheme 15: Non-symmetric double-fold C–H ortho-acyloxylation.
Scheme 16: N-nitroso directed ortho-alkoxylation of arenes.
Scheme 17: Selective alkoxylation and acetoxylation of alkyl groups.
Scheme 18: Acetoxylation of 2-alkylpyridines and related compounds.
Scheme 19: Acyloxylation and alkoxylation of alkyl fragments of substrates containing amide or sulfoximine dir...
Scheme 20: Palladium-catalyzed double sp3 C–H alkoxylation of N-(quinolin-8-yl)amides for the synthesis of sym...
Scheme 21: Copper-catalyzed acyloxylation of methyl groups of N-(quinolin-8-yl)amides.
Scheme 22: One-pot acylation and sp3 C–H acetoxylation of oximes.
Scheme 23: Possible mechanism of oxidative esterification catalyzed by N-heterocyclic nucleophilic carbene.
Scheme 24: Oxidative esterification employing stoichiometric amounts of aldehydes and alcohols.
Scheme 25: Selective oxidative coupling of aldehydes with alcohols in the presence of amines.
Scheme 26: Iodine mediated oxidative esterification.
Scheme 27: Oxidative C–O coupling of benzyl alcohols with methylarenes under the action of Bu4NI/t-BuOOH syste...
Scheme 28: Oxidative coupling of methyl- and ethylarenes with aromatic aldehydes under the action of Bu4NI/t-B...
Scheme 29: Cross-dehydrogenative C–O coupling of aldehydes with t-BuOOH in the presence of Bu4NI.
Scheme 30: Bu4NI-catalyzed α-acyloxylation reaction of ethers and ketones with aldehydes and t-BuOOH.
Scheme 31: Oxidative coupling of aldehydes with N-hydroxyimides and hexafluoroisopropanol.
Scheme 32: Oxidative coupling of alcohols with N-hydroxyimides.
Scheme 33: Oxidative coupling of aldehydes and primary alcohols with N-hydroxyimides using (diacetoxyiodo)benz...
Scheme 34: Proposed mechanism of the oxidative coupling of aldehydes and N-hydroxysuccinimide under action of ...
Scheme 35: Oxidative coupling of aldehydes with pivalic acid (172).
Scheme 36: Oxidative C–O coupling of aldehydes with alkylarenes using the Cu(OAc)2/t-BuOOH system.
Scheme 37: Copper-catalyzed acyloxylation of C(sp3)-H bond adjacent to oxygen in ethers using benzyl alcohols.
Scheme 38: Oxidative C–O coupling of aromatic aldehydes with cycloalkanes.
Scheme 39: Ruthenium catalyzed cross-dehydrogenative coupling of primary and secondary alcohols.
Scheme 40: Cross-dehydrogenative C–O coupling reactions of β-dicarbonyl compounds with sulfonic acids, acetic ...
Scheme 41: Acyloxylation of ketones, aldehydes and β-dicarbonyl compounds using carboxylic acids and Bu4NI/t-B...
Scheme 42: Acyloxylation of ketones using Bu4NI/t-BuOOH system.
Scheme 43: Cross-dehydrogenative C–O coupling of β-dicarbonyl compounds and their heteroanalogues with N-hydro...
Scheme 44: Cross-dehydrogenative C–O coupling of β-dicarbonyl compounds and their heteroanalogues with t-BuOOH....
Scheme 45: Oxidative C–O coupling of 2,6-dialkylphenyl-β-keto esters and thioesters with tert-butyl hydroxycar...
Scheme 46: α’-Acyloxylation of α,β-unsaturated ketones using KMnO4.
Scheme 47: Possible mechanisms of the acetoxylation at the allylic position of alkenes by Pd(OAc)2.
Scheme 48: Products of the oxidation of terminal alkenes by Pd(II)/AcOH/oxidant system.
Scheme 49: Acyloxylation of terminal alkenes with carboxylic acids.
Scheme 50: Synthesis of linear E-allyl esters by cross-dehydrogenative coupling of terminal alkenes wih carbox...
Scheme 51: Pd(OAc)2-catalyzed acetoxylation of Z-vinyl(triethylsilanes).
Scheme 52: α’-Acetoxylation of α-acetoxyalkenes with copper(II) chloride in acetic acid.
Scheme 53: Oxidative acyloxylation at the allylic position of alkenes and at the benzylic position of alkylare...
Scheme 54: Copper-catalyzed alkoxylation of methylheterocyclic compounds using di-tert-butylperoxide as oxidan...
Scheme 55: Oxidative C–O coupling of methylarenes with β-dicarbonyl compounds or phenols.
Scheme 56: Copper-catalyzed esterification of methylbenzenes with cyclic ethers and cycloalkanes.
Scheme 57: Oxidative C–O coupling of carboxylic acids with toluene catalyzed by Pd(OAc)2.
Scheme 58: Oxidative acyloxylation at the allylic position of alkenes with carboxylic acids using the Bu4NI/t-...
Scheme 59: Cross-dehydrogenative C–O coupling of carboxylic acids with alkylarenes using the Bu4NI/t-BuOOH sys...
Scheme 60: Oxidative C–O cross-coupling of methylarenes with ethyl or isopropylarenes.
Scheme 61: Phosphorylation of benzyl C–H bonds using the Bu4NI/t-BuOOH oxidative system.
Scheme 62: Selective C–H acetoxylation of 2,3-disubstituted indoles.
Scheme 63: Acetoxylation of benzylic position of alkylarenes using DDQ as oxidant.
Scheme 64: C–H acyloxylation of diarylmethanes, 3-phenyl-2-propen-1-yl acetate and dimethoxyarene using DDQ.
Scheme 65: Cross-dehydrogenative C–O coupling of 1,3-diarylpropylenes and 1,3-diarylpropynes with alcohols.
Scheme 66: One-pot azidation and C–H acyloxylation of 3-chloro-1-arylpropynes.
Scheme 67: Cross-dehydrogenative C–O coupling of 1,3-diarylpropylenes, (E)-1-phenyl-2-isopropylethylene and is...
Scheme 68: Cross-dehydrogenative C–O coupling of alkylarenes and related compounds with N-hydroxyphthalimide.
Scheme 69: Acetoxylation at the benzylic position of alkylarenes mediated by N-hydroxyphthalimide.
Scheme 70: C–O coupling of methylarenes with aromatic carboxylic acids employing the NaBrO3/NaHSO3 system.
Scheme 71: tert-Butyl peroxidation of allyl, propargyl and benzyl ethers catalyzed by Fe(acac)3.
Scheme 72: Cross-dehydrogenative C–O coupling of ethers with carboxylic acids mediated by Bu4NI/t-BuOOH system....
Scheme 73: Oxidative acyloxylation of dimethylamides and dioxane with 2-aryl-2-oxoacetic acids accompanied by ...
Scheme 74: tert-Butyl peroxidation of N-benzylamides and N-allylbenzamide using the Bu4NI/t-BuOOH system.
Scheme 75: Cross-dehydrogenative C–O coupling of aromatic carboxylic acids with ethers using Fe(acac)3 as cata...
Scheme 76: Cross-dehydrogenative C–O coupling of cyclic ethers with 2-hydroxybenzaldehydes using iron carbonyl...
Scheme 77: Cross-dehydrogenative C–O coupling of ethers with β-dicarbonyl compounds and phenols using copper c...
Scheme 78: Cross-dehydrogenative C–O coupling of 2-hydroxybenzaldehyde with dioxane catalyzed by Cu2(BPDC)2(BP...
Scheme 79: Ruthenium chloride-catalyzed acyloxylation of β-lactams.
Scheme 80: Ruthenium-catalyzed tert-butyl peroxydation amides and acetoxylation of β-lactams.
Scheme 81: PhI(OAc)2-mediated α,β-diacetoxylation of tertiary amines.
Scheme 82: Electrochemical oxidative methoxylation of tertiary amines.
Scheme 83: Cross-dehydrogenative C–O coupling of ketene dithioacetals with carboxylic acids in the presence of...
Scheme 84: Cross-dehydrogenative C–O coupling of enamides with carboxylic acids using iodosobenzene as oxidant....
Scheme 85: Oxidative alkoxylation, acetoxylation, and tosyloxylation of acylanilides using PhI(O(O)CCF3)2 in t...
Scheme 86: Proposed mechanism of the oxidative C–O coupling of actetanilide with O-nucleophiles in the presenc...
Scheme 87: Three-component coupling of aldehydes, anilines and alcohols involving oxidative intermolecular C–O...
Scheme 88: Oxidative coupling of phenols with alcohols.
Scheme 89: 2-Acyloxylation of quinoline N-oxides with arylaldehydes in the presence of the CuOTf/t-BuOOH syste...
Scheme 90: Cross-dehydrogenative C–O coupling of azoles with primary alcohols.
Scheme 91: Oxidation of dipyrroles to dipyrrins and subsequent oxidative alkoxylation in the presence of Na3Co...
Scheme 92: Oxidative dehydrogenative carboxylation of alkanes and cycloalkanes to allylic esters.
Scheme 93: Pd-catalyzed acetoxylation of benzene.
4-Pyridylnitrene and 2-pyrazinylcarbene
- Curt Wentrup,
- Ales Reisinger and
- David Kvaskoff
Beilstein J. Org. Chem. 2013, 9, 754–760, doi:10.3762/bjoc.9.85
- phenylnitrene (1) and 2-pyridylcarbene (3) has been described in considerable detail [1][2][3]. The three species 1–3 have all been observed directly by IR or ESR spectroscopy in low-temperature matrices. The normal reaction products of phenylnitrene are azobenzene (4) and aniline (5), but under forcing flash
Graphical Abstract
Scheme 1: Phenylnitrene–2-pyridylcarbene rearrangement.
Scheme 2: Type I and type II ring opening and ring expansion in 3- and 2-pyridylnitrenes, respectively.
Scheme 3: FVT reactions of 4-azidopyridine (18), 2-(5-tetrazolyl)pyrazine (23) and triazolo[1,5-a]pyrazine (24...
Figure 1: Difference-IR spectrum of 2-diazomethylpyrazine (22) (positive peaks) in Ar matrix at 7 K, obtained...
Figure 2: Ar matrix IR-difference spectra showing the products of broadband UV photolysis of 4-azidopyridine (...
Figure 3: Top: calculated IR spectrum of 20 at the B3LYP/6-31G* level (wavenumbers scaled by 0.9613): ν’ (rel...
Figure 4: Bottom: IR spectrum from the matrix photolysis of azide 18 after the azide has been depleted comple...
Scheme 4: Photolysis reactions of azide 18 and triazole 24 in Ar matrix.
