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Search for "sensors" in Full Text gives 188 result(s) in Beilstein Journal of Organic Chemistry.
Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks
- Zhang Dongxu
Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127
- of several diseases [28][29][30]. They have also been applied in the field of materials science, especially for the synthesis of metal and covalent organic frameworks, dyes, hole-transporting materials and sensors, and in dynamic combinatorial chemistry [31], indicating a wide applicability
Graphical Abstract
Scheme 1: Synthesis of trifluoromethylpyrazoles from trifluoroacetaldehyde hydrazones.
Scheme 2: Synthesis of polysubstituted pyrazolidines and pyrazolines.
Scheme 3: Asymmetric synthesis of 3-trifluoromethyl-1,4-dihydropyridazines reported by Rueping et al. [39].
Scheme 4: Synthesis of 3-trifluoromethyl-1,4-dihydropyridazine with Brønsted acid-assisted Lewis base catalys...
Scheme 5: Synthesis of CF3-pyrazoles and CF3-1,6-dihydropyridazines.
Scheme 6: Asymmetric reactions of trifluoromethylimines with organometallic reagents.
Scheme 7: Mannich-type reaction of trifluoroacetaldehyde hydrazones.
Scheme 8: Synthesis of trifluoromethylated hydrazonoyl halides.
Scheme 9: Early work of trifluoromethylated hydrazonoyl halides.
Scheme 10: [3 + 2]/[3 + 3] Cycloadditions of trifluoromethylated hydrazonoyl halides.
Scheme 11: Substrate scope for [3 + 2] cycloadditions with trifluoroacetonitrile imines reported by Jasiński’s...
Scheme 12: Synthesis of trifluoromethylated 1,2,4-triazole and 1,2,4-triazine derivatives.
Scheme 13: [3 + 2] Cycloadditions of difluoromethylated hydrazonoyl halides.
Scheme 14: Preparation and early applications of trifluoromethylated acylhydrazones.
Scheme 15: 1,2-Nucleophilic addition reactions of trifluoromethylated acylhydrazones.
Scheme 16: Cascade oxidation/cyclization reactions of trifluoromethylated homoallylic acylhydrazines.
Scheme 17: Synthesis of trifluoromethylated cyanohydrazines and 3-trifluoromethyl-1,2,4-triazolines.
Scheme 18: N-Arylation and N-alkylation of trifluoromethyl acylhydrazones.
Scheme 19: [3 + 2]-Cycladditions of trifluoromethyl acylhydrazones.
Unprecedented synthesis of a 14-membered hexaazamacrocycle
- Anastasia A. Fesenko and
- Anatoly D. Shutalev
Beilstein J. Org. Chem. 2023, 19, 1728–1740, doi:10.3762/bjoc.19.126
- agents for magnetic resonance imaging, radiopharmaceuticals, sensors, NMR shift reagents, luminescent materials, catalysis, etc. To date, a large variety of PAMs with various ring sizes, number and location of nitrogen atoms, levels of unsaturation, etc. have been prepared and studied. Nevertheless, the
Graphical Abstract
Scheme 1: Synthesis of the key intermediate of the macrocycle preparation, 3-[(ethoxymethylene)amino]-1-methy...
Scheme 2: Synthesis of macrocycle 5 by the reaction of imidate 4 with hydrazine hydrate.
Scheme 3: Plausible pathway for the transformation of imidate 4 into macrocycle 5.
Scheme 4: Synthesis of pyrazolopyrimidine 8 by the reaction of imidate 4 with hydrazine hydrate.
Scheme 5: Synthesis of macrocycle 5 by the dimerization of pyrazolopyrimidine 8.
Scheme 6: Plausible pathway for the dimerization of pyrazolopyrimidine 8 into macrocycle 5.
Figure 1: Gibbs free energy diagram (B3LYP/6-311++G(d,p)) for the N2H4-promoted transformation of pyrazolopyr...
Scheme 7: Transformation of macrocycle 5 into pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine 13 and pyrazolo...
Quinoxaline derivatives as attractive electron-transporting materials
- Zeeshan Abid,
- Liaqat Ali,
- Sughra Gulzar,
- Faiza Wahad,
- Raja Shahid Ashraf and
- Christian B. Nielsen
Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124
- devices is discussed in detail. Additionally, their significance as thermally activated delayed fluorescence emitters and chromophores for OLEDs, sensors and electrochromic devices is explored. The review emphasizes the remarkable characteristics and versatility of quinoxaline derivatives in electron
- chromophores in the development of organic light-emitting diodes (OLEDs), sensors, and electrochromic devices [8][13][14]. In this review, we have comprehensively examined the recent advancements of Qx-derived ETMs in various applications within the organic semiconductor device field over the past five to six
- electronic characteristics. To enhance their performance in sensors and electrochromic devices, researchers have concentrated on manipulating their electron transport properties. By tailoring the strength of electron acceptors, fine-tuning the electronic nature of functional groups, incorporating additional
Graphical Abstract
Figure 1: Structures of some of the most versatile Qx scaffolds; dashed lines indicate the substitution sites...
Figure 2: Qx-derived polymer acceptors.
Figure 3: Qx-derived small molecule NFAs.
Figure 4: Qx-derived small molecule NFAs.
Figure 5: Dyes and sensitizers based on Qx auxiliary acceptors or bridging units.
Figure 6: Qx-derived n-type transistor materials.
Figure 7: Qx-derived ETM and TADF emitters.
Figure 8: Qx-derived chromophores.
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
- the possible future directions. Keywords: crown ethers; porphyrinoids; self-assembly; sensors; supramolecular chemistry; Introduction Many areas of modern supramolecular chemistry, organic, inorganic, materials and coordination chemistry, are based upon macrocyclic compounds of specifically-designed
- porphyrins as multitopic receptors, sensors, and supramolecular hosts, with applications in ion transport, catalysis, and polymeric materials [22][40][41][42][43][44][45]. In 1984 Lehn, Sessler and co-workers developed double-side-strapped crowned porphyrins, which served as tritopic and tetratopic receptors
- ether systems, where the catechol unit of the crown ether was fused to two β-pyrrolic positions of the porphyrin periphery. The systems presented intriguing intramolecular electron-transfer properties. Additionally, they were investigated as fluorescent sensors for various organic and metal cations [51
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.
Organic thermally activated delayed fluorescence material with strained benzoguanidine donor
- Alexander C. Brannan,
- Elvie F. P. Beaumont,
- Nguyen Le Phuoc,
- George F. S. Whitehead,
- Mikko Linnolahti and
- Alexander S. Romanov
Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95
- fluorescence [1][2][3]. Organic TADF emitters have gained substantial attention in recent years for their prospective application in organic light-emitting diodes (OLEDs), photocatalysis, bioimaging, and sensors [4][5][6]. The ability to harvest both singlet and triplet excitons enable organic TADF emitters to
Graphical Abstract
Figure 1: The molecular structures of the title compound 4BGIPN and the benchmark TADF emitter 4CzIPN.
Figure 2: Crystal structure for compound 4BGIPN in monoclinic form ((a) top view and (b) side view) where bla...
Figure 3: Full range cyclic voltammogram for 4BGIPN. Recorded using a glassy carbon electrode in THF solution...
Figure 4: UV–vis absorption spectra for compound 4BGIPN in various solvents.
Figure 5: Photoluminescence spectra for 4BGIPN at 295 and 77 K in (top left) MCH solution; (bottom left) Zeon...
Figure 6: Energy state diagram and natural transition orbitals HONTO and LUNTO for compound 4BGIPN in excited...
CuAAC-inspired synthesis of 1,2,3-triazole-bridged porphyrin conjugates: an overview
- Dileep Kumar Singh
Beilstein J. Org. Chem. 2023, 19, 349–379, doi:10.3762/bjoc.19.29
- well as optical properties. Moreover, the versatility of coumarin hybrids finds numerous applications including fluorescent brightening agents [16], optical sensors [17], organic light emitting diodes [18][19], light harvesting materials [20] and fluorescent probes in biological imaging [21]. Therefore
Graphical Abstract
Figure 1: Alkyne–azide "click reaction".
Figure 2: β- and meso-triazole-linked porphyrin.
Scheme 1: Synthesis of β-triazole-linked porphyrins 3a–c.
Scheme 2: Synthesis of β-triazole-bridged porphyrin-coumarin conjugates 11–20.
Scheme 3: Synthesis of β-triazole-bridged porphyrin-xanthone conjugates 23–27 and xanthone-bridged β-triazolo...
Scheme 4: Synthesis of meso-triazoloporphyrins 32a–c and triazole-bridged diporphyrins 34.
Scheme 5: Synthesis of meso-triazole-linked porphyrin-ferrocene conjugates 37a–d.
Scheme 6: Synthesis of meso-triazole-linked porphyrin conjugates 40a,b and 41a,b.
Scheme 7: Synthesis of meso-triazole-linked glycoporphyrins 43a–c.
Scheme 8: Synthesis of meso-triazole-linked porphyrin-coumarin conjugates 44–48.
Scheme 9: Synthesis of meso-triazole-bridged porphyrin-DNA conjugate 50.
Scheme 10: Synthesis of meso-linked porphyrin-triazole conjugates 53 and 57.
Scheme 11: Synthesis of meso-triazole-linked porphyrin-corrole conjugate 60.
Scheme 12: Synthesis of porphyrin conjugates 64a,b and 67a,b. Reaction conditions: (i) CuSO4, sodium ascorbate...
Scheme 13: Synthesis of meso-triazole-bridged porphyrin-quinolone conjugates 70a–e.
Scheme 14: Synthesis of meso-triazole-linked porphyrin-fluorescein dyad 73.
Scheme 15: Synthesis of meso-triazole-linked porphyrin-carborane conjugates 76a,b.
Scheme 16: Synthesis of meso-triazole-bridged porphyrin-BODIPY conjugates 78 and 80.
Scheme 17: Synthesis of meso-triazole-linked cationic porphyrin conjugates 85 and 87. Reaction conditions: (i)...
Scheme 18: Synthesis of meso-triazole-cobalt-porphyrin diimine-dioxime conjugate 91. Reactions conditions: (i)...
Scheme 19: Synthesis of triazole-linked porphyrin-bearing N-doped graphene hybrid 96.
Scheme 20: Synthesis of meso-triazole-linked porphyrin-fullerene dyads 100a–d and 104a,b.
Scheme 21: Synthesis of meso-triazole-bridged diporphyrin conjugates 107 and 108.
Scheme 22: Synthesis of porphyrin-ruthenium (II) conjugates 112a,b and 116a,b. Reaction conditions: (i) Zn(OAc)...
Scheme 23: Synthesis of meso-triazole-linked porphyrin dyad 119 and triad 121.
Scheme 24: Synthesis of di-triazole-bridged porphyrin-β-CD conjugate 126.
Scheme 25: Synthesis of meso-triazole-bridged porphyrin star trimer 129.
Scheme 26: Synthesis of 1,2,3-triazole-linked porphyrin-β-CD conjugates 131a,b.
Scheme 27: Synthesis of tritriazole-bridged porphyrin-lantern-DNA sequence 134.
Scheme 28: Synthesis of meso-triazole-linked porphyrin-polymer conjugates 137 and 139.
Scheme 29: Synthesis of triazole-linked capped porphyrin 142; Reaction conditions: method A: 10% H2O in THF, C...
Scheme 30: Synthesis of meso-tetratriazole-linked porphyrin-maleimine conjugates 145a–c.
Scheme 31: Synthesis of meso-tetratriazole-linked porphyrin-cholic acid complex 148a,b.
Scheme 32: Synthesis of meso-tetratriazole-linked porphyrin conjugates 151–153.
Scheme 33: Synthesis of meso-tetratrizole-porphyrin-carborane conjugates 155, 156 and 158a–c.
Scheme 34: Synthesis of meso-tetratriazole-porphyrin-cardanol conjugates 160 and 162.
Scheme 35: Synthesis of meso-tetratriazole-linked porphyrin-BODIPY conjugate 164.
Scheme 36: Synthesis of meso-tetratriazole-linked porphyrin-β-CD conjugates 166a,b.
Scheme 37: Synthesis of tetratriazole-bridged meso-arylporphyrins 171a–c and 172a–c.
Scheme 38: Synthesis of octatriazole-bridged porphyrin-β-CD conjugate 174 and porphyrin-adamantane conjugates ...
A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups
- Naser-Abdul Yousefi,
- Morten L. Zimmermann and
- Mikael Bols
Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165
- substances such as pharmaceuticals or fragrances is exploited since it is cheap, harmless and biodegradable [4]. It is also a useful building block for sensors and/or capture devices, advanced materials, and even artificial enzymes. Most such uses require that compound 1 can be chemically modified so that
Graphical Abstract
Figure 1: Structure of α-cyclodextrins 1–10.
Scheme 1: The reaction of perbenzylated α-cyclodextrin with iBu2AlH.
1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes
- Artem N. Semakin,
- Ivan S. Golovanov,
- Yulia V. Nelyubina and
- Alexey Yu. Sukhorukov
Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148
- Tripodal molecules are widely used as chelating ligands for transition metal catalysis [1][2][3], sensors for ions and small molecules [4][5], reagents for surface grafting [6], building blocks for the construction of supramolecular structures [7], polycyclic cage molecules [8], and porous materials [9
Graphical Abstract
Figure 1: Adamantane-based tripodal scaffolds and current work.
Scheme 1: A general strategy for the assembly of TAAD derivatives.
Scheme 2: Synthesis of acyclic precursors to 3N-TAADs, 2N,1O-TAADs, and 1N,2O-TAADs.
Scheme 3: Synthesis of 3N-TAADs, 2N,1O-TAADs, and 1N,2O-TAADs. *Yield based on compound 14.
Scheme 4: Deprotection of TAAD 8b and subsequent complexation with phenylboronic acid.
Scheme 5: Quaternization of TAADs 4c, 4e, 6a, and 8a followed by deprotection of N-Boc groups.
Figure 2: General view of the 1,4,6,10-tetraazaadamantane motif in X-ray structures of the obtained N-TAAD de...
Figure 3: (a) General structure of host–guest complexes of 3N-TAADs with water. (b) The general structure of ...
Figure 4: (a) Dynamic processes in TAADs 4 and complexation with ROH. (b) Fragment of 1H NMR spectra of Bn-4c...
Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation
- Ashish Kumar Mazumdar,
- Gyana Prakash Nanda,
- Nisha Yadav,
- Upasana Deori,
- Upasha Acharyya,
- Bahadur Sk and
- Pachaiyappan Rajamalli
Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122
- detecting organic acid vapor at ambient conditions is challenging for solid-state detectors. Therefore, developing a solid-state emitter with reversible switching of the optical properties by external stimuli, such as acid and base vapors, is important. As per the recent literature, such sensors are being
- disruption of the molecular conjugation or ICT interactions upon protonation or deprotonation would lead to switching of the optical properties. While there are many reports on acid–based sensors, TADF emitter-based sensors are rare in the literature. In this context, we chose the D–A molecular design to
Graphical Abstract
Scheme 1: Synthetic schemes of BPy-pTC and BPy-p3C.
Figure 1: (a) Normalized absorption spectra of BPy-pTC and BPy-p3C in toluene at room temperature; (b) normal...
Figure 2: Transient photoluminescence decay (λex = 375 nm) of (a) BPy-pTC and (b) BPy-p3C in degassed THF (10...
Figure 3: AIEE studies: Emission spectra (λex = 375 nm, 10 µM) of (a) BPy-pTC and (d) BPy-p3C in THF with inc...
Figure 4: Normalized fluorescence at room temperature and phosphorescence spectra at 77 K (λex = 375 nm, 10 µ...
Figure 5: Transient photoluminescence decay (λex = 375 nm, 20 µM) of (a) BPy-pTC and (b) BPy-p3C aggregates i...
Figure 6: Fluorescence switching by acid and base fumes exposure: Emission spectra (λex = 375 nm) of (a) BPy-p...
Figure 7: Fluorescence intensity vs number of exposures for (a) BPy-p3C and (b) BPy-pTC thin films upon expos...
Synthesis, optical and electrochemical properties of (D–π)2-type and (D–π)2Ph-type fluorescent dyes
- Kosuke Takemura,
- Kazuki Ohira,
- Taiki Higashino,
- Keiichi Imato and
- Yousuke Ooyama
Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106
- ][16][17][18][19][20][21][22], as well as fluorescent probes [23][24][25][26][27][28] for bioimaging and fluorescent sensors for specific target species [29][30][31][32]. Among many kinds of organic fluorescent dyes, much efforts have been made on the development of donor–π–acceptor (D–π–A)-type
Graphical Abstract
Scheme 1: Synthesis of OTK-2 and OTT-2.
Figure 1: (a) Photoabsorption and (b) fluorescence (λex = λmax,abs) spectra of OTK-2 [33] and OTT-2 in toluene. (...
Figure 2: Cyclic voltammograms of OTK-2 and OTT-2 (0.1 mM) in DMF containing 0.1 M Bu4NClO4 at a scan rate of...
Figure 3: (a) HOMO and (b) LUMO of OTK-2 [33] and OTT-2 derived from MO calculations (PM5, INDO/S method). The re...
Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties
- Masayori Hagimori,
- Tatsusada Yoshida,
- Yasuhisa Nishimura,
- Yukiko Ogawa and
- Keitaro Tanaka
Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60
- have been reported [7][8][9][10]. Because the aggregated state of AIEE-based compounds is affected by the external environment, these compounds have found use in clinical applications as chemical sensors or fluorescent probes [7][8][9][10]. Pyridine is a nitrogen-containing heterocyclic compound found
Graphical Abstract
Scheme 1: Syntheses of pyrido[1,2-a]pyrrolo[3,4-d]pyrimidine 3a and N-methyl-4-((5-bromopyridin-2-yl)amino)-s...
Figure 1: Presumed reaction mechanism to produce 3a.
Figure 2: Fluorescence spectral profiles of (a) 4a (10−5 M, Exmax = 413 nm) and (b) 4e (10−5 M, Exmax = 415 n...
Figure 3: Fluorescence spectral changes of (a) 4a (10−5 M, Exmax = 413 nm) and (b) 4e (10−5 M, Exmax = 415 nm...
Figure 4: Protonation of N-methyl-4-((pyridin-2-yl)amino)-substituted maleimides 4 by 0.1 M HCl.
Figure 5: Frontier molecular orbitals and HOMO–LUMO energy gaps of compounds 3a, 4a, and 4e for ground-state ...
Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity
- Anna V. Korotina,
- Svetlana G. Tolshchina,
- Rashida I. Ishmetova,
- Natalya P. Evstigneeva,
- Natalya A. Gerasimova,
- Natalya V. Zilberberg,
- Nikolay V. Kungurov,
- Gennady L. Rusinov,
- Oleg N. Chupakhin and
- Valery N. Charushin
Beilstein J. Org. Chem. 2022, 18, 243–250, doi:10.3762/bjoc.18.29
- as high-energy materials [23][24][25], molecules with promising photophysical, electrochemical and coordination properties for use in sensors, OLEDs, semiconductor materials, etc. [26][27][28]. The most important biomedical application of 1,2,4,5-tetrazines are bioorthogonal reactions that allow
Graphical Abstract
Scheme 1: Chemical structures of [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine (a), [1,2,4]triazolo[1,5-b][1,2,4,5...
Scheme 2: Synthesis of [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines 3a–k.
Figure 1: X-ray structure of N-(6-(4-bromo-3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazin-3-yl)benzamide.
Scheme 3: Reactions of triazolo[1,5-b][1,2,4,5]tetrazines 3a,j with N- and O-nucleophiles.
Scheme 4: Reactions of triazolo[1,5-b][1,2,4,5]tetrazines 3a,j with C-nucleophiles.
Scheme 5: Reactions of 6-(3,5-dimethyl-1H-pyrazol-1-yl)-3-methyl-[1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine (10a...
1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis
- Ruan Carlos B. Ribeiro,
- Patricia G. Ferreira,
- Amanda de A. Borges,
- Luana da S. M. Forezi,
- Fernando de Carvalho da Silva and
- Vitor F. Ferreira
Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5
- , pharmaceutical, and biological sciences. A lot of the literature in this area is quite old. Perhaps there are also opportunities in this area to apply modern chemistry methodology, and also in the development of more sophisticated sensors and dyes. Naphthoquinones are commonly used in organic synthesis. Some
Graphical Abstract
Figure 1: Naphthoquinones are commonly used in organic synthesis.
Figure 2: Some important natural and synthetic naphthoquinones.
Scheme 1: Synthetic studies of BNQs and reactions with amines.
Scheme 2: Methods described for the synthesis of β-NQS.
Figure 3: Drugs detected using β-NQSNa.
Scheme 3: Reactions between β-NQS and amines.
Scheme 4: Isomerization of 4-arylamino-1,2-naphthoquinones.
Scheme 5: Synthesis of unsymmetrical 2-amino-4-imino compounds.
Scheme 6: Synthesis of bis(isoxazolyl)naphthoquinones from β-NQS.
Scheme 7: The reaction of β-NQS with 30 followed by cycle condensation.
Scheme 8: Synthesis of 4-(2-amino-5-selenothiazoles)-1,2-naphthoquinones.
Scheme 9: Synthesis of amino- and phenoxy-1,2-naphthoquinones.
Scheme 10: Synthesis of 4-semicarbazide-1,2-naphthoquinone.
Scheme 11: Reactions of 4-azido-1,2-naphthoquinone.
Figure 4: Modifications that can be easily carried out from the products of β-NQS 8.
Scheme 12: Derivatives of 1,2-naphthoquinones obtained from β-NQS.
Scheme 13: Oximes as well as 4-amino- and 4-phenoxy-1,2-naphthoquinone as potential anti-inflammatory agents.
Scheme 14: Synthesis of triazoles from β-NQS.
Scheme 15: Synthesis of naphtho[1,2-d]oxazoles from β-NQS.
Scheme 16: A) Arylation and vinylation of β-NQS catalyzed by Ni(II) salts. B) Transformation of the 1,2-dicarb...
Scheme 17: Benzo[a]carbazole and benzo[c]carbazoles fused with 1,2-naphthoquinone.
Scheme 18: Synthesis of 1,2-naphthoquinones having a C=C bond from β-NQS. Method A: NaOH, EtOH/H2O, 40 °C, 2 h...
Scheme 19: C=C bond formation from β-NQS and substituted acetonitriles.
Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing
- Luke O. Jones,
- Leah Williams,
- Tasmin Boam,
- Martin Kalmet,
- Chidubem Oguike and
- Fiona L. Hatton
Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171
- cell proliferation and waste exchange, e.g., in a scaffold for tissue engineering applications [3]. Novel biomedical and biotechnical applications of cryogels can also be found in controlled drug delivery, carriers for cell immobilization, sensors, bioseparation, purification, and wound dressing [4][5
Graphical Abstract
Figure 1: Schematic representation of the process of aqueous cryogel formation, using (a) monomers/small mole...
Figure 2: Microarchitecture of gelatin cryogels. (A) Surface and cross-sectional SEM micrographs of highly po...
Figure 3: Principle of 3D-cryogel printing. A) Illustration of 3D-printing of cryogels. B) Illustration of th...
Figure 4: Illustration of the production of the injectable multifunctional composite, comprised of alginate c...
Figure 5: Digital and SEM photographs of PETEGA cryogel at 20 °C (top) and 50 °C (bottom), synthesised via UV...
Figure 6: Cell morphology of T47D breast cancer cells cultured in HA cryogels. (A) Schematic representation o...
Figure 7: Preparation of PDMA/β-CD cryogel via cryogenic treatment and photochemical crosslinking in frozen s...
Figure 8: (A) Healing rate of wounds treated with autoclaved CG11 cryogels and those treated with 70% ethanol...
Figure 9: In vivo haemostatic capacity evaluation of the cryogels. Blood loss (a) and haemostatic time (b) in...
Constrained thermoresponsive polymers – new insights into fundamentals and applications
- Patricia Flemming,
- Alexander S. Münch,
- Andreas Fery and
- Petra Uhlmann
Beilstein J. Org. Chem. 2021, 17, 2123–2163, doi:10.3762/bjoc.17.138
- , have been intensively studied in solution. For the application of such polymers in novel sensors, drug delivery systems or as multifunctional coatings, they typically have to be transferred into specific arrangements, such as micelles, polymer films or grafted nanoparticles. However, it turns out that
- including biomedicine [29][30], drug delivery [12][31], tissue engineering [32][33], analytic application [18], environmental applications [34][35], sensors [36][37][38], actuators [37][38][39] and other applications [5]. For many of these purposes, it is essential to tether such polymers to interfaces or
Graphical Abstract
Figure 1: (a) Schematic representation of the phase stability of a binary mixture based on the free enthalpy ...
Figure 2: Illustration of the relationship between the type of miscibility gap and the temperature dependence...
Figure 3: Schematically pictured phase diagram of a binary mixture composed of a dissolved polymer with a LCS...
Figure 4: Schematic illustration of a thermo-induced swelling behavior of a star polymer composed of responsi...
Figure 5: Schematic illustration of self-assembly of block copolymer amphiphiles in a polar medium.
Figure 6: Schematic comparison of the size and conformation between free polymer chains (a), grafted polymer ...
Figure 7: Comparison of the possible phase diagrams of a polymer in solution with partially miscibility and t...
Figure 8: Selection of polymers exhibiting UCST behavior due to hydrogen bonding (blue) divided into homo- (a...
Figure 9: Part A shows the molecular structure of PDMAPS stars synthesized by Li et al. (left) demonstrating ...
Figure 10: Part A contains a schematic demonstration of conformational transitions of dual-thermoresponsive bl...
Figure 11: Part A pictures zwitterionic brushes grafted from silicon substrates obtaining a nonassociated, hyd...
Figure 12: Part A pictures the UCST phase transition of zwitterionic polymers grafted on the surface of mesopo...
Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications
- Nikita Brodyagin,
- Martins Katkevics,
- Venubabu Kotikam,
- Christopher A. Ryan and
- Eriks Rozners
Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116
Graphical Abstract
Figure 1: Structure of DNA and PNA.
Figure 2: PNA binding modes: (A) PNA–dsDNA 1:1 triplex; (B) PNA–DNA–PNA strand-invasion triplex; (C) the Hoog...
Figure 3: Structure of P-form PNA–DNA–PNA triplex from reference [41]. (A) view in the major groove and (B) view ...
Figure 4: Structures of backbone-modified PNA.
Figure 5: Structures of PNA having α- and γ-substituted backbones.
Figure 6: Structures of modified nucleobases in PNA to improve Hoogsteen hydrogen bonding to guanine and aden...
Figure 7: Proposed hydrogen bonding schemes for modified PNA nucleobases designed to recognize pyrimidines or...
Figure 8: Modified nucleobases to modulate Watson–Crick base pairing and chemically reactive crosslinking PNA...
Figure 9: Examples of triplets formed by Janus-wedge PNA nucleobases (blue). R1 denotes DNA, RNA, or PNA back...
Figure 10: Examples of fluorescent PNA nucleobases. R1 denotes DNA, RNA, or PNA backbones.
Figure 11: Endosomal entrapment and escape pathways of PNA and PNA conjugates.
Figure 12: (A) representative cell-penetrating peptides (CPPs), (B) conjugation designs and linker chemistries....
Figure 13: Proposed delivery mode by pHLIP-PNA conjugates (A) the transmembrane section of pHLIP interacting w...
Figure 14: Structures of modified penetratin CPP conjugates with PNA linked through either disulfide (for stud...
Figure 15: Chemical structure of C9–PNA, a stable amphipathic (cyclic-peptide)–PNA conjugate.
Figure 16: Structures of PNA conjugates with a lipophilic triphenylphosphonium cation (TPP–PNA) through (A) th...
Figure 17: Structures of (A) chloesteryl–PNA, (B) cholate–PNA and (C) cholate–PNA(cholate)3.
Figure 18: Structures of PNA–GalNAc conjugates (A) (GalNAc)2K, (B) triantennary (GalNAc)3, and (C) trivalent (...
Figure 19: Vitamin B12–PNA conjugates with different linkages.
Figure 20: Structures of (A) neomycin B, (B) PNA–neamine conjugate, and (C) PNA–neosamine conjugate.
Figure 21: PNA clamp (red) binding to target DNA containing a mixture of sequences (A) PNA binds with higher a...
Figure 22: Rolling circle amplification using PNA openers (red) to invade a dsDNA target forming a P-loop. A p...
Figure 23: Molecular beacons containing generic fluorophores (Fl) and quenchers (Q) recognizing a complementar...
Figure 24: (A) Light-up fluorophores such as thiazole orange display fluorescence enhancement upon binding to ...
Figure 25: Templated fluorogenic detection of oligonucleotides using two PNAs. (A) Templated FRET depends on h...
Figure 26: Lateral flow devices use a streptavidin labeled strip on nitrocellulose paper to anchor a capture P...
Recent advances in the application of isoindigo derivatives in materials chemistry
- Andrei V. Bogdanov and
- Vladimir F. Mironov
Beilstein J. Org. Chem. 2021, 17, 1533–1564, doi:10.3762/bjoc.17.111
- of functional materials are analyzed and summarized. These bisheterocycles can be used in the creation of organic solar cells, sensors, lithium ion batteries as well as in OFET and OLED technologies. The potentials of the use of polymer structures based on isoindigo as photoactive component in the
- towards n-butanol. The lower limit of detection was 100 ppm with a response time of less than 10 s. The ability of polymeric isoindigo derivatives to strongly bind to carbon nanotubes due to π-stacking was used to create sensors for the determination of NO2 in the gaseous state (see polymer 61) and
- polymers for OFETs. Isoindigoid homopolymers with differing rigidity. Isoindigo-based materials with extended π-conjugation. Poly(isoindigothiophene) compounds as sensors for ammonia. Sensor devices based on poly(isoindigoaryl) compounds. Isoindigo polymers for miscellaneous applications. Mono-, rod-like
Graphical Abstract
Scheme 1: Representatives of isomeric bisoxindoles.
Scheme 2: Isoindigo-based OSCs with the best efficiency.
Scheme 3: Monoisoindigos with preferred 6,6'-substitution.
Scheme 4: Possibility of aromatic–quinoid structural transition.
Scheme 5: Isoindigo structures with incorporated acceptor nitrogen heterocycles.
Scheme 6: Monoisoindigos bearing pyrenyl substituents.
Scheme 7: p-Alkoxyphenylene-embedded thienylisoindigo with different acceptor anchor units.
Scheme 8: Nonfullerene OSC based on perylene diimide-derived isoindigo.
Scheme 9: Isoindigo as an additive in all-polymer OSCs.
Scheme 10: Bisisoindigos with different linker structures.
Scheme 11: Nonthiophene oligomeric monoisoindigos for OSCs.
Scheme 12: The simplest examples of polymers with a monothienylisoindigo monomeric unit.
Scheme 13: Monothienylisoindigos bearing π-extended electron-donor backbones.
Scheme 14: Role of fluorination and the molecular weight on OSC efficiency on the base of the bithiopheneisoin...
Scheme 15: Trithiopheneisoindigo polymers with variation in the substituent structure.
Scheme 16: Polymeric thienyl-linked bisisoindigos for OSCs.
Scheme 17: Isoindigo bearing the thieno[3,2-b]thiophene structural motif as donor component of OSCs.
Scheme 18: Thienylisoindigos with incorporated aromatic unit.
Scheme 19: One-component nonfullerene OSCs on the base of isoindigo.
Scheme 20: Isoindigo-based nonthiophene aza aromatic polymers as acceptor components of OSCs.
Scheme 21: Polymers with isoindigo substituent as side-chain photon trap.
Scheme 22: Isoindigo derivatives for OFET technology with the best mobility.
Scheme 23: Monoisoindigos as low-molecular-weight semiconductors.
Scheme 24: Polymeric bithiopheneisoindigos for OFET creation.
Scheme 25: Fluorination as a tool to improve isoindigo-based OFET devices.
Scheme 26: Diversely DPP–isoindigo-conjugated polymers for OFETs.
Scheme 27: Isoindigoid homopolymers with differing rigidity.
Scheme 28: Isoindigo-based materials with extended π-conjugation.
Scheme 29: Poly(isoindigothiophene) compounds as sensors for ammonia.
Scheme 30: Sensor devices based on poly(isoindigoaryl) compounds.
Scheme 31: Isoindigo polymers for miscellaneous applications.
Scheme 32: Mono-, rod-like, and polymeric isoindigos as agents for photoacoustic and photothermal cancer thera...
Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96
- macrocycles [31][32]. Moreover, polypyrrolic systems are of extensive interest in numerous areas namely optics, medicine, and supramolecular chemistry in addition to the materials sciences and technology. Fascinatingly, in luminescence as well as fluorescence-based sensors, pyrrole derivatives play a vital
Graphical Abstract
Scheme 1: Retrosynthetic pathways to the pyrrole-based C3-symmetric truxene derivative 6.
Scheme 2: Synthesis of tripyrrolotruxene 6 via cyclotrimerization and RCM as crucial steps.
Scheme 3: Synthesis of star-shaped molecule 6 utilizing the Clauson–Kaas pyrrole strategy.
Scheme 4: Synthesis of truxene derivative 6 involving Ullmann-type cross-coupling reaction.
Scheme 5: Synthesis of imidazole and benzimidazole containing truxene derivatives 14 and 16.
Scheme 6: Construction of truxene-based di- and trioxazole derivatives 21 and 20.
Scheme 7: Synthesis of benzene-bridged rings containing trioxazolotruxene system 25.
Figure 1: Normalized absorption (left); fluorescence spectra (right) of the synthesized truxene derivatives (...
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
- monitoring features such as pressure sensors that can both detect, assess, and if necessary, invoke emergency venting or diversion of material to auxiliary depressurisation stages, often without needing a full reactor shut down. There are numerous examples within the literature in which a flow synthesis has
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications
- Christopher Liczner,
- Kieran Duke,
- Gabrielle Juneau,
- Martin Egli and
- Christopher J. Wilds
Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76
Graphical Abstract
Figure 1: Structures of the chemically modified oligonucleotides (A) N3' → P5' phosphoramidate linkage, (B) a...
Scheme 1: Synthesis of a N3' → P5' phosphoramidate linkage by solid-phase synthesis. (a) dichloroacetic acid;...
Figure 2: Crystal structures of (A) N3' → P5' phosphoramidate DNA (PDB ID 363D) [71] and (B) amide (AM1) RNA in c...
Scheme 2: Synthesis of a phosphorodithioate linkage by solid-phase synthesis. (a) detritylation; (b) tetrazol...
Figure 3: Close-up view of a key interaction between the PS2-modified antithrombin RNA aptamer and thrombin i...
Scheme 3: Synthesis of the (S)-GNA thymine phosphoramidite from (S)-glycidyl 4,4'-dimethoxytrityl ether. (a) ...
Figure 4: Surface models of the crystal structures of RNA dodecamers with single (A) (S)-GNA-T (PDB ID 5V1L) [54]...
Figure 5: Structures of 2'-O-alkyl modifications. (A) 2'-O-methoxy RNA (2'-OMe RNA), (B) 2'-O-(2-methoxyethyl...
Scheme 4: Synthesis of the 2'-OMe uridine from 3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)uridine. (a) Benzoy...
Scheme 5: Synthesis of the 2'-O-MOE uridine from uridine. (a) (PhO)2CO, NaHCO3, DMA, 100 °C; (b) Al(OCH2CH2OCH...
Figure 6: Structure of 2'-O-(2-methoxyethyl)-RNA (MOE-RNA). (A) View into the minor groove of an A-form DNA d...
Figure 7: Structures of locked nucleic acids (LNA)/bridged nucleic acids (BNA) modifications. (A) LNA/BNA, (B...
Scheme 6: Synthesis of the uridine LNA phosphoramidite. (a) i) NaH, BnBr, DMF, ii) acetic anhydride, pyridine...
Scheme 7: Synthesis of the 2'-fluoroarabinothymidine. (a) 30% HBr in acetic acid; (b) 2,4-bis-O-(trimethylsil...
Figure 8: Sugar puckers of arabinose (ANA) and arabinofluoro (FANA) nucleic acids compared with the puckers o...
Figure 9: Structures of C4'-modified nucleic acids. (A) 4'-methoxy, (B) 4'-(2-methoxyethoxy), (C) 2',4'-diflu...
Scheme 8: Synthesis of the 4'-F-rU phosphoramidite. (a) AgF, I2, dichloromethane, tetrahydrofuran; (b) NH3, m...
Scheme 9: Synthesis of the thymine FHNA phosphoramidite. (a) thymine, 1,8-diazabicyclo[5.4.0]undec-7-ene, ace...
Scheme 10: Synthesis of the thymine Ara-FHNA phosphoramidite. (a) i) trifluoromethanesulfonic anhydride, pyrid...
Figure 10: Crystal structures of (A) FHNA and (B) Ara-FHNA in modified A-form DNA decamers (PDB IDs 3Q61 and 3...
1,2,3-Triazoles as leaving groups: SNAr reactions of 2,6-bistriazolylpurines with O- and C-nucleophiles
- Dace Cīrule,
- Irina Novosjolova,
- Ērika Bizdēna and
- Māris Turks
Beilstein J. Org. Chem. 2021, 17, 410–419, doi:10.3762/bjoc.17.37
- ][68][69] and can be used as metal ion sensors [70]. Therefore, it is important to develop novel methods towards this type of derivatives. To date two approaches have been used to obtain 6-substituted 2-triazolylpurine derivatives (Scheme 1). According to the pathway A, firstly a selected substituent
Graphical Abstract
Scheme 1: Synthetic pathways for the synthesis of 6-substituted 2-triazolylpurine derivatives IV.
Scheme 2: Synthesis of 2,6-bistriazolylpurine derivatives 2a–c.
Scheme 3: Synthesis of 6-alkyloxy-2-triazolylpurine derivatives 3a–f.
Scheme 4: Synthesis of 6-alkyloxy-2-triazolylpurine nucleosides 3g–j.
Scheme 5: 2,6-Bistriazolylpurine derivatives in SNAr reactions with H2O/HO− as nucleophiles.
Scheme 6: Synthesis of C6-substituted 2-triazolylpurine derivatives 5.
Figure 1: Possible tautomeric structures of compounds 5a–d.
19F NMR as a tool in chemical biology
- Diana Gimenez,
- Aoife Phelan,
- Cormac D. Murphy and
- Steven L. Cobb
Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28
Graphical Abstract
Figure 1: Selected examples of 19F-labelled amino acid analogues used as probes in chemical biology.
Figure 2: (a) Sequences of the antimicrobial peptide MSI-78 and pFtBSer-containing analogs and cartoon repres...
Figure 3: (a) Chemical structures of a selection of trifluoromethyl tags. (b) Comparative analysis showing th...
Figure 4: (a) First bromodomain of Brd4 with all three tryptophan residues displayed in blue and labelled by ...
Figure 5: (a) Enzymatic hydroxylation of GBBNF in the presence of hBBOX (b) 19F NMR spectra showing the conve...
Figure 6: (a) In-cell enzymatic hydrolysis of the fluorinated anandamide analogue ARN1203 catalyzed by hFAAH....
Figure 7: (a) X-ray crystal structure of CAM highlighting the location the phenylalanine residues replaced by...
Figure 8: 19F PREs of 4-F, 5-F, 6-F, 7-FTrp49 containing MTSL-modified S52CCV-N. The 19F NMR resonances of ox...
Figure 9: 19F NMR as a direct probe of Ud NS1A ED homodimerization. Schematic representation showing the loca...
Figure 10: (a) Representative spectrum of a 182 μM sample of Aβ1-40-tfM35 at varying times indicating the majo...
Figure 11: Illustration of the conformational switch induced by SDS in 4-tfmF-labelled α-Syn. Also shown are t...
Figure 12: (a) Structural models of the Myc‐Max (left), Myc‐Max‐DNA (middle) and Myc‐Max‐BRCA1 complexes (righ...
Figure 13: (a) Side (left) and bottom (right) views of the pentameric apo ELIC X-ray structure (PDB ID: 3RQU) ...
Figure 14: (a) General structure of a selection of recently developed 19F-labelled nucleotides for their use a...
Figure 15: Monitoring biotransformation of the fluorinated pesticide cyhalothrin by the fungus C. elegans. The...
Figure 16: Following the biodegradation of emerging fluorinated pollutants by 19F NMR. The spectra are from cu...
Figure 17: Discovery of new fluorinated natural products by 19F NMR. The spectrum is of the culture supernatan...
Figure 18: Application of 19F NMR to investigate the biosynthesis of nucleocidin. The spectra are from culture...
Figure 19: Detection of new fluorofengycins (indicated by arrows) in culture supernatants of Bacillus sp. CS93...
Figure 20: Measurement of β-galactosidase activity in MCF7 cancer cells expressing lacZ using 19F NMR. The deg...
Figure 21: Detection of ions using 19F NMR. (a) Structure of TF-BAPTA and its 19F iCEST spectra in the presenc...
Figure 22: (a) The ONOO−-mediated decarbonylation of 5-fluoroisatin and 6-fluoroisatin. The selectivity of (b)...
Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies
- Alexander Zika and
- Franziska Gröhn
Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17
- ; multiswitchable; photoacid; polyelectrolyte; Introduction Supramolecular nanoscale assemblies responding to multiple stimuli are highly desirable in various fields including transport systems, sensors, and optoelectronic applications [1][2][3][4][5][6][7][8]. Self-assembly into supramolecular structures and
Graphical Abstract
Scheme 1: The chemical network of reactions for 4-hydroxyflavylium (left) and the write-lock-erase cycle (rig...
Scheme 2: The building blocks used for the self-assembly in this study: pelargonidin chloride (Flavy), 1-naph...
Scheme 3: Overview of the different states of the multi-switchable system consisting of Flavy, 1N36S, and pol...
Figure 1: Top: pelargonidin cation (Flavy) and network of chemical reactions; bottom: corresponding UV–vis sp...
Figure 2: Characterization of Flavy: a) 1H NMR spectrum at pH 7.0 (form A) before and after irradiation; b) 13...
Scheme 4: Overview of the different states of the two main cycles switching the system consisting of 1N36S, F...
Figure 3: UV–vis spectroscopy of the ternary nano-assemblies for cycle I (a) and cycle II (b).
Figure 4: Dynamic light scattering: Electric field autocorrelation function g1(τ) and distribution of relaxat...
Figure 5: Static light scattering data from the assemblies of cycle I; a) A, non-irradiated, spherical partic...
Figure 6: Comparison of cycle I and cycle II in AFM.
Figure 7: a) ζ-Potential and b) effective surface charge density for cycle I; c) ζ-potential and d) effective...
Figure 8: Isothermal titration calorimetry of poly(allylamine) into the cell containing Flavy and 1N36S in aq...
Figure 9: Polar surface area of Flavy in form of A (left) and B (right).
Figure 10: Hydrodynamic radii of the nano-assemblies as function of the loading ratio: a) cycle I, b) cycle II....
Figure 11: UV–vis spectra of the nano-assemblies of cycle II at l = 0.75.
Figure 12: ζ-Potential of the nano-assemblies of cycle II depending on the concentration ratio.
Scheme 5: Different mixing orders of the assemblies. The major part of this study focuses on route i.
Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring
- Daria I. Tonkoglazova,
- Anna V. Gulevskaya,
- Konstantin A. Chistyakov and
- Olga I. Askalepova
Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2
- [31], chemical sensors [32], DNA-intercalators [33][34] etc. Besides typical carbohelicenes, heterohelicenes, incorporating one or more heteroaromatic units in the skeleton, have also gained increasing attention [1][2][3][4][5][6][7][8][9][10][11]. The presence of heteroatoms (S, N, O, P) in the fused
Graphical Abstract
Scheme 1: Overview of the synthetic methods for the carbazole-based heterohelicenes. i) Pd2dba3, xantphos, K3...
Scheme 2: Synthetic strategy for the carbazole-based [6]helicenes fused with an azine ring.
Scheme 3: Sonogashira coupling of compound 4b with phenylacetylene. i) Pd(PPh3)2Cl2, CuI, iPr2NH, DMSO, 80 °C...
Figure 1: Molecular structure of carbazole-based [6]helicenes 10a (a), 10b (b) and 10c (c) (X-ray data).
Figure 2: Crystal packing of carbazole-based [6]helicenes 10a (a, b), 10b (c,d) and 10c (e). Hydrogen atoms a...
Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation
- Tereza Horáčková,
- Jan Budka,
- Vaclav Eigner,
- Wen-Sheng Chung,
- Petra Cuřínová and
- Pavel Lhoták
Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249
- have gradually been revealed and are well recognised to date. Consequently, given the importance of anions in many areas of everyday life, including, e.g., biology, medicine, environmental pollution issues, or industrial processes, the design and development of novel artificial receptors/sensors for
Graphical Abstract
Figure 1: Design of chiral calix[4]arene-based receptors for anions.
Scheme 1: Synthesis of the calix[4]arene-based chiral anionic receptors 7 and 8.
Figure 2: X-ray structure of 4a: (a) Top view into the cavity. (b) Side view of the same cavity.
Figure 3: X-ray structure of 7a: (a) Hydrogen bonding interactions (black) in a dimeric motif, chalcogen inte...
Figure 4: X-ray structure of 7d, showing hydrogen bonds between the ureido units (green) and hydrogen bonding...
Figure 5: 1H NMR titration of 7c with N-acetyl-ᴅ-phenylalaninate and N-acetyl-ʟ-phenylalaninate (as TBA salts...
