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Search for "phenazine" in Full Text gives 18 result(s) in Beilstein Journal of Organic Chemistry.
HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines
- Luan A. Martinho and
- Carlos Kleber Z. Andrade
Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55
- green catalyst with greater chemical and thermal stability in comparison to other heteropolyacids [43]. HPW has been shown to catalyze MCRs in the synthesis of heterocyclic compounds with high efficiency and chemoselectivity (Figure 2), including functionalized benzo[c]chromeno[2,3-a]phenazine [44
Graphical Abstract
Figure 1: Selected examples of commercial drugs containing the imidazo[1,2-a]pyridine core [13].
Figure 2: Examples of application of HPW as catalyst in the synthesis of heterocyclic compounds through multi...
Scheme 1: a) Reported phosphomolybdic acid-catalyzed synthesis of imidazo[1,2-a]pyridines via GBB-3CR. b) Att...
Scheme 2: Substrate scope of the HPW-catalyzed GBB reactions using a range of aromatic/heteroaromatic aldehyd...
Scheme 3: Substrate scope of the HPW-catalyzed GBB reaction using aliphatic aldehydes. Reaction conditions: 2...
Scheme 4: Unsuccessful substrates for the HPW-catalyzed GBB-3CR for the synthesis of imidazo[1,2-a]pyridines.
Scheme 5: 10-Fold scale-up of the HPW-catalyzed GBB reaction (5.0 mmol) between 2-aminopyridine (1a), 4-nitro...
Scheme 6: Plausible reaction mechanism for the HPW-catalyzed GBB reaction.
Metal-catalyzed coupling/carbonylative cyclizations for accessing dibenzodiazepinones: an expedient route to clozapine and other drugs
- Amina Moutayakine and
- Anthony J. Burke
Beilstein J. Org. Chem. 2024, 20, 193–204, doi:10.3762/bjoc.20.19
- , failed to provide any improvement (entry 10, Table 2). However, replacing DMF by dioxane as the solvent in the presence of DBU led to a significant improvement in the yield of the reaction, as the intermediate 3a could be obtained in 40% yield, along with the phenazine 6 in 48% (entry 11, Table 2). Next
- , we screened other ligands such as XPhos and DPEPhos in the presence of Cs2CO3 as base in dioxane, however, the undesired phenazine product 6 was still obtained in moderate yield under these conditions (entries 12 and 13, Table 2). In the presence of SPhos as ligand, Cs2CO3, and toluene as solvent
- , the desired intermediate 3a was obtained in 20% yield along with 55% of the phenazine 6 (entry 14, Table 2). Although toluene was shown to be a good solvent for this B–H coupling reaction, we were unable to prevent the double B–H reaction from occurring leading to the phenazine 6, even when shortening
Graphical Abstract
Figure 1: Biologically active dibenzodiazepinones.
Scheme 1: Different synthetic routes to DBDAPs (a–c), including our novel approach (d).
Scheme 2: One-pot synthesis of 5H-dibenzo[b,e][1,4]diazepin-11-ol (5).
Scheme 3: Scope of the Chan–Lam coupling between o-phenylenediamines and 2-bromophenylboronic acids (please n...
Scheme 4: Scope of the synthesis of DBDAPs. Please note that product 4g contained some unidentified impuritie...
Scheme 5: Proposed mechanism.
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
- -based dyes, Qx39–Qx42 and the resulting device performance were highlighted by Huang et al. The use of quinoxaline-dithienothiophene and phenazine-dithienothiophene as π-bridges with the benzothiadiazole moiety as an auxiliary group did not yield the expected improvement, potentially due to the non
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.
Photoredox catalysis harvesting multiple photon or electrochemical energies
- Mattia Lepori,
- Simon Schmid and
- Joshua P. Barham
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
Graphical Abstract
Figure 1: Oxidative and reductive activations of organic compounds harvesting photoredox catalysis.
Figure 2: General catalytic cycles of radical ion conPET (left) and radical ion e-PRC (right).
Figure 3: “Beginner’s guide”: comparison between advantages, capacities, and prospectives of conPET and PEC.
Figure 4: A) conPET reductive dehalogenation of aryl halides with PDI. B) Reductive C–H arylation with pyrrol...
Figure 5: A) Chromoselective mono- and disubstitution or polybrominated pyrimidines with pyrroles. B) Sequent...
Figure 6: A) Synthesis of pyrrolo[1,2-a]quinolines. B) Synthesis of ullazines.
Figure 7: A) Reductive phosphorylation of aryl halides via conPET. B) Selected examples from the substrate sc...
Figure 8: A) Reductive dehalogenation of aryl halides via conPET and selected examples from the substrate sco...
Figure 9: A) Reductive C–H arylation of aryl halides via conPET (top) and selected examples from the substrat...
Figure 10: A) Reductive hydrodehalogenation of aryl halides with Mes-Acr-BF4. B) Selected examples from the su...
Figure 11: A) Reductive hydrodechlorination of aryl chlorides with 4-DPAIPN. B) Proposed formation of CO2•−. C...
Figure 12: A) Reductive conPET borylation with 3CzEPAIPN (top) and selected examples from the substrate scope ...
Figure 13: Scale-up of conPET phosphorylation with 3CzEPAIPN.
Figure 14: A) Borylation of 1d. B) Characteristics and structure of PC1 with green and red parts showing the l...
Figure 15: A) Reductive C–H arylation scope with polysulfide conPET (top) and selected examples from the subst...
Figure 16: Scale-up of A) C–H arylation and B) dehaloborylation with polysulfide photocatalysis in continuous-...
Figure 17: A) Formation of [Ir1]0 and [Ir2]0 upon PET between [Ir1]+ and Et3N. B) Mechanism of multi-photon ta...
Figure 18: A) Reductive hydrodehalogenation of aryl halides via multi-photon tandem photocatalysis. B) Selecte...
Figure 19: A) Carbonylative amidation of aryl halides in continuous flow. B) Selected examples from the substr...
Figure 20: A) General scheme for reductive (RQ) and oxidative quenching (OQ) protocols using [FeIII(btz)3](PF6)...
Figure 21: A) Carbonylative amidation of alkyl iodides with [IrIII(ppy)2(dtbbpy)]PF6. B) Selected examples fro...
Figure 22: A) Carboxylative C–N bond cleavage in cyclic amines. B) Selected examples from the substrate scope....
Figure 23: A) Formal reduction of alkenes to alkanes via transfer hydrogenation. B) Selected examples from the...
Figure 24: A) Birch-type reduction of benzenes with PMP-BPI. B) Selected examples from the substrate scope (sc...
Figure 25: Proposed mechanism of the OH− mediated conPET Birch-type reduction of benzene via generation of sol...
Figure 26: Reductive detosylation of N-tosylated amides with Mes-Acr-BF4. B) Selected examples from the substr...
Figure 27: A) Reductive detosylation of N-tosyl amides by dual PRC. B) Selected examples from the substrate sc...
Figure 28: A) Mechanism of the dual PRC based on PET between [Cu(dap)2]+ and DCA. B) Mechanism of the dual PRC...
Figure 29: A) N–O bond cleavage in Weinreb amides with anthracene. B) N–O bond cleavage in Weinreb amides rely...
Figure 30: A) Pentafluorosulfanylation and fluoride elimination. B) Mechanism of the pentafluorosulfanylation ...
Figure 31: A) α-Alkoxypentafluorosulfanylation (top) and selected examples from the substrate scope (bottom). ...
Figure 32: A) Oxidative amination of arenes with azoles catalyzed by N-Ph PTZ. B) Selected examples from the s...
Figure 33: A) C(sp3)–H bond activation by HAT via chloride oxidation by *N-Ph PTZ•+. B) Proposed mechanism for...
Figure 34: A) Recycling e-PRC C–H azolation of electron-rich arenes with pyrazoles using Mes-Acr+ as a photoca...
Figure 35: A) Radical ion e-PRC direct oxidation of unactivated arenes using TAC+ as an electro-activated phot...
Figure 36: A) Radical ion e-PRC direct oxidation of unactivated arenes using TPA as an electro-activated photo...
Figure 37: Proposed mechanism (top) and mode of preassembly (bottom).
Figure 38: A) Possible preassemblies of reactive (left) vs unreactive (right) arenes. B) Calculated spin densi...
Figure 39: A) Recycling e-PRC C(sp2 )–H acetoxylation of arenes using DDQ as a photocatalyst. B) Proposed cata...
Figure 40: Gram scale hydroxylation of benzene in a recirculated flow setup.
Figure 41: A) Radical ion e-PRC vicinal diamination of alkylarenes using TAC+ as an electro-activated photocat...
Figure 42: A) Sequential oxygenation of multiple adjacent C–H bonds under radical ion e-PRC using TAC+ as an e...
Figure 43: A) Enantioselective recycling e-PRC cyanation of benzylic C–H bonds using ADQS as photocatalyst. B)...
Figure 44: Proposed tandem mechanism by Xu and co-workers.
Figure 45: A) Enantioselective recycling e-PRC decarboxylative cyanation using Cu(acac)2, Ce(OTf)3 and a box l...
Figure 46: A) Enantioselective recycling e-PRC benzylic cyanation using Cu(MeCN)4BF4, box ligand and anthraqui...
Figure 47: A) Radical ion e-PRC acetoxyhydroxylation of aryl olefins using TAC+ as an electro-activated photoc...
Figure 48: Selected examples from the substrate scope.
Figure 49: Photoelectrochemical acetoxyhydroxylation in a recirculated flow setup.
Figure 50: A) Radical ion e-PRC aminooxygenation of aryl olefins using TAC+ as an electro-activated photocatal...
Figure 51: A) Recycling e-PRC C–H alkylation of heteroarenes with organic trifluoroborates using Mes-Acr+ as p...
Figure 52: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using CeCl3·7H2O as catalyst. B) ...
Figure 53: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using Fe(NH4)2(SO4)2·6H2O as cata...
Figure 54: A) Recycling e-PRC C–H alkylation of heteroarenes with alkyl oxalates and 4CzIPN as photocatalyst. ...
Figure 55: A) Recycling e-PRC decarboxylative C–H carbamoylation of heteroarenes using 4CzIPN as photocatalyst...
Figure 56: A) Photoelectrochemical HAT-mediated hydrocarbon activation via the chlorine radical. B) Proposed m...
Figure 57: A) Selected examples from the substrate scope. B) Gram and decagram scale semi-continuous flow PEC ...
Figure 58: A) Photoelectrochemical HAT-mediated dehydrogenative coupling of benzothiazoles with aliphatic C–H ...
Figure 59: A) Photoelectrochemical HAT activation of ethers using electro-activated TAC+ as photocatalyst. B) ...
Figure 60: Selected examples from the substrate scope.
Figure 61: A) Photoelectrochemical HAT-mediated synthesis of alkylated benzimidazo-fused isoquinolinones using...
Figure 62: A) Decoupled photoelectrochemical cerium-catalyzed oxydichlorination of alkynes using CeCl3 as cata...
Figure 63: Proposed decoupled photoelectrochemical mechanism.
Figure 64: A) Decoupled photoelectrochemical ring-opening bromination of tertiary cycloalkanols using MgBr2 as...
Figure 65: A) Recycling e-PRC ring-opening functionalization of cycloalkanols using CeCl3 as catalyst. B) Prop...
Figure 66: Selected examples from the substrate scope of the PEC ring-opening functionalization.
Figure 67: A) Radical ion e-PRC reduction of chloro- and bromoarenes using DCA as catalyst and various accepto...
Figure 68: A) Screening of different phthalimide derivatives as catalyst for the e-PRC reduction of aryl halid...
Figure 69: Screening of different organic catalysts for the e-PRC reduction of trialkylanilium salts.
Figure 70: A) e-PRC reduction of phosphonated phenols and anilinium salts. B) Selected examples from the subst...
Figure 71: A) ConPET and e-PRC reduction of 4-bromobenzonitrile using a naphthalene diimide (NDI) precatalyst ...
Figure 72: A) Radical ion e-PRC reduction of phosphinated aliphatic alcohols with n-BuO-NpMI as catalyst. B) C...
Figure 73: Selected examples from the substrate scope.
Figure 74: A) Recycling e-PRC reductive dimerization of benzylic chlorides using a [Cu2] catalyst. B) Proposed...
Figure 75: A) Decoupled photoelectrochemical C–H alkylation of heteroarenes through deamination of Katritzky s...
Figure 76: Proposed mechanism by Chen and co-workers.
Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine
- Saika Izumi,
- Prasannamani Govindharaj,
- Anna Drewniak,
- Paola Zimmermann Crocomo,
- Satoshi Minakata,
- Leonardo Evaristo de Sousa,
- Piotr de Silva,
- Przemyslaw Data and
- Youhei Takeda
Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48
- ) compound based on a donor–acceptor (D–A) architecture (D = phenoxazine; A = dibenzo[a,j]phenazine) has been developed, and its photophysical properties were characterized. The D–A compound is applicable as an emitting material for efficient organic light-emitting diodes (OLEDs), and its external quantum
- the designed D–A molecule 1, an asymmetric dibenzophenazine electrophile was required. Recently, we have established a synthetic method for such a compound, i.e., 3-trifluoromethanesulfonyldibenzo[a,j]phenazine (DBPHZ-OTf in Scheme 1) to prepare linear-type A–D–A–D compounds [18]. Starting from the
Graphical Abstract
Figure 1: Chemical structures of 1 and POZ-DBPHZ.
Scheme 1: Synthesis of compound 1.
Figure 2: Steady-state UV–vis absorption (Abs) and photoluminescence (PL) spectra of dilute solutions (c ≈ 10...
Figure 3: Time-resolved PL decay profiles (intensity vs delay time) and spectra of 1 in a), b) Zeonex® and c,...
Figure 4: The characteristics of the OLED devices: a) electroluminescence spectra; b) current density-bias ch...
Figure 5: Schematics of the TADF mechanisms along with NTOs for the relevant electronic states for a) D–A com...
Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B
- Emmanuel T. Oluwabusola,
- Olusoji O. Adebisi,
- Fernando Reyes,
- Kojo S. Acquah,
- Mercedes De La Cruz,
- Larry L. Mweetwa,
- Joy E. Rajakulendran,
- Digby F. Warner,
- Deng Hai,
- Rainer Ebel and
- Marcel Jaspars
Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156
- used for the treatment of leprosy and inflammation was inspired by the natural product phenazine [17][18]. Also, pseudomononic acid (mupirocin) isolated from Pseudomonas fluorescens by Fuller and co-workers in 1971 was discovered to possess novel antibacterial activities against 310 clinical isolates
Graphical Abstract
Figure 1: Structures of the new phenolic siderophores 1–5, pseudomonine (6), and salicylic acid (7).
Figure 2: Key HMBC and 1H-1H COSY correlations.
Figure 3: Plausible biosynthetic hypotheses of compounds 1–5.
Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects
- Shivani Gulati,
- Stephy Elza John and
- Nagula Shankaraiah
Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71
- (51) in presence of acetic acid under microwave irradiation for the synthesis of highly functionalized benzopyrans 52. The method was successfully employed for the construction of chromene and phenazine motifs exhibiting the applicability of the protocol to engender diverse chemical entities (Scheme
Graphical Abstract
Figure 1: Marketed drugs with acridine moiety.
Scheme 1: Synthesis of 4-arylacridinediones.
Scheme 2: Proposed mechanism for acridinedione synthesis.
Scheme 3: Synthesis of tetrahydrodibenzoacridinones.
Scheme 4: Synthesis of naphthoacridines.
Scheme 5: Plausible mechanism for naphthoacridines.
Figure 2: Benzoazepines based potent molecules.
Scheme 6: Synthesis of azepinone.
Scheme 7: Proposed mechanism for azepinone formation.
Scheme 8: Synthesis of benzoazulenen-1-one derivatives.
Scheme 9: Proposed mechanism for benzoazulene-1-one synthesis.
Figure 3: Indole-containing pharmacologically active molecules.
Scheme 10: Synthesis of functionalized indoles.
Scheme 11: Plausible mechanism for the synthesis of functionalized indoles.
Scheme 12: Synthesis of spirooxindoles.
Scheme 13: Synthesis of substituted spirooxindoles.
Scheme 14: Plausible mechanism for the synthesis of substituted spirooxindoles.
Scheme 15: Synthesis of pyrrolidinyl spirooxindoles.
Scheme 16: Proposed mechanism for pyrrolidinyl spirooxindoles.
Figure 4: Pyran-containing biologically active molecules.
Scheme 17: Synthesis of functionalized benzopyrans.
Scheme 18: Plausible mechanism for synthesis of benzopyran.
Scheme 19: Synthesis of indoline-spiro-fused pyran derivatives.
Scheme 20: Proposed mechanism for indoline-spiro-fused pyran.
Scheme 21: Synthesis of substituted naphthopyrans.
Figure 5: Marketed drugs with pyrrole ring.
Scheme 22: Synthesis of tetra-substituted pyrroles.
Scheme 23: Mechanism for silica-supported PPA-SiO2-catalyzed pyrrole synthesis.
Scheme 24: Synthesis of pyrrolo[1,10]-phenanthrolines.
Scheme 25: Proposed mechanism for pyrrolo[1,10]-phenanthrolines.
Figure 6: Marketed drugs and molecules containing pyrimidine and pyrimidinones skeletons.
Scheme 26: MWA-MCR pyrimidinone synthesis.
Scheme 27: Two proposed mechanisms for pyrimidinone synthesis.
Scheme 28: MWA multicomponent synthesis of dihydropyrimidinones.
Scheme 29: Proposed mechanism for dihydropyrimidinones.
Figure 7: Biologically active fused pyrimidines.
Scheme 30: MWA- MCR for the synthesis of pyrrolo[2,3-d]pyrimidines.
Scheme 31: Proposed mechanism for pyrrolo[2,3-d]pyrimidines.
Scheme 32: Synthesis of substituted pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 33: Probable pathway for pyrrolo[2,3-d]pyrimidine-2,4-diones.
Scheme 34: Synthesis of pyridopyrimidines.
Scheme 35: Plausible mechanism for the synthesis of pyridopyrimidines.
Scheme 36: Synthesis of dihydropyridopyrimidine and dihydropyrazolopyridine.
Scheme 37: Proposed mechanism for the formation of dihydropyridopyrimidine.
Scheme 38: Synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 39: Plausible mechanism for the synthesis of thiopyrano[4,3-d]pyrimidines.
Scheme 40: Synthesis of decorated imidazopyrimidines.
Scheme 41: Proposed mechanism for imidazopyrimidine synthesis.
Figure 8: Pharmacologically active molecules containing purine bases.
Scheme 42: Synthesis of aza-adenines.
Scheme 43: Synthesis of 5-aza-7-deazapurines.
Scheme 44: Proposed mechanism for deazapurines synthesis.
Figure 9: Biologically active molecules containing pyridine moiety.
Scheme 45: Synthesis of steroidal pyridines.
Scheme 46: Proposed mechanism for steroidal pyridine.
Scheme 47: Synthesis of N-alkylated 2-pyridones.
Scheme 48: Two possible mechanisms for pyridone synthesis.
Scheme 49: Synthesis of pyridone derivatives.
Scheme 50: Postulated mechanism for synthesis of pyridone.
Figure 10: Biologically active fused pyridines.
Scheme 51: Benzimidazole-imidazo[1,2-a]pyridines synthesis.
Scheme 52: Mechanism for the synthesis of benzimidazole-imidazo[1,2-a]pyridines.
Scheme 53: Synthesis of pyrazolo[3,4-b]pyridine-5-spirocycloalkanedione derivatives.
Scheme 54: Proposed mechanism for spiro-pyridines.
Scheme 55: Functionalized macrocyclane-fused pyrazolo[3,4-b]pyridine derivatives.
Scheme 56: Mechanism postulated for macrocyclane-fused pyrazolo[3,4-b]pyridine.
Scheme 57: Generation of pyrazolo[3,4-b]pyridines.
Scheme 58: Proposed mechanism for the synthesis of pyrazolo[3,4-b]pyridines.
Scheme 59: Proposed mechanism for the synthesis of azepinoindole.
Figure 11: Pharmaceutically important molecules with quinoline moiety.
Scheme 60: Povarov-mediated quinoline synthesis.
Scheme 61: Proposed mechanism for Povarov reaction.
Scheme 62: Synthesis of pyrazoloquinoline.
Scheme 63: Plausible mechanism for pyrazoloquinoline synthesis.
Figure 12: Quinazolinones as pharmacologically significant scaffolds.
Scheme 64: Four-component reaction for dihydroquinazolinone.
Scheme 65: Proposed mechanism for dihydroquinazolinones.
Scheme 66: Synthesis purine quinazolinone and PI3K-δ inhibitor.
Scheme 67: Synthesis of fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 68: Proposed mechanism for fused benzothiazolo/benzoimidazoloquinazolinones.
Scheme 69: On-water reaction for synthesis of thiazoloquinazolinone.
Scheme 70: Proposed mechanism for the thiazoloquinazolinone synthesis.
Scheme 71: β-Cyclodextrin-mediated synthesis of indoloquinazolinediones.
Scheme 72: Proposed mechanism for synthesis of indoloquinazolinediones.
Figure 13: Triazoles-containing marketted drugs and pharmacologically active molecules.
Scheme 73: Cu(I) DAPTA-catalyzed 1,2,3-triazole formation.
Scheme 74: Mechanism for Cu(I) DAPTA-catalyzed triazole formation.
Scheme 75: Synthesis of β-hydroxy-1,2,3-triazole.
Scheme 76: Proposed mechanism for synthesis of β-hydroxy-1,2,3-triazoles.
Scheme 77: Synthesis of bis-1,2,4-triazoles.
Scheme 78: Proposed mechanism for bis-1,2,4-triazoles synthesis.
Figure 14: Thiazole containing drugs.
Scheme 79: Synthesis of a substituted thiazole ring.
Scheme 80: Synthesis of pyrazolothiazoles.
Figure 15: Chromene containing drugs.
Scheme 81: Magnetic nanocatalyst-mediated aminochromene synthesis.
Scheme 82: Proposed mechanism for the synthesis of chromenes.
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
- previously unknown heterocyclic systems 1H-carbazolo[3,4-a]phenazine, 7H-quinoxalino[5,6-c]carbazole and 7H-quinolino[8,7-c]carbazole, respectively (SciFinder data). The fourth step of the synthesis of the target helicenes, namely the Sonogashira coupling of iodides 7a and 7c with p-tolylacetylene, was
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...
1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss
- Arnault Heynderickx,
- Sébastien Nénon,
- Olivier Siri,
- Vladimir Lokshin and
- Vladimir Khodorkovsky
Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203
- derivative of quinoxalino[2,3-b]phenazine), which has been fully established in 1987 by the 1H NMR spectrum splitting patterns [11], the compound assumed to be the 5,12-dihydro isomer since 1890 [12]. 1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene (THTAA, 3) bearing the electron-donating NH and accepting =N
- the formation of hydrogen bonds, an approach known as ‘crystal engineering’ (see, for instance, [13][14] and references therein). Indeed, whereas several two-component molecular systems cocrystallizing in a special layered way involving pyrazine, quinoline and phenazine as the H-bond acceptor and
Graphical Abstract
Figure 1: Quinoxaline derivatives 1–3.
Scheme 1: Synthesis of THTTA (3).
Scheme 2: Protonation, alkylation and acylation of 3.
Figure 2: The ORTEP view of 3. Torsion angles within the benzene ring are given in red.
Figure 3: The ORTEP view of 6a. Torsion angles within the benzene ring are given in red.
Figure 4: The ORTEP view of 7a (the iodine counter anion has been omitted for clarity). Torsion angles within...
Scheme 3: Charge transfer and delocalization within 3 and its diprotonated (6a) and monomethylated (7a) deriv...
Figure 5: Normalized absorption spectra of 3 in: toluene (black), acetone (blue), ethanol (green), water (red...
Figure 6: Protonation of 3 in ethanol. Two isosbestic points (IBP) are indicated by arrows.
Figure 7: Absorption spectra of 7a (blue) and 8 (red) in ethanol.
Figure 8: Absorption spectra of 10a (black), 10b (red). Solid curves: in toluene, dashed curves: in acetone.
Figure 9: View of the supramolecular array generated by 3 in the solid state. Color coding: nitrogen, blue; c...
Figure 10: View of the supramolecular array generated by 6a in the solid state. Color coding: nitrogen, blue; ...
Figure 11: View of the supramolecular array generated by 7a in the solid state. Color coding: nitrogen, blue; ...
Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers
- Christian Schütz and
- Martin Empting
Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241
- response. In terms of pathogenicity traits, they are involved in the regulation of genes encoding for enzymes responsible for phenazine biosynthesis (pyocyanin production), hydrogen cyanide synthesis, Lectins LecA and LecB and additional genes involved in biofilm formation, enzymes for rhamnolipid
Graphical Abstract
Figure 1: The four quorum sensing systems in P. aeruginosa las, iqs, rhl, and pqs. Abbreviations: OdDHL, N-(3...
Figure 2: Schematic overview of the PQS biosynthesis and involvement of related metabolites and PqsE in virul...
Figure 3: Anthranilic acid (1) and derivatives thereof (2–4).
Figure 4: Crystal structure of 6-FABA-AMP in complex with PqsA.
Figure 5: Structures of substrate mimetic PqsA inhibitors.
Figure 6: Structures and characteristics of prominent classes of PqsD inhibitors.
Figure 7: Comparison of docking poses of three prototypic PqsD inhibitors: benzamidobenzoic acid derivative 12...
Figure 8: Structures and characteristics of hits against PqsD identified through different methods.
Figure 9: HHQ and PQS analogues as PqsD inhibitors and chemical probe used for screening.
Figure 10: Structure of PqsD-targeting biofilm inhibitor derived from linezolid.
Figure 11: Fragment-based PqsE-inhibitors 24–26.
Figure 12: PqsE co-crystal structures. (A) native product 2-ABA; (B–D) hit fragments 24–26.
Figure 13: Structurally diverse PqsBC-inhibitors 27–30.
Figure 14: Native PqsR ligand HHQ (31) which is converted into PQS (32) by PqsH and synthetic inhibitors 33 an...
Figure 15: Quinazolinone inhibitor 36 (QZN).
Figure 16: Crystal structure of QZN (36) in complex with PqsRCBD.
Figure 17: Structures of best fitting compounds 37–40 obtained from docking studies.
Figure 18: Initial hit 21 and optimized compound 42 (M64).
Figure 19: Co-crystal structure of M64 (42) with PqsRLBD.
Figure 20: M64 (42) as the starting point for further optimization leading to 43, which was further modified a...
Figure 21: Hit fragments from the benzamide (47–48) and oxadiazole class (49–51).
Figure 22: Structures of dual inhibitors 52–55.
Figure 23: Sulfonyl pyrimidines 56–58 acting as dual PqsD/PqsR inhibitors.
Synthesis and photophysical studies of a multivalent photoreactive RuII-calix[4]arene complex bearing RGD-containing cyclopentapeptides
- Sofia Kajouj,
- Lionel Marcelis,
- Alice Mattiuzzi,
- Adrien Grassin,
- Damien Dufour,
- Pierre Van Antwerpen,
- Didier Boturyn,
- Eric Defrancq,
- Mathieu Surin,
- Julien De Winter,
- Pascal Gerbaux,
- Ivan Jabin and
- Cécile Moucheron
Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150
- particular (i) for their ability to sense their environment and (ii) for their photoreactivity towards relevant biological targets [1][2][3][4]. Sensors for biological species are mostly based on complexes bearing the well-known dppz ligand (dppz = dipyrido[3,2-a:2’,3’-c]phenazine) and its derivatives. J. K
Graphical Abstract
Figure 1: Targeted multivalent phototherapeutic agent and its calix[4]arene-based precursor. RGD = Arg–Gly–As...
Scheme 1: Synthesis of RuII-calix[4]arene complex 7.
Scheme 2: Synthesis of RuII-calix[4]arene-[c-(RGDfK)]4 conjugate 9.
Figure 2: MD snapshot showing an optimized model of conjugate 9. RGDfK units are depicted in orange ribbons, ...
Figure 3: Absorption and emission spectra of RuII-calix[4]arene-[c-(RGDfK)]4 conjugate 9 in water.
Figure 4: Luminescence intensity and excited state lifetime of conjugate 9 in the presence of GMP measured in...
Figure 5: Transient absorption spectra of RuII-calix[4]arene-[c-(RGDfK)]4 conjugate 9 (in 10 mM Tris·HCl buff...
Figure 6: MALDI–MS analysis of a solution containing conjugate 9 and GMP after continuous light irradiation. ...
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
Mechanochemical synthesis of small organic molecules
- Tapas Kumar Achar,
- Anima Bose and
- Prasenjit Mal
Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186
- % p-toluenesulfonic acid as catalyst. Using this process they could isolate 72–96% of pyrazaacene, phenazine, bis(phenazine), bis(quinoxaine) derivatives (Scheme 41). Major advantages of this mechanomilling methods were time efficient (2–4 h), simple purification procedure (washing with polar solvent
Graphical Abstract
Scheme 1: Mechanochemical aldol condensation reactions [48].
Scheme 2: Enantioselective organocatalyzed aldol reactions under mechanomilling. a) Based on binam-(S)-prolin...
Scheme 3: Mechanochemical Michael reaction [51].
Scheme 4: Mechanochemical organocatalytic asymmetric Michael reaction [52].
Scheme 5: Mechanochemical Morita–Baylis–Hillman (MBH) reaction [53].
Scheme 6: Mechanochemical Wittig reactions [55].
Scheme 7: Mechanochemical Suzuki reaction [56].
Scheme 8: Mechanochemical Suzuki–Miyaura coupling by LAG [57].
Scheme 9: Mechanochemical Heck reaction [59].
Scheme 10: a) Sonogashira coupling under milling conditions. b) The representative example of a double Sonogas...
Scheme 11: Copper-catalyzed CDC reaction under mechanomilling [67].
Scheme 12: Asymmetric alkynylation of prochiral sp3 C–H bonds via CDC [68].
Scheme 13: Fe(III)-catalyzed CDC coupling of 3-benzylindoles [69].
Scheme 14: Mechanochemical synthesis of 3-vinylindoles and β,β-diindolylpropionates [70].
Scheme 15: Mechanochemical C–N bond construction using anilines and arylboronic acids [78].
Scheme 16: Mechanochemical amidation reaction from aromatic aldehydes and N-chloramine [79].
Scheme 17: Mechanochemical CDC between benzaldehydes and benzyl amines [81].
Scheme 18: Mechanochemical protection of -NH2 and -COOH group of amino acids [85].
Scheme 19: Mechanochemical Ritter reaction [87].
Scheme 20: Mechanochemical synthesis of dialkyl carbonates [90].
Scheme 21: Mechanochemical transesterification reaction using basic Al2O3 [91].
Scheme 22: Mechanochemical carbamate synthesis [92].
Scheme 23: Mechanochemical bromination reaction using NaBr and oxone [96].
Scheme 24: Mechanochemical aryl halogenation reactions using NaX and oxone [97].
Scheme 25: Mechanochemical halogenation reaction of electron-rich arenes [88,98].
Scheme 26: Mechanochemical aryl halogenation reaction using trihaloisocyanuric acids [100].
Scheme 27: Mechanochemical fluorination reaction by LAG method [102].
Scheme 28: Mechanochemical Ugi reaction [116].
Scheme 29: Mechanochemical Passerine reaction [116].
Scheme 30: Mechanochemical synthesis of α-aminonitriles [120].
Scheme 31: Mechanochemical Hantzsch pyrrole synthesis [121].
Scheme 32: Mechanochemical Biginelli reaction by subcomponent synthesis approach [133].
Scheme 33: Mechanochemical asymmetric multicomponent reaction[134].
Scheme 34: Mechanochemical Paal–Knorr pyrrole synthesis [142].
Scheme 35: Mechanochemical synthesis of benzothiazole using ZnO nano particles [146].
Scheme 36: Mechanochemical synthesis of 1,2-di-substituted benzimidazoles [149].
Scheme 37: Mechanochemical click reaction using an alumina-supported Cu-catalyst [152].
Scheme 38: Mechanochemical click reaction using copper vial [155].
Scheme 39: Mechanochemical indole synthesis [157].
Scheme 40: Mechanochemical synthesis of chromene [158].
Scheme 41: Mechanochemical synthesis of azacenes [169].
Scheme 42: Mechanochemical oxidative C-P bond formation [170].
Scheme 43: Mechanochemical C–chalcogen bond formation [171].
Scheme 44: Solvent-free synthesis of an organometallic complex.
Scheme 45: Selective examples of mechano-synthesis of organometallic complexes. a) Halogenation reaction of Re...
Scheme 46: Mechanochemical activation of C–H bond of unsymmetrical azobenzene [178].
Scheme 47: Mechanochemical synthesis of organometallic pincer complex [179].
Scheme 48: Mechanochemical synthesis of tris(allyl)aluminum complex [180].
Scheme 49: Mechanochemical Ru-catalyzed olefin metathesis reaction [181].
Scheme 50: Rhodium(III)-catalyzed C–H bond functionalization under mechanochemical conditions [182].
Scheme 51: Mechanochemical Csp2–H bond amidation using Ir(III) catalyst [183].
Scheme 52: Mechanochemical Rh-catalyzed Csp2–X bond formation [184].
Scheme 53: Mechanochemical Pd-catalyzed C–H activation [185].
Scheme 54: Mechanochemical Csp2–H bond amidation using Rh catalyst.
Scheme 55: Mechanochemical synthesis of indoles using Rh catalyst [187].
Scheme 56: Mizoroki–Heck reaction of aminoacrylates with aryl halide in a ball-mill [58].
Scheme 57: IBX under mechanomilling conditions [8].
Scheme 58: Thiocarbamoylation of anilines; trapping of reactive aryl-N-thiocarbamoylbenzotriazole intermediate...
Spin state switching in iron coordination compounds
- Philipp Gütlich,
- Ana B. Gaspar and
- Yann Garcia
Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39
Graphical Abstract
Figure 1: Change of electron distribution between HS and LS states of an octahedral iron(II) coordination com...
Figure 2: Types of spin transition curves in terms of the molar fraction of HS molecules, γHS(T), as a functi...
Figure 3: Single crystal UV–vis spectra of the spin crossover compound [Fe(ptz)6](BF4)2 (ptz = 1-propyltetraz...
Figure 4: Thermal spin crossover in [Fe(ptz)6](BF4)2 (ptz = 1-propyltetrazole) recorded at three different te...
Figure 5: (a) Mössbauer spectra of the LS compound [Fe(phen)3]X2 recorded over the temperature range 300–5 K....
Figure 6: (left) Demonstration of light-induced spin state trapping (LIESST) in [Fe(ptz)6]BF4)2 with 57Fe Mös...
Figure 7: Schematic representation of the pressure influence (p2 > p1) on the LS and HS potential wells of an...
Figure 8: χMT versus T curves at different pressures for [Fe(phen)2(NCS)2], polymorph II. (Reproduced with pe...
Figure 9: Molecular structure (a) and γHS(T) curves at different pressures for [CrI2(depe)2] (b) (Reproduced ...
Figure 10: HS molar fraction γHS versusT at different pressures for [Fe(phy)2](BF4)2. The hysteresis loop broa...
Figure 11: Proposed structure of the polymeric [Fe(4R-1,2,4-triazole)3]2+ spin crossover cation (a) and plot o...
Figure 12: Temperature dependence of the HS fraction γHS(T), determined from Mössbauer spectra of [Fe(II)xZn1-x...
Figure 13: Influence of the noncoordinated anion on the spin transition curve γHS(T) near the transition tempe...
Figure 14: Spin transition curves γHS(T) for different solvates of the SCO complexes. [Fe(II)(2-pic)3]Cl2·Solv...
Figure 15: ST curves γHS(T) of the deuterated solvates of [Fe(II)(2-pic)3]Cl2·Solv with Solv = C2D5OH and C2H5...
Figure 16: Sketch of the two-step spin transition; [LS–LS] pair is diamagnetic, [LS–HS] is paramagnetic and th...
Figure 17: (left) Temperature dependence of χMT for {[Fe(L)(NCX)2]2bpym}(L = bpym or bt and X = S or Se). (rig...
Figure 18: Temperature dependence of χMT for [bpym, NCS−] (left) and [bpym, NCSe−] (right) at different pressu...
Figure 19: 57Fe Mössbauer spectra of [bpym, NCSe−] measured at 4.2 K at zero field (a) and at 5 T (b) (see tex...
Figure 20: Temperature dependence of χMT for [Fe2(L)3](ClO4)4·2H2O showing a complete two-step spin conversion...
Figure 21: (a) View of the dinuclear unit in the crystal structure of [Fe2(Hsaltrz)5(NCS)4]·4MeOH. (b) Tempera...
Figure 22: (left) AFM pattern recorded in tapping mode at room temperature on hexagonal single crystals of [Fe3...
Figure 23: (right) Stepwise SCO in an Fe4 [2 × 2] grid, which reveals a smooth magnetic profile under ambient ...
Figure 24: (left) View of the discrete nanoball made of Fe(II) SCO units as well as Cu(I) building blocks. (ri...
Figure 25:
(left) Linear dependency between T1/2 in the heating (Δ) and cooling (![[Graphic 1]](/bjoc/content/inline/1860-5397-9-39-i3.png?max-width=637&scale=1.18182)
) modes versus the anion volu...
Figure 26: (left) View of the linear chain structure of [Fe(1,2-bis(tetrazol-1-yl)propane)3]2+ along the a axi...
Figure 27: (left) View of the 2D layered structure of [Fe(btr)2(NCS)2]·H2O (at 293 K). The water molecules (in...
Figure 28: (left) Three interpenetrated square networks for [Fe(bpb)2(NCS)2]·MeOH. (right) χMT versus T plot s...
Figure 29: Part of the crystal structure of [Fe{N(entz)3}](BF4)2 (T = 293 K) [335,336]. (Reproduced with permission fro...
Figure 30: (left) Projection of the crystal structure of [Fe(btr)3](ClO4)2 along the c axis revealing a 3D str...
Figure 31: Size-dependent SCO properties in [Fe(pz)Pt(CN)4] (left), change of color upon spin state transition...
Figure 32: Schematic showing the epitaxial growth of polymer {Fe(pz)[Pt(CN)4]} and the spin transition propert...
Figure 33: Microcontact printing (μCP) of nanodots on Si-wafer of [Fe(ptz)6](BF4)2 after deposition of crystal...
Figure 34: (left) Projection of the two independent cations of [Fe(C6–trenH)]2+ with atom numbering scheme (15...
Figure 35: (a) χMT versus T for [Fe(C16-trenH)]Cl2·0.5H2O and variation of the distance d with temperature (T)...
Figure 36: Schematic illustration of the structure of compounds [Fe(Cn-tba)3]X2 adopting a columnar mesophase ...
Figure 37: Temperature dependence of the magnetic moment (M) at 1000 Oe and DSC profiles (inset; 5 °C/min) of ...
Figure 38: Porous structure of the SCO-PMOFs {Fe(pz)[M(II)(CN)4]} (left), representation of the host–guest int...
Figure 39: Porous structure of the guest-free SCO-PMOF’s {Fe(pz)[M(II)(CN)4]} (left), magnetic properties of t...
Figure 40: (left) The 3D porous structure of {Fe(pz)[Pt(CN)4]}·0.5(CS(NH2)2) (1) and {Fe(pz)[Pd(CN)4]}·1.5H2O·...
Figure 41: Top: The 3D porous structure of {Fe(dpe)[Pt(CN)4]}·phenazine in a direction close to [101] emphasiz...
Figure 42: View of the segregated stacking of [Ni(dmit)2]− and [Fe(sal2-trien)]+ in [Fe(qsal)2][Ni(dmit)2]3·CH3...
Figure 43: Thin films based on Fe(III) compounds coordinated to Terthienyl-substituted QsalH ligands [434] together...
Figure 44: Left: Temperature-dependent emission spectra for [Fe2(Hsaltrz)5(NCS)4]·4MeOH at λex = 350 nm over t...
Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663
- Orwah Saleh,
- Katrin Flinspach,
- Lucia Westrich,
- Andreas Kulik,
- Bertolt Gust,
- Hans-Peter Fiedler and
- Lutz Heide
Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57
- obtained in strain M512. Mutations in the rpoB and rpsL genes of the host, which result in increased production of other secondary metabolites, had no beneficial effect on the production of phenazines. The heterologous expression strains produced, besides the known phenazine compounds, a new prenylated
- phenazine, termed endophenazine E. The structure of endophenazine E was determined by high-resolution mass spectrometry and by one- and two-dimensional NMR spectroscopy. It represented a conjugate of endophenazine A (9-dimethylallylphenazine-1-carboxylic acid) and L-glutamine (L-Gln), with the carboxyl
- group of endophenazine A forming an amide bond to the α-amino group of L-Gln. Gene inactivation experiments in the gene cluster proved that ppzM codes for a phenazine N-methyltransferase. The gene ppzV apparently represents a new type of TetR-family regulator, specifically controlling the prenylation in
Graphical Abstract
Figure 1: The endophenazine biosynthetic gene cluster from Streptomyces anulatus 9663 and the structures of p...
Figure 2: Production of prenylated phenazines after heterologous expression of the endophenazine gene cluster...
Figure 3: HPLC analysis of mycelia of the heterologous expression strain S. coelicolor M512(ppzOS04) after fi...
Figure 4: Extracted ion chromatograms for the mass of endophenazine B (m/z [M + H]+ = 323) in S. coelicolor M...
Syntheses and properties of thienyl-substituted dithienophenazines
- Annemarie Meyer,
- Eva Sigmund,
- Friedhelm Luppertz,
- Gregor Schnakenburg,
- Immanuel Gadaczek,
- Thomas Bredow,
- Stefan-S. Jester and
- Sigurd Höger
Beilstein J. Org. Chem. 2010, 6, 1180–1187, doi:10.3762/bjoc.6.135
- different lengths of the oligomeric thiophene units (quaterthiophenes and sexithiophenes) was synthesized. The thiophene and phenazine units act as electron donors and acceptors, respectively, resulting in characteristic absorption spectra. The optical spectra were calculated using time-dependent density
- coupling products with thiophene boronic acids. In both cases the thiophene units of the molecules act as electron rich parts (donors, D), whereas the phenazine moieties serve as electron deficient parts (acceptors, A), leading to a bathochromic shift of the UV–vis spectra in comparison with the non
- -condensed thiophene analogues. These assignments of the thiophene moieties as donors and the phenazine moieties as acceptors are confirmed by quantum-chemical calculations at the density-functional level. Additionally, one of the compounds forms a self-assembled monolayer on a HOPG surface, as imaged by
Graphical Abstract
Scheme 1: Synthesis of 4. a) 1) EtLi, Et2O, −78 °C, 1 h; 2) (COOMe)2, Et2O, −78 °C, 2 h, 33%; b) FeCl3, MeNO2...
Scheme 2: Synthesis of 8. a) Pd(PPh3)4, Na2CO3, toluene, EtOH, H2O, reflux, 87%; b) oxalyl chloride, 1,2-dich...
Scheme 3: Preparation of phenazine isomers. a) AcOH, 50 °C, 2 h, 93% (10a), 53% (10b). b) AcOH, 50 °C, 2 h, 6...
Scheme 4: Suzuki–Miyaura reactions with 10a/10b. a) Pd(PPh3)4, Na2CO3, toluene, EtOH, H2O, reflux, 23% (12a),...
Scheme 5: Suzuki–Miyaura reactions with 11a/11b. a) Pd(PPh3)4, Na2CO3, toluene, EtOH, H2O, reflux, 50% (16), ...
Figure 1: a) Absorption (solid lines) and emission (dotted lines) spectra of compounds 12a (blue), 13 (red), ...
Figure 2: Calculated absorption spectra of (a) 19, (b) 20, (c) 12a, (d) 13 with R=CH3, (e) 16 and (f) 17a. In...
Figure 3: Self-assembled monolayer of 12b on HOPG. a) STM image (VS = −0.8 V, It = 80 pA, image size 25.0 × 2...
One-pot three-component synthesis of quinoxaline and phenazine ring systems using Fischer carbene complexes
- Priyabrata Roy and
- Binay Krishna Ghorai
Beilstein J. Org. Chem. 2010, 6, No. 52, doi:10.3762/bjoc.6.52
- the synthesis of quinoxaline and phenazine ring systems has been investigated. This involves the generation of furo[3,4-b]pyrazine and furo[3,4-b]quinoxaline as transient intermediates, which were trapped with Diels–Alder dienophiles. This is the first report on furo[3,4-b]pyrazine intermediates
- . Keywords: azaisobenzofuran; Diels–Alder; Fischer carbene complex; phenazine; quinoxaline; Introduction Nitrogen-containing heterocycles are abundant in nature and exhibit diverse and important biological properties [1]. Quinoxaline and phenazine derivatives are important classes of nitrogen containing
- heterocycles which exhibit a wide range of biological activities. Many phenazine compounds are found in nature and are produced by bacteria such as Pseudomonas spp., Streptomyces spp. and Pantoea agglomerans. These phenazine natural products have been implicated in the virulence and competitive fitness of the
Graphical Abstract
Scheme 1: Synthetic plan towards quinoxaline derivatives.
Scheme 2: Preparation of o-alkynyl carbonyl derivatives 1. A: pyrazine series; B,C: quinoxaline series.
Scheme 3: Synthesis of quinoxaline derivative.
Scheme 4: Synthesis of azahydrophenanthrone derivatives.
Molecular recognition of organic ammonium ions in solution using synthetic receptors
- Andreas Späth and
- Burkhard König
Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32
Graphical Abstract
Figure 1: Biologically important amines and quaternary ammonium salts: histamine (1), dopamine (2) and acetyl...
Figure 2: Crown ether 18-crown-6.
Figure 3: Conformations of 18-crown-6 (4) in solvents of different polarity.
Figure 4: Binding topologies of the ammonium ion depending on the crown ring size.
Figure 5: A “pseudorotaxane” structure consisting of 24-crown-8 and a secondary ammonium ion (5); R = Ph.
Figure 6: Typical examples of azacrown ethers, cryptands and related aza macrocycles.
Figure 7: Binding of ammonium to azacrown ethers and cryptands [111-113].
Figure 8: A 19-crown-6-ether with decalino blocking groups (11) and a thiazole-dibenzo-18-crown-6-ether (12).
Figure 9: 1,3-Bis(6-oxopyridazin-1-yl)propane derivatives 13 and 14 by Campayo et al.
Figure 10: Fluorescent azacrown-PET-sensors based on coumarin.
Figure 11: Two different pyridino-cryptands (17 and 18) compared to a pyridino-crown (19); chiral ammonium ion...
Figure 12: Pyridino-18-crown-6 ligand (21), a similar acridino-18-crown-6 ligand (22) and a structurally relat...
Figure 13: Ciral pyridine-azacrown ether receptors 24.
Figure 14: Chiral 15-crown-5 receptors 26 and an analogue 18-crown-6 ligand 27 derived from amino alcohols.
Figure 15: C2-symmetric chiral 18-crown-6 amino alcohol derivatives 28 and related macrocycles.
Figure 16: Macrocycles with diamide-diester groups (30).
Figure 17: C2-symmetric chiral aza-18-crown-6 ethers (31) with phenethylamine residues.
Figure 18: Chiral C-pivot p-methoxy-phenoxy-lariat ethers.
Figure 19: Chiral lariat crown ether 34.
Figure 20: Sucrose-based chiral crown ether receptors 36.
Figure 21: Permethylated fructooligosaccharide 37 showing induced-fit chiral recognition.
Figure 22: Biphenanthryl-18-crown-6 derivative 38.
Figure 23: Chiral lariat crown ethers derived from binol by Fuji et al.
Figure 24: Chiral phenolic crown ether 41 with “aryl chiral barriers” and guest amines.
Figure 25: Chiral bis-crown receptor 43 with a meso-ternaphthalene backbone.
Figure 26: Chromogenic pH-dependent bis-crown chemosensor 44 for diamines.
Figure 27: Triamine guests for binding to receptor 44.
Figure 28: Chiral bis-crown phenolphthalein chemosensors 46.
Figure 29: Crown ether amino acid 47.
Figure 30: Luminescent receptor 48 for bis-alkylammonium guests.
Figure 31: Luminescent CEAA (49a), a bis-CEAA receptor for amino acids (49b) and the structure of lysine bindi...
Figure 32: Luminescent CEAA tripeptide for binding small peptides.
Figure 33: Bis crown ether 51a self assembles co-operatively with C60-ammonium ion 51b.
Figure 34: Triptycene-based macrotricyclic dibenzo-[24]-crown-8 ether host 52 and guests.
Figure 35: Copper imido diacetic acid azacrown receptor 53a and the suggested His-Lys binding motif; a copper ...
Figure 36: Urea (54) and thiourea (55) benzo crown receptor for transport and extraction of amino acids.
Figure 37: Crown pyryliums ion receptors 56 for amino acids.
Figure 38: Ditopic sulfonamide bridged crown ether receptor 57.
Figure 39: Luminescent peptide receptor 58.
Figure 40: Luminescent receptor 59 for the detection of D-glucosamine hydrochloride in water/ethanol and lumin...
Figure 41: Guanidinium azacrown receptor 61 for simple amino acids and ditopic receptor 62 with crown ether an...
Figure 42: Chiral bicyclic guanidinium azacrown receptor 63 and similar receptor 64 for the enantioselective t...
Figure 43: Receptors for zwitterionic species based on luminescent CEAAs.
Figure 44: 1,10-Azacrown ethers with sugar podand arms and the anticancer agent busulfan.
Figure 45: Benzo-18-crown-6 modified β-cyclodextrin 69 and β-cyclodextrin functionalized with diaza-18-crown-6...
Figure 46: Receptors for colorimetric detection of primary and secondary ammonium ions.
Figure 47: Porphyrine-crown-receptors 72.
Figure 48: Porphyrin-crown ether conjugate 73 and fullerene-ammonium ion guest 74.
Figure 49: Calix[4]arene (75a), homooxocalix[4]arene (75b) and resorcin[4]arene (75c) compared (R = H, alkyl c...
Figure 50: Calix[4]arene and ammonium ion guest (R = H, alkyl, OAcyl etc.), possible binding sites; A: co-ordi...
Figure 51: Typical guests for studies with calixarenes and related molecules.
Figure 52: Lower rim modified p-tert-butylcalix[5]arenes 82.
Figure 53: The first example of a water soluble calixarene.
Figure 54: Sulfonated water soluble calix[n]arenes that bind ammonium ions.
Figure 55: Displacement assay for acetylcholine (3) with a sulfonato-calix[6]arene (84b).
Figure 56: Amino acid inclusion in p-sulfonatocalix[4]arene (84a).
Figure 57: Calixarene receptor family 86 with upper and lower rim functionalization.
Figure 58: Calix[6]arenes 87 with one carboxylic acid functionality.
Figure 59: Sulfonated calix[n]arenes with mono-substitution at the lower rim systematically studied on their r...
Figure 60: Cyclotetrachromotropylene host (91) and its binding to lysine (81c).
Figure 61: Calixarenes 92 and 93 with phosphonic acids groups.
Figure 62: Calix[4]arene tetraphosphonic acid (94a) and a double bridged analogue (94b).
Figure 63: Calix[4]arene tetraphosphonic acid ester (92c) for surface recognition experiments.
Figure 64: Calixarene receptors 95 with α-aminophosphonate groups.
Figure 65: A bridged homocalix[3]arene 95 and a distally bridged homocalix[4]crown 96.
Figure 66: Homocalix[3]arene ammonium ion receptor 97a and the Reichardt’s dye (97b) for colorimetric assays.
Figure 67: Chromogenic diazo-bridged calix[4]arene 98.
Figure 68: Calixarene receptor 99 by Huang et al.
Figure 69: Calixarenes 100 reported by Parisi et al.
Figure 70: Guest molecules for inclusion in calixarenes 100: DAP × 2 HCl (101a), APA (101b) and Lys-OMe × 2 HC...
Figure 71: Different N-linked peptido-calixarenes open and with glycol chain bridges.
Figure 72: (S)-1,1′-Bi-2-naphthol calixarene derivative 104 published by Kubo et al.
Figure 73: A chiral ammonium-ion receptor 105 based on the calix[4]arene skeleton.
Figure 74: R-/S-phenylalaninol functionalized calix[6]arenes 106a and 106b.
Figure 75: Capped homocalix[3]arene ammonium ion receptor 107.
Figure 76: Two C3 symmetric capped calix[6]arenes 108 and 109.
Figure 77: Phosphorous-containing rigidified calix[6]arene 110.
Figure 78: Calix[6]azacryptand 111.
Figure 79: Further substituted calix[6]azacryptands 112.
Figure 80: Resorcin[4]arene (75c) and the cavitands (113).
Figure 81: Tetrasulfonatomethylcalix[4]resorcinarene (114).
Figure 82: Resorcin[4]arenes (115a/b) and pyrogallo[4]arenes (115c, 116).
Figure 83: Displacement assay for acetylcholine (3) with tetracyanoresorcin[4]arene (117).
Figure 84: Tetramethoxy resorcinarene mono-crown-5 (118).
Figure 85: Components of a resorcinarene based displacement assay for ammonium ions.
Figure 86: Chiral basket resorcin[4]arenas 121.
Figure 87: Resorcinarenes with deeper cavitand structure (122).
Figure 88: Resorcinarene with partially open deeper cavitand structure (123).
Figure 89: Water-stabilized deep cavitands with partially structure (124, 125).
Figure 90: Charged cavitands 126 for tetralkylammonium ions.
Figure 91: Ditopic calix[4]arene receptor 127 capped with glycol chains.
Figure 92: A calix[5]arene dimer for diammonium salt recognition.
Figure 93: Calixarene parts 92c and 129 for the formation molecular capsules.
Figure 94: Encapsulation of a quaternary ammonium cation by two resorcin[4]arene molecules (NMe4+@[75c]2 × Cl−...
Figure 95: Encapsulation of a quaternary ammonium cation by six resorcin[4]arene molecules (NMe3D+@[130]6 × Cl−...
Figure 96: Structure and schematic of cucurbit[6]uril (CB[6], 131a).
Figure 97: Cyclohexanocucurbit[6]uril (CB′[6], 132) and the guest molecule spermine (133).
Figure 98: α,α,δ,δ-Tetramethylcucurbit[6]uril (134).
Figure 99: Structure of the cucurbituril-phthalhydrazide analogue 135.
Figure 100: Organic cavities for the displacement assay for amine differentiation.
Figure 101: Displacement assay methodology for diammonium- and related guests involving cucurbiturils and some ...
Figure 102: Nor-seco-Cucurbituril (±)-bis-ns-CB[6] (140) and guest molecules.
Figure 103: The cucurbit[6]uril based complexes 141 for chiral discrimination.
Figure 104: Cucurbit[7]uril (131c) and its ferrocene guests (142) opposed.
Figure 105: Cucurbit[7]uril (131c) guest inclusion and representative guests.
Figure 106: Cucurbit[7]uril (131c) binding to succinylcholine (145) and different bis-ammonium and bis-phosphon...
Figure 107: Paraquat-cucurbit[8]uril complex 149.
Figure 108: Gluconuril-based ammonium receptors 150.
Figure 109: Examples of clefts (151a), tweezers (151b, 151c, 151d) and clips (151e).
Figure 110: Kemp’s triacid (152a), on example of Rebek’s receptors (152b) and guests.
Figure 111: Amino acid receptor (154) by Rebek et al.
Figure 112: Hexagonal lattice designed hosts by Bell et al.
Figure 113: Bell’s amidinium receptor (156) and the amidinium ion (157).
Figure 114: Aromatic phosphonic acids.
Figure 115: Xylene phosphonates 159 and 160a/b for recognition of amines and amino alcohols.
Figure 116: Bisphosphonate recognition motif 161 for a colorimetric assay with alizarin complexone (163) for ca...
Figure 117: Bisphosphonate/phosphate clip 164 and bisphosphonate cleft 165.
Figure 118: N-Methylpyrazine 166a, N-methylnicotinamide iodide (166b) and NAD+ (166c).
Figure 119: Bisphosphate cavitands.
Figure 120: Bisphosphonate 167 of Schrader and Finocchiaro.
Figure 121: Tweezer 168 for noradrenaline (80b).
Figure 122: Different tripods and heparin (170).
Figure 123: Squaramide based receptors 172.
Figure 124: Cage like NH4+ receptor 173 of Kim et al.
Figure 125: Ammonium receptors 174 of Chin et al.
Figure 126: 2-Oxazolin-based ammonium receptors 175a–d and 176 by Ahn et al.
Figure 127: Racemic guest molecules 177.
Figure 128: Tripods based on a imidazole containing macrocycle (178) and the guest molecules employed in the st...
Figure 129: Ammonium ion receptor 180.
Figure 130: Tetraoxa[3.3.3.3]paracyclophanes 181 and a cyclophanic tetraester (182).
Figure 131: Peptidic bridged paraquat-cyclophane.
Figure 132: Shape-selective noradrenaline host.
Figure 133: Receptor 185 for binding of noradrenaline on surface layers from Schrader et al.
Figure 134: Tetraphosphonate receptor for binding of noradrenaline.
Figure 135: Tetraphosphonate 187 of Schrader and Finocchiaro.
Figure 136: Zinc-Porphyrin ammonium-ion receptors 188 and 189 of Mizutani et al.
Figure 137: Zinc porphyrin receptor 190.
Figure 138: Zinc porphyrin receptors 191 capable of amino acid binding.
Figure 139: Zinc-porphyrins with amino acid side chains for stereoinduction.
Figure 140: Bis-zinc-bis-porphyrin based on Tröger’s base 193.
Figure 141: BINAP-zinc-prophyrin derivative 194 and it’s guests.
Figure 142: Bisaryl-linked-zinc-porphyrin receptors.
Figure 143: Bis-zinc-porphyrin 199 for diamine recognition and guests.
Figure 144: Bis-zinc-porphyrin crown ether 201.
Figure 145: Bis-zinc-porphyrin 202 for stereodiscrimination (L = large substituent; S = small substituent).
Figure 146: Bis-zinc-porphyrin[3]rotaxane and its copper complex and guests.
Figure 147: Dien-bipyridyl ligand 206 for co-ordination of two metal atoms.
Figure 148: The ligand and corresponding tetradentate co-complex 207 serving as enantioselective receptor for a...
Figure 149: Bis(oxazoline)–copper(II) complex 208 for the recognition of amino acids in aqueous solution.
Figure 150: Zinc-salen-complexes 209 for the recognition tertiary amines.
Figure 151: Bis(oxazoline)–copper(II) 211 for the recognition of amino acids in aqueous solution.
Figure 152: Zn(II)-complex of a C2 terpyridine crown ether.
Figure 153: Displacement assay and receptor for aspartate over glutamate.
Figure 154: Chiral complex 214 for a colorimetric displacement assay for amino acids.
Figure 155: Metal complex receptor 215 with tripeptide side arms.
Figure 156: A sandwich complex 216 and its displaceable dye 217.
Figure 157: Lanthanide complexes 218–220 for amino acid recognition.
Figure 158: Nonactin (221), valinomycin (222) and vancomycin (223).
Figure 159: Monesin (224a) and a chiral analogue for enantiodiscrimination of ammonium guests (224b).
Figure 160: Chiral podands (226) compared to pentaglyme-dimethylether (225) and 18-crown-6 (4).
Figure 161: Lasalocid A (228).
Figure 162: Lasalocid derivatives (230) of Sessler et al.
Figure 163: The Coporphyrin I tetraanion (231).
Figure 164: Linear and cyclic peptides for ammonium ion recognition.
Figure 165: Cyclic and bicyclic depsipeptides for ammonium ion recognition.
Figure 166: α-Cyclodextrin (136a) and novocaine (236).
Figure 167: Helical diol receptor 237 by Reetz and Sostmann.
Figure 168: Ammonium binding spherand by Cram et al. (238a) and the cyclic[6]metaphenylacetylene 238b in compar...
Figure 169: Receptor for peptide backbone and ammonium binding (239).
Figure 170: Anion sensor principle with 3-hydroxy-2-naphthanilide of Jiang et al.
Figure 171: 7-bromo-3-hydroxy-N-(2-hydroxyphenyl)naphthalene 2-carboxamide (241) and its amine binding.
Figure 172: Naturally occurring catechins with affinity to quaternary ammonium ions.
Figure 173: Spiropyran (244) and merocyanine form (244a) of the amino acid receptors of Fuji et al.
Figure 174: Coumarin aldehyde (245) and its iminium species with amino acid bound (245a) by Glass et al.
Figure 175: Coumarin aldehyde appended with boronic acid.
Figure 176: Quinolone aldehyde dimers by Glass et al.
Figure 177: Chromogenic ammonium ion receptors with trifluoroacetophenone recognition motifs.
Figure 178: Chromogenic ammonium ion receptor with trifluoroacetophenone recognition motif bound on different m...
