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Search for "cadmium" in Full Text gives 13 result(s) in Beilstein Journal of Organic Chemistry.
Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles
- Periklis X. Kolagkis,
- Eirini M. Galathri and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36
- research group explored the activity of cadmium sulfide (CdS) nanotubes as heterogeneous nanocatalysts for the electrophilic condensation between aldehydes and indoles [106]. The nanorods were obtained with a solvothermal technique, where thiourea and cadmium nitrate were mixed in ethylenediamine for 10
Graphical Abstract
Scheme 1: Examples of BIMs used for their medicinal properties.
Scheme 2: Mechanisms for the synthesis of BIMs using protic or Lewis acids as catalysts.
Scheme 3: Synthesis of bis(indolyl)methanes using DBDMH.
Scheme 4: Competition experiments and synthesis of bis(indolyl)methanes using DBDMH.
Scheme 5: Proposed mechanism for formation of BIM of using DBDMH.
Scheme 6: Synthesis of bis(indolyl)methanes using I2.
Scheme 7: General reaction mechanism upon halogen bonding.
Scheme 8: Synthesis of bis(indolyl)methanes using I2, introduced by Ji.
Scheme 9: Synthesis of bis(indolyl)methanes using Br2 in CH3CN.
Scheme 10: Βidentate halogen-bond donors.
Scheme 11: Synthesis of bis(indolyl)methanes using bidentate halogen-bond donor 26.
Scheme 12: Proposed reaction mechanism.
Scheme 13: Synthesis of bis(indolyl)methanes using iodoalkyne as catalyst.
Scheme 14: Proposed reaction mechanism.
Scheme 15: Optimized reaction conditions used by Ramshini.
Scheme 16: Activation of the carbonyl group by HPA/TPI-Fe3O4.
Scheme 17: Synthesis of BIMs in the presence of nanoAg-Pt/SiO2-doped silicate.
Scheme 18: Mechanism of action proposed by Khalafi-Nezhad et al.
Scheme 19: Activation of the carbonyl group by the Cu–isatin Schiff base complex.
Scheme 20: Optimum reaction conditions published by Jain.
Scheme 21: Organocatalytic protocol utilizing nanoparticles introduced by Bankar.
Scheme 22: Activation of the carbonyl group by the AlCl3·6H2O-SDS-SiO2 complex.
Scheme 23: Optimal reaction conditions for the aforementioned nano-Fe3O4 based catalysts.
Scheme 24: Nanocatalytic protocol proposed by Kaur et al.
Scheme 25: Microwave approach introduced by Yuan.
Scheme 26: Microwave approach introduced by Zahran et al.
Scheme 27: Microwave irradiation protocol introduced by Bindu.
Scheme 28: Silica-supported microwave irradiation protocol.
Scheme 29: Proposed mechanism for formation of BIM by Nongkhlaw.
Scheme 30: Microwave-assisted synthesis of BIMs catalyzed by succinic acid.
Scheme 31: Proposed mechanism of action of MMO-4.
Scheme 32: Catalytic approach introduced by Muhammadpoor-Baltork et al.
Scheme 33: Reaction conditions used by Xiao-Ming.
Scheme 34: Ultrasonic irradiation-based protocol published by Saeednia.
Scheme 35: Pyruvic acid-mediated synthesis of BIMs proposed by Thopate.
Scheme 36: Synthesis of BIMs using [bmim]BF4 or [bmim]PF6 ionic liquids.
Scheme 37: Synthesis of BIMs utilizing In(OTf)3 in octylmethylimidazolium hexafluorophosphate as ionic liquid.
Scheme 38: FeCl3·6H2O-catalyzed synthesis of BIMs with use of ionic liquid.
Scheme 39: Synthesis of BIMs utilizing the [hmim]HSO4/EtOH catalytic system.
Scheme 40: Synthesis of BIMs utilizing acidic ionic liquid immobilized on silica gel (ILIS-SO2Cl).
Scheme 41: The [bmim][MeSO4]-catalyzed reaction of indole with various aldehydes.
Scheme 42: The role of [bmim][MeSO4] in catalyzing the reaction of indole with aldehydes.
Scheme 43: Synthesis of BIMs utilizing FeCl3-based ionic liquid ([BTBAC]Cl-FeCl3) as catalyst.
Scheme 44: Synthesis of BIMs using [Msim]Cl at room temperature.
Scheme 45: [Et3NH][H2PO4]-catalyzed synthesis of bis(indolyl)methanes.
Scheme 46: PILs-catalyzed synthesis of bis(indolyl)methanes.
Scheme 47: FSILs-mediated synthesis of bis(indolyl)methanes.
Scheme 48: Possible “release and catch” catalytic process.
Scheme 49: Synthesis of bis(indolyl)methanes by [DABCO-H][HSO4].
Scheme 50: Synthesis of bis(indolyl)methanes by [(THA)(SO4)].
Scheme 51: Synthesis of BBSI-Cl and BBSI-HSO4.
Scheme 52: Synthesis of BIMs in the presence of BBSI-Cl and BBSI-HSO4.
Scheme 53: Chemoselectivity of the present method.
Scheme 54: Synthesis of BIMs catalyzed by chitosan-supported ionic liquid.
Scheme 55: Proposed mechanism of action of CSIL.
Scheme 56: Optimization of the reaction in DESs.
Scheme 57: Synthesis of BIMs using ChCl/SnCl2 as DES.
Scheme 58: Synthesis of BIMs derivatives in presence of DES.
Scheme 59: BIMs synthesis in choline chloride/urea (CC/U).
Scheme 60: Flow chemistry-based synthesis of BIMs by Ley.
Scheme 61: Flow chemistry-based synthesis of BIMs proposed by Nam et al.
Scheme 62: Amino-catalyzed reaction of indole with propionaldehyde.
Scheme 63: Aminocatalytic synthesis of BIMs.
Scheme 64: Proposed mechanism for the aminocatalytic synthesis of BIMs.
Scheme 65: Enzymatic reaction of indole with aldehydes.
Scheme 66: Proposed mechanism for the synthesis of BIMs catalyzed by TLIM.
Scheme 67: Proposed reaction mechanism by Badsara.
Scheme 68: Mechanism proposed by D’Auria.
Scheme 69: Photoinduced thiourea catalysis.
Scheme 70: Proposed mechanism of photoacid activation.
Scheme 71: Proposed mechanism of action for CF3SO2Na.
Scheme 72: Proposed mechanism for the synthesis of BIMs by Mandawad.
Scheme 73: Proposed mechanism for the (a) acid generation and (b) synthesis of BIMs.
Scheme 74: a) Reaction conditions employed by Khaksar and b) activation of the carbonyl group by HFIP.
Scheme 75: Activation of the carbonyl group by the PPy@CH2Br through the formation of a halogen bond.
Scheme 76: Reaction conditions utilized by Mhaldar et al.
Scheme 77: a) Reaction conditions employed by López and b) activation of the carbonyl group by thiourea.
Scheme 78: Infrared irradiation approach introduced by Luna-Mora and his research group.
Scheme 79: Synthesis of BIMs with the use of the Fe–Zn BMOF.
Elucidating the glycan-binding specificity and structure of Cucumis melo agglutinin, a new R-type lectin
- Jon Lundstrøm,
- Emilie Gillon,
- Valérie Chazalet,
- Nicole Kerekes,
- Antonio Di Maio,
- Ten Feizi,
- Yan Liu,
- Annabelle Varrot and
- Daniel Bojar
Beilstein J. Org. Chem. 2024, 20, 306–320, doi:10.3762/bjoc.20.31
- interaction with the aromatic ring of Tyr26 (Figure 4c). Further, beyond the C2 position of galactose, a cavity filled with coordinated water molecules hinted at the binding mode for C2-substituted galactose. Notably, the seemingly inactive beta site was found to be occupied by a cadmium ion (Figure S4
- equilibrium, n = 2. Structural insights into the binding mechanism of CMA1. (a, b) Overall representation of the N-terminal domain of CMA1 in complex with (a) LacNAc (Galβ1-4GlcNAc) [29] or (b) GalNAc [30]. Trefoil repeats are colored differently, and cadmium ions are represented as red spheres. (c, d) Close
Graphical Abstract
Figure 1: Characterizing a new lectin from the melon Cucumis melo. (a) Evolutionary relationships of common R...
Figure 2: Characterizing the binding specificity of CMA1. (a, b) Lectin produced in mammalian cells was analy...
Figure 3: Assessing and quantifying in-solution binding of CMA1. (a) Erythrocyte agglutination assay. Using r...
Figure 4: Structural insights into the binding mechanism of CMA1. (a, b) Overall representation of the N-term...
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
- -Pb, wherein the metal centre is coordinated through four nitrogen donors and only weakly interacts with two oxygen atoms of the ether segments (Figure 15). Once crownphyrins reacted with geometrically more demanding than Pb(II) metals, i.e., zinc(II), cadmium(II), and mercury(II), they initially
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.
Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis
- Prodip Howlader and
- Michael Schmittel
Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62
- metal–ligand motifs often center about iridium, ruthenium, rhodium etc. [25], the dynamic ones are constructed using copper(I), zinc(II), cadmium(II), iron(II), palladium(II), etc. as metal ions due to their more rapid ligand exchange rates [24][25][26]. The strategies to prepare inert vs dynamic
- , since a variety of heteroleptic aggregation protocols have been developed by Schmittel [37] (for copper(I), zinc(II), cadmium(II), mercury(II) ions) and Yoshizawa/Fujita [38] (for palladium(II) ion) that involve pyridine-derived ligands. Highly innovative are the approaches for terpyridine-based
Graphical Abstract
Figure 1: Butterfly 1 (Figure was reprinted with permission from [45]. Copyright 2012 American Chemical Society. ...
Figure 2: Synthesis of the three-component heteroleptic molecular boat 8 and its use as a catalyst for the Kn...
Figure 3: Synthesis of the two-component triangle 14 and three-component heteroleptic prism 15 [59]. Figure was a...
Figure 4: Catalytic Michael addition reaction using the urea-decorated molecular prism 15 [59].
Figure 5: Self-assembly of two-component tetragonal prismatic architectures with different cavity size. Figur...
Figure 6: Construction of artificial LHS using rhodamine B as an acceptor and 24b as donor generating a photo...
Figure 7: Synthesis of supramolecular spheres with varying [AuCl] concentration inside the cavity. Figure was...
Figure 8: Hydroalkoxylation reaction of γ-allenol 34 in the presence of [AuCl]-encapsulated molecular spheres ...
Figure 9: Two-component heteroleptic triangles of different size containing a BINOL functionality. Figure was...
Figure 10: Asymmetric conjugate addition of chalcone 42 with trans-styrylboronic acid (43) catalyzed by BINOL-...
Figure 11: Encapsulation of monophosphoramidite-Rh(I) catalyst into a heteroleptic tetragonal prismatic cage 47...
Figure 12: (a) Representations of the basic HETPYP, HETPHEN, and HETTAP complex motifs. (b) The three-componen...
Figure 13: Two representative four-component rotors, with a (top) two-arm stator and (bottom) a four-arm stato...
Figure 14: Four-component rotors with a monohead rotator. Figure was adapted with permission from [94]. Copyright ...
Figure 15: (left) Click reaction catalyzed by rotors [Cu2(55)(60)(X)]2+. (right) Yield as a function of the ro...
Figure 16: A supramolecular AND gate. a) In truth table state (0,0) two nanoswitches serve as the receptor ens...
Figure 17: Two supramolecular double rotors (each has two rotational axes) and reference complex [Cu(78)]+ for...
Figure 18: The slider-on-deck system (82•X) (X = 83, 84, or 85). Figure is from [98] and was reprinted from the jo...
Figure 19: Catalysis of a conjugated addition reaction in the presence of the slider-on-deck system (82•X) (X ...
Figure 20: A rotating catalyst builds a catalytic machinery. For catalysis of the catalytic machinery, see Figure 21. F...
Figure 21: Catalytic machinery. Figure was adapted from [100] (“Evolution of catalytic machinery: three-component n...
Figure 22: An information system based on (re)shuffling components between supramolecular structures [99]. Figure ...
Figure 23: Switching between dimeric heteroleptic and homoleptic complex for OFF/ON catalytic formation of rot...
Figure 24: A chemically fueled catalytic system [112]. Figure was adapted from [112]. Copyright 2021 American Chemical S...
Figure 25: (Top) Operation of a fuel acid. (Bottom) Knoevenagel addition [112].
Figure 26: Development of the yield of Knoevenagel product 118 in a fueled system [112]. Figure was reprinted with ...
Figure 27: Weak-link strategy to increased catalytic activity in epoxide opening [119]. Figure was adapted from [24]. C...
Figure 28: A ON/OFF polymerization switch based on the weak-link approach [118]. Figure was reprinted with permissi...
Figure 29: A weak-link switch turning ON/OFF a Diels–Alder reaction [132]. Figure was reprinted with permission fro...
Figure 30: A catalyst duo allowing selective activation of one of two catalytic acylation reactions [133] upon subs...
Figure 31: A four-state switchable nanoswitch (redrawn from [134]).
Figure 32: Sequential catalysis as regulated by nanoswitch 138 and catalyst 139 in the presence of metal ions ...
Figure 33: Remote control of ON/OFF catalysis administrated by two nanoswitches through ion signaling (redrawn...
The preparation and properties of 1,1-difluorocyclopropane derivatives
- Kymbat S. Adekenova,
- Peter B. Wyatt and
- Sergazy M. Adekenov
Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25
- -dimethoxyethane (Scheme 20) [60]. The difluorocarbene then added to cyclohexene (49) to form difluoronorcarane 50 with good yield. Under similar conditions tetramethylethylene afforded 1,1-difluorotetramethylcyclopropane (4). Trifluoromethyl derivatives of cadmium, bismuth, zinc, and gold: Bis(trifluoromethyl
- )cadmium (51) precipitates quantitatively as a white powder from the reaction of CF3I with Cd(Et)2 (molar ratio 2.5:1) (Scheme 21) in chloroform at −40 °C. A warming to −5 °C was sufficient to liberate difluorocarbene, which was trapped by the addition to alkenes. Thus, cis-stilbene (52) gave the gem
- -difluorocyclopropane derivative 53 plus cadmium fluoride [61][62]. However, cadmium compounds are highly toxic and furthermore (CF3)2Cd is pyrophoric in air and liable to explode upon warming to room temperature. Tris(trifluoromethyl)bismuth (54) is also a source of difluorocarbene, that is generated during the
Graphical Abstract
Scheme 1: Synthesis of 1,1-difluoro-2,3-dimethylcyclopropane (2).
Scheme 2: Cyclopropanation via dehydrohalogenation of chlorodifluoromethane.
Scheme 3: Difluorocyclopropanation of methylstyrene 7 using dibromodifluoromethane and zinc.
Scheme 4: Synthesis of difluorocyclopropanes from the reaction of dibromodifluoromethane and triphenylphosphi...
Scheme 5: Generation of difluorocarbene in a catalytic two-phase system and its addition to tetramethylethyle...
Scheme 6: The reaction of methylstyrene 7 with chlorodifluoromethane (11) in the presence of a tetraarylarson...
Scheme 7: Pyrolysis of sodium chlorodifluoroacetate (12) in refluxing diglyme in the presence of alkene 13.
Scheme 8: Synthesis of boron-substituted gem-difluorocyclopropanes 16.
Scheme 9: Addition of sodium bromodifluoroacetate (17) to alkenes.
Scheme 10: Addition of sodium bromodifluoroacetate (17) to silyloxy-substituted cyclopropanes 20.
Scheme 11: Synthesis of difluorinated nucleosides.
Scheme 12: Addition of butyl acrylate (26) to difluorocarbene generated from TFDA (25).
Scheme 13: Addition of difluorocarbene to propargyl esters 27 and conversion of the difluorocyclopropenes 28 t...
Scheme 14: The generation of difluorocyclopropanes using MDFA 30.
Scheme 15: gem-Difluorocyclopropanation of styrene (32) using difluorocarbene generated from TMSCF3 (31) under...
Scheme 16: Synthesis of a gem-difluorocyclopropane derivative using HFPO (41) as a source of difluorocarbene.
Scheme 17: Cyclopropanation of (Z)-2-butene in the presence of difluorodiazirine (44).
Scheme 18: The cyclopropanation of 1-octene (46) using Seyferth's reagent (45) as a source of difluorocarbene.
Scheme 19: Alternative approaches for the difluorocarbene synthesis from trimethyl(trifluoromethyl)tin (48).
Scheme 20: Difluorocyclopropanation of cyclohexene (49).
Scheme 21: Synthesis of difluorocyclopropane derivative 53 using bis(trifluoromethyl)cadmium (51) as the diflu...
Scheme 22: Addition of difluorocarbene generated from tris(trifluoromethyl)bismuth (54).
Scheme 23: Addition of a stable (trifluoromethyl)zinc reagent to styrenes.
Scheme 24: The preparation of 2,2-difluorocyclopropanecarboxylic acids of type 58.
Scheme 25: Difluorocyclopropanation via Michael cyclization.
Scheme 26: Difluorocyclopropanation using N-acylimidazolidinone 60.
Scheme 27: Difluorocyclopropanation through the cyclization of phenylacetonitrile (61) and 1,2-dibromo-1,1-dif...
Scheme 28: gem-Difluoroolefins 64 for the synthesis of functionalized cyclopropanes 65.
Scheme 29: Preparation of aminocyclopropanes 70.
Scheme 30: Synthesis of fluorinated methylenecyclopropane 74 via selenoxide elimination.
Scheme 31: Reductive dehalogenation of (1R,3R)-75.
Scheme 32: Synthesis of chiral monoacetates by lipase catalysis.
Scheme 33: Transformation of (±)-trans-81 using Rhodococcus sp. AJ270.
Scheme 34: Transformation of (±)-trans-83 using Rhodococcus sp. AJ270.
Scheme 35: Hydrogenation of difluorocyclopropenes through enantioselective hydrocupration.
Scheme 36: Enantioselective transfer hydrogenation of difluorocyclopropenes with a Ru-based catalyst.
Scheme 37: The thermal transformation of trans-1,2-dichloro-3,3-difluorocyclopropane (84).
Scheme 38: cis–trans-Epimerization of 1,1-difluoro-2,3-dimethylcyclopropane.
Scheme 39: 2,2-Difluorotrimethylene diradical intermediate.
Scheme 40: Ring opening of stereoisomers 88 and 89.
Scheme 41: [1,3]-Rearrangement of alkenylcyclopropanes 90–92.
Scheme 42: Thermolytic rearrangement of 2,2-difluoro-1-vinylcyclopropane (90).
Scheme 43: Thermal rearrangement for ethyl 3-(2,2-difluoro)-3-phenylcyclopropyl)acrylates 93 and 95.
Scheme 44: Possible pathways of the ring opening of 1,1-difluoro-2-vinylcyclopropane.
Scheme 45: Equilibrium between 1,1-difluoro-2-methylenecyclopropane (96) and (difluoromethylene)cyclopropane 97...
Scheme 46: Ring opening of substituted 1,1-difluoro-2,2-dimethyl-3-methylenecyclopropane 98.
Scheme 47: 1,1-Difluorospiropentane rearrangement.
Scheme 48: Acetolysis of (2,2-difluorocyclopropyl)methyl tosylate (104) and (1,1-difluoro-2-methylcyclopropyl)...
Scheme 49: Ring opening of gem-difluorocyclopropyl ketones 106 and 108 by thiolate nucleophiles.
Scheme 50: Hydrolysis of gem-difluorocyclopropyl acetals 110.
Scheme 51: Ring-opening reaction of 2,2-difluorocyclopropyl ketones 113 in the presence of ionic liquid as a s...
Scheme 52: Ring opening of gem-difluorocyclopropyl ketones 113a by MgI2-initiated reaction with diarylimines 1...
Scheme 53: Ring-opening reaction of gem-difluorocyclopropylstannanes 117.
Scheme 54: Preparation of 1-fluorovinyl vinyl ketone 123 and the synthesis of 2-fluorocyclopentenone 124. TBAT...
Scheme 55: Iodine atom-transfer ring opening of 1,1-difluoro-2-(1-iodoalkyl)cyclopropanes 125a–c.
Scheme 56: Ring opening of bromomethyl gem-difluorocyclopropanes 130 and formation of gem-difluoromethylene-co...
Scheme 57: Ring-opening aerobic oxidation reaction of gem-difluorocyclopropanes 132.
Scheme 58: Dibrominative ring-opening functionalization of gem-difluorocyclopropanes 134.
Scheme 59: The selective formation of (E,E)- and (E,Z)-fluorodienals 136 and 137 from difluorocyclopropyl acet...
Scheme 60: Proposed mechanism for the reaction of difluoro(methylene)cyclopropane 139 with Br2.
Scheme 61: Thermal rearrangement of F2MCP 139 and iodine by CuI catalysis.
Scheme 62: Synthesis of 2-fluoropyrroles 142.
Scheme 63: Ring opening of gem-difluorocyclopropyl ketones 143 mediated by BX3.
Scheme 64: Lewis acid-promoted ring-opening reaction of 2,2-difluorocyclopropanecarbonyl chloride (148).
Scheme 65: Ring-opening reaction of the gem-difluorocyclopropyl ketone 106 by methanolic KOH.
Scheme 66: Hydrogenolysis of 1,1-difluoro-3-methyl-2-phenylcyclopropane (151).
Scheme 67: Synthesis of monofluoroalkenes 157.
Scheme 68: The stereoselective Ag-catalyzed defluorinative ring-opening diarylation of 1-trimethylsiloxy-2,2-d...
Scheme 69: Synthesis of 2-fluorinated allylic compounds 162.
Scheme 70: Pd-catalyzed cross-coupling reactions of gem-difluorinated cyclopropanes 161.
Scheme 71: The (Z)-selective Pd-catalyzed ring-opening sulfonylation of 2-(2,2-difluorocyclopropyl)naphthalene...
Figure 1: Structures of zosuquidar hydrochloride and PF-06700841.
Scheme 72: Synthesis of methylene-gem-difluorocyclopropane analogs of nucleosides.
Figure 2: Anthracene-difluorocyclopropane hybrid derivatives.
Figure 3: Further examples of difluorcyclopropanes in modern drug discovery.
Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands
- Jennifer Klose,
- Tobias Severin,
- Peter Hahn,
- Alexander Jeremies,
- Jens Bergmann,
- Daniel Fuhrmann,
- Jan Griebel,
- Bernd Abel and
- Berthold Kersting
Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81
- with λ = 365 nm reveals a photoisomerization of the co-ligand from the trans to the cis form. Keywords: azobenzene carboxylates; cadmium; complexes; macrocyclic ligands; nickel; zinc; Introduction The macrocyclic N6S2 donor ligand H2L is an effective dinucleating ligand that supports a large number
- cadmium complexes 1, 6 and 8, on the other hand, were prepared by substitution reactions involving the known chlorido-bridged [Ni2L(μ-Cl)]+ or [Cd2L(μ-Cl)]+ precursors and the respective azobenzene carboxylates. All complexes were isolated as ClO4− salts with yields between 76% and 91%. The perchlorate
- determine their structures in solution the diamagnetic zinc and cadmium complexes were subjected to 1H and 13C NMR spectroscopic studies. Table 2, and Tables S4 and S5 (Supporting Information File 1) list the 1H and 13C NMR spectroscopic data for complexes 1, 3, 5, 6 and 8. The data for [Zn2L(μ-OAc)]+ and
Graphical Abstract
Figure 1: Left: Mixed ligand complexes of the type [M2L(μ-L')]n+ supported by the macrocyclic ligand H2L (M =...
Figure 2: Synthesized compounds and their labels.
Scheme 1: Synthesis of complexes 1–9.
Figure 3: 1H NMR spectrum of 6 in CD3CN at 295 K (1.0–8.0 ppm). The resonances and assignments are listed in Table 2...
Figure 4: Structure of the [Zn2L(μ-azo-OH)]+ cation in crystals of [Zn2L(μ-azo-OH)][Zn2L(μ-azo-O)]·4MeCN·3H2O...
Figure 5: Space filling representation of the packing of two symmetry-related [Zn2L(μ-azo-NMe2)]+ cations in ...
Figure 6: Structure of the [Cd2L(μ-azo-NMe2)]+ cation in crystals of [Cd2L(μ-azo-NMe2)]ClO4·0.5MeOH (6·0.5MeO...
Figure 7: Space filling representation of the packing of four [Cd2L(μ-azo-NMe2)]+ cations in crystals of 6·0....
Figure 8: Structures of the two crystallographically independent [Ni2L(μ-azo-NMe2)]+ cations A (left) and B (...
Figure 9: Left: ORTEP representation of the molecular structure of the [Cd2L(μ-azo-CO2Me)]+ cation in crystal...
Figure 10: Plots of the effective magnetic moment μeff for 2 (open circles), 4 (open squares), and 7 (open tri...
Figure 11: UV–vis spectra of Hazo-H (red line), [Cd2L(μ-Cl)](ClO4) (black line) and [Cd2L(μ-azo-H)]ClO4 (1, bl...
Figure 12: UV–vis spectra of Hazo-NMe2 (red line), [Ni2L(μ-Cl)](ClO4) (black line) and [Ni2L(μ-azo-NMe2)]ClO4 (...
Figure 13: UV–vis spectra of solutions of [Cd2L(μ-azo-H)]ClO4 (1) in acetonitrile irradiated with a UV LED lam...
Scheme 2: Cis/trans isomerization process of the bound azo-carboxylato co-ligand in [Cd2L(μ-azo-H)]ClO4 (1) i...
Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles
- Dennis Hiltrop,
- Steffen Cychy,
- Karina Elumeeva,
- Wolfgang Schuhmann and
- Martin Muhler
Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120
- layer configuration, where the thickness of the thin layer is tunable in the micrometer range by an implemented micrometer screw. The Bruker Tensor 27 FTIR spectrometer was equipped with an A530/P reflection unit, a liquid nitrogen mercury cadmium telluride detector and was constantly purged with dried
Graphical Abstract
Figure 1: CVs of the electrooxidation of 1 M glycerol over Pd/NCNT and Pd/OCNT in 1 M KOH at 1000 rpm at a sc...
Figure 2: CVs of the electrooxidation of 1 M glycerol over Pd/NCNT-NH3 and Pd/OCNT-He in 1 M NaOH at 1000 rpm...
Figure 3: Comparison of IR spectra recorded at 0.77 and 1.17 V vs RHE (further potentials are shown in Supporting Information File 1, Figu...
Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface
- Frederik Neuhaus,
- Fabio Zobi,
- Gerald Brezesinski,
- Marta Dal Molin,
- Stefan Matile and
- Andreas Zumbuehl
Beilstein J. Org. Chem. 2017, 13, 1099–1105, doi:10.3762/bjoc.13.109
- ) equipped with a liquid nitrogen cooled MCT (mercury cadmium telluride) detector attached to an external air/water reflection unit (XA-511). The IR beam was conducted out of the spectrometer and focused onto the water surface of the thermostated Langmuir trough. The measurements were carried out with p- and
Graphical Abstract
Figure 1: Structure of the (bis)dithienothiophene mechanosensitive flipper probe. Twisted out of planarity by...
Figure 2: Langmuir–Pockels isotherm of a monolayer of flipper mechanophores during the first compression (bla...
Figure 3: OH-stretching vibration (ν(OH); 3600 cm−1) for IRRA spectra of a flipper mechanophore monolayer dur...
Figure 4: Isotherms of DPPC (dark blue), cholesterol (magenta), DPPC/cholesterol (8:2 mol/mol, green), and DP...
Figure 5: Correlation of the hue of a monolayer flipper probe with its measured surface pressure at the water...
Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications
- Stephen Hill and
- M. Carmen Galan
Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67
- fluorophores, in addition to bright visible emission, have become particularly popular for their versatility as non-isotopic detection labels which are amenable to live cell imaging and immunoassay applications [7]. In particular, cadmium-based QDs (e.g., CdS, CdSe, CdSe/ZnS) are commonly used for in vitro
Graphical Abstract
Scheme 1: Microwave-driven reaction of glucose in the presence of PEG-200 to afford blue-emissive CDs.
Scheme 2: Two-step synthesis of TTDDA-coated CDs generated from acid-refluxed glucose.
Scheme 3: Glucose-derived CDs using KH2PO4 as a dehydrating agent to both form and tune CD’s properties.
Scheme 4: Ultrasonic-mediated synthesis of glucose-derived CDs in the presence of ammonia.
Scheme 5: Tryptophan-derived CDs used for the sensing of peroxynitrite in serum-fortified cell media.
Scheme 6: Glucose-derived CDs conjugated with methotrexate for the treatment of H157 lung cancer cells.
Scheme 7: Boron-doped blue-emissive CDs used for sensing of Fe3+ ion in solution.
Scheme 8: N/S-doped CDs with aggregation-induced fluorescence turn-off to temperature and pH stimuli.
Scheme 9: N/P-doped hollow CDs for efficient drug delivery of doxorubicin.
Scheme 10: N/P-doped CDs applied to the sensing of Fe3+ ions in mammalian T24 cells.
Scheme 11: Comparative study of CDs formed from glucose and N-doped with TTDDA and dopamine.
Scheme 12: Formation of blue-emissive CDs from the microwave irradiation of glycerol, TTDDA and phosphate.
Scheme 13: Xylitol-derived N-doped CDs with excellent photostability demonstrating the importance of Cl incorp...
Scheme 14: Base-mediated synthesis of CDs with nanocrystalline cores, from fructose and maltose, without forci...
Scheme 15: N/P-doped green-emissive CDs working in tandem with hyaluronic acid-coated AuNPs to monitor hyaluro...
Scheme 16: Three-minute microwave synthesis of Cl/N-doped CDs from glucosamine hydrochloride and TTDDA to affo...
Scheme 17: Mechanism for the formation of N/Cl-doped CDs via key aldehyde and iminium intermediates, monitored...
Scheme 18: Phosphoric acid-mediated synthesis of orange-red emissive CDs from sucrose.
Scheme 19: Proposed HMF dimer, and its formation mechanism, that upon aggregations bestows orange-red emissive...
Scheme 20: Different polysaccharide-derived CDs in the presence of PEG-200 and how the starting material compo...
Scheme 21: Tetracycline release profiles for differentially-decorated CDs.
Scheme 22: Hyaluronic acid (HA) and glycine-derived CDs, suspected to be decorated in unreacted HA, allowing r...
Scheme 23: Cyclodextrin-derived CDs used for detection of Ag+ ions in solution, based on the formal reduction ...
Scheme 24: Cyclodextrin and OEI-derived CDs, coated with hyaluronic acid and DOX, to produce an effective lung...
Scheme 25: Cellulose and urea-derived N-doped CDs with green-emissive fluorescence.
Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines
- Adrian E. Ion,
- Liliana Cristian,
- Mariana Voicescu,
- Masroor Bangesh,
- Augustin M. Madalan,
- Daniela Bala,
- Constantin Mihailciuc and
- Simona Nica
Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171
- + structural motif. A similar visible-change profile was observed in the case of CdCl2 titration, but here the analysis of the titration curve showed a different profile (Figure 9). First, a closer look at the resulting UV–vis spectrum after cadmium(II) complex formation shows that the absorption maximum is
- shows the visible absorption changes upon mercury binding. Absorption spectra of a 4.26 mM solution of 4a in methanol upon titration with CdCl2 aqueous solution (0–1.0 equivalents). Inset shows the visible absorption changes upon cadmium binding. Synthesis of 4′-azulenyl substituted terpyridines
Graphical Abstract
Scheme 1: Synthesis of 4′-azulenyl substituted terpyridines.
Figure 1: Molecular structure and numbering scheme of 4′-(1-azulenyl)-2,2′:6′,2″-terpyridine (4a, left) and 4...
Figure 2: Packing diagram for 4a showing the π–π stacking and CH–π interactions between the pyridine rings an...
Figure 3: Packing diagram for 4b showing the π–π stacking between the pyridine rings. Hydrogen atoms are omit...
Figure 4: Absorption spectra of the azulene-containing terpyridine, 4a and 4b in CH2Cl2 solution at room temp...
Figure 5: Emission spectra of the azulene-containing terpyridine, 4a and 4b in CH2Cl2 solution (2.59 × 10−5 M...
Figure 6: Selected Kohn–Sham orbitals and orbital energies for 4a and 4b, obtained with three different funct...
Figure 7: DPV-traces (with baseline correction) of 0.5 mM solutions of 4a (solid) and 4b (dash) in DMF, with ...
Figure 8: Absorption spectra of a 4.26 mM solution of 4a in methanol upon titration with an aqueous HgCl2 sol...
Figure 9: Absorption spectra of a 4.26 mM solution of 4a in methanol upon titration with CdCl2 aqueous soluti...
Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series
- Cécile Verrier,
- Pierrik Lassalas,
- Laure Théveau,
- Guy Quéguiner,
- François Trécourt,
- Francis Marsais and
- Christophe Hoarau
Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187
- ], manganate ((Me3SiCH2)2Mn(TMP)Li·TMEDA) [3][8], cuprates (MeCu(TMP)(CN)Li2, (TMP)2CuLi) [9][10] and cadmium amides ((TMP)3CdLi) [11][12], for regio- and/or chemoselective deprotonative metalation of aromatics, producing arylmetal intermediates under smooth reaction conditions that are directly suitable for
Graphical Abstract
Scheme 1: Stoichiometric and catalytic direct (hetero)arylation of arenes.
Scheme 2: Stille and Negishi cross-coupling methodologies in oxazole series [28,30,31,33,34].
Scheme 3: Stoichiometric direct (hetero)arylation of (benz)oxazole with magnesate bases [35].
Scheme 4: Ohta's pioneering catalytic direct C5-selective pyrazinylation of oxazole [36,37].
Scheme 5: Preparation of pharmaceutical compounds by following the pioneering Ohta protocol [38,39].
Scheme 6: Miura’s pioneering catalytic direct arylations of (benz)oxazoles [40]. aIsolated yield.
Scheme 7: Pd(0)- and Cu(I)-catalyzed direct C2-selective arylation of (benz)oxazoles [41-44].
Scheme 8: Cu(I)-catalyzed direct C2-selective arylations of (benz)oxazoles [40,45-47].
Scheme 9: Copper-free Pd(0)-catalyzed direct C5- and C2-selective arylation of oxazole-4-carboxylate esters [48-50,52].
Scheme 10: Iterative synthesis of bis- and trioxazoles [51].
Scheme 11: Preparation of DPO- and POPOP-analogues [53].
Scheme 12: Pd(0)-catalyzed direct arylation of benzoxazole with aryl chlorides [54].
Scheme 13: Pd(0)-catalyzed direct C2-selective arylation of (benz)oxazoles with bromides and chlorides using b...
Scheme 14: Palladium-catalyzed direct arylation of oxazoles under green conditions; (a) Zhuralev direct arylat...
Scheme 15: Pd(0)-catalyzed C2- and C5-selective (hetero)arylation of oxazole [63].
Scheme 16: Pd(0)-catalyzed C2- and C5-selective (hetero)arylation of ethyl oxazole-4-carboxylate [64].
Scheme 17: Pd(0)-catalyzed direct C4-phenylation of oxazoles; (a) Miura’s procedure [65]; (b) Fagnou’s procedure [66].
Scheme 18: Catalytic cycles for Cu(I)-catalyzed (routeA) and Pd(0)/Cu(I)-catalyzed (route B) direct arylation ...
Scheme 19: Base-assisted, Pd(0)-catalyzed, C2-selective, direct arylation of benzoxazole proposed by Zhuralev [58]...
Scheme 20: Electrophilic substitution-type mechanism proposed by Hoarau [64].
Scheme 21: CMD-proceeding C5-selective direct arylation of oxazole proposed by Strotman and Chobabian [63].
Scheme 22: DFT calculations on methyl oxazole-4-carboxylate and consequently developed methodologies for the P...
Scheme 23: Pd(0)-catalyzed direct arylation of (benz)oxazoles with tosylates and mesylates [71].
Scheme 24: Pd(0)-catalyzed direct arylation of oxazoles with sulfamates [72].
Scheme 25: Pd(II)- and Cu(II)-catalyzed decarboxylative direct C–H coupling of oxazoles with 4- and 5-carboxyo...
Scheme 26: Pd(II)- and Ag(II)-catalyzed decarboxylative direct arylation of (benzo)oxazoles [74]; (a) procedure; (...
Scheme 27: Pd(II)- and Cu(II)-catalyzed direct arylation of benzoxazole with arylboronic acids [76]; (a) procedure...
Scheme 28: Ni(II)-catalyzed direct arylation of benzoxazoles with arylboronic acids under O2 [76]; (a) procedure; ...
Scheme 29: Rhodium-catalyzed direct arylation of benzoxazole [78,79].
Scheme 30: Ni(II)-catalyzed direct arylation of (benz)oxazoles with aryl halides; (a) Itami's procedure [80]; (b) ...
Scheme 31: Dehydrogenative cross-coupling of (benz)oxazoles; (a) Pd(II)- and Cu(II)-catalyzed cross-coupling o...
Ratiometric fluorescent probe for enantioselective detection of D-cysteine in aqueous solution
- Xiao-bo Zhou,
- Wing-Hong Chan,
- Albert W. M. Lee and
- Chi-Chung Yeung
Beilstein J. Org. Chem. 2011, 7, 1508–1515, doi:10.3762/bjoc.7.176
- cadmium complex (Cd2+–ACAQ) can induce a distinctive ratiometric fluorescence change characterized by the formation of an obvious isoemissive point at 450 nm (Figure 3b). We envisioned that the strong binding affinity of cysteine to Cd2+ perturbs its interaction with ACAQ in such a way that the ICT
- Cd2+–ACAQ. As cadmium is well-known for its strong affinity to sulfur-containing compounds, we envisioned that the Cd2+-bound ACAQ complex would demonstrate chemoselective binding toward amino acids. Among 22 amino acids, a tripeptide, cysteine derivative and β-mercaptopropionic acid (MPA), only Cys
- ). Considering the fact that Cys is a trifunctional amino acid, it is interesting to unravel its binding mode with the cadmium-centred fluorescent chemosensor ACAQ. To shed light on the binding mechanism of Cys with the probe, seven other sulfur-containing molecules were chosen as control compounds (Table 3
Graphical Abstract
Figure 1: Structures of biological active thiols.
Figure 2: The structure of ACAQ.
Figure 3: Emission spectra of (a) Zn2+–ACAQ or (b) Cd2+–ACAQ complex (5 μM) at increasing concentrations of C...
Figure 4: Job’s plot of Cd2+–ACAQ in 10 mM HEPES buffer (pH 7.4) at 298 K. The sum of the concentrations of t...
Figure 5: Fluorescence spectra of Cd2+–ACAQ (10 µm) upon the titration of (a) D-Cys and (b) L-Cys in buffer s...
Figure 6: Fluoresence emission change of Cd2+–ACAQ at 500 nm in response to the addition of 15 equiv amino ac...
Figure 7: Fluorescence spectra of (10 µm) Cd2+–ACAQ upon the titration of various amino acids in buffer solut...
Figure 8: UV spectra of Cd2+–ACAQ (25 µm) upon the titration of (a) D-Cys, (b) L-Cys (0–12 equiv) in buffer s...
Figure 9: Partial 1H NMR spectra (400 MHz) of ACAQ (5 mM) before and after the addition of Cd2+ and then incr...
Figure 10: Proposed binding model of Cd2+–ACAQ with cysteine.
Figure 11: Reversibility study. Emission spectra of Cd2+–ACAQ complex (5 μM) with 10 equiv L-Cys in buffer sol...
Photocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies
- Axel G. Griesbeck,
- Marco Franke,
- Jörg Neudörfl and
- Hidehiro Kotaka
Beilstein J. Org. Chem. 2011, 7, 127–134, doi:10.3762/bjoc.7.18
- dropwise to a solution of cadmium chloride (18.30 g) in water (15 mL). The resulting precipitate was filtered, washed with a little cold water and dried. The resulting solid was then suspended in water, heated to boiling and a mixture of isoxazole and water was obtained on distillation. The distillate (two
Graphical Abstract
Scheme 1: Synthetic routes to isoxazoles 7a–7e.
Scheme 2: Synthetic routes to isoxazoles 7f–7h.
Scheme 3: Benzaldehyde photocycloaddition to 7a–7e.
Scheme 4: Photochemical ring contraction of isoxazoles 7f–7h.
Scheme 5: Photocycloaddition of aromatic aldehydes to di- and trimethyl isoxazoles 7d and 7e.
Scheme 6: Preparative photocycloadditions of 7e with aromatic aldehydes.
Figure 1: Structures of the photoproducts 9a–9c in the crystal.
Scheme 7: T-type photochromism of isoxazole–aldehyde pairs.
Scheme 8: Reductive cleavage of the trimethylisoxazole adduct 9a.
