Search results
Search for "lipid" in Full Text gives 141 result(s) in Beilstein Journal of Organic Chemistry.
Modulating the activity of short arginine-tryptophan containing antibacterial peptides with N-terminal metallocenoyl groups
- H. Bauke Albada,
- Alina-Iulia Chiriac,
- Michaela Wenzel,
- Maya Penkova,
- Julia E. Bandow,
- Hans-Georg Sahl and
- Nils Metzler-Nolte
Beilstein J. Org. Chem. 2012, 8, 1753–1764, doi:10.3762/bjoc.8.200
- activities of these RW-based synAMPs and their organometallic conjugates into perspective, two reference peptides were included, i.e., membrane-targeting gramicidin S derivative GS(K2Y2) and cell wall precursor lipid II-targeting vancomycin. For the calculations of the MIC values in µM, molecular weights of
- ) and their metallocene-derivatives (right); the lower row shows the structure of pore-forming gramicidin S derivative GS(K2Y2) (left) and lipid II-binding cell wall biosynthesis inhibitor vancomycin (right). Bactericidal activity of (RW)3 against S. aureus 133 (panel A and D) or B. megaterium (panel B
Graphical Abstract
Figure 1: Structures of the most active peptides that have been used in this study. The top row shows two rep...
Figure 2: Bactericidal activity of (RW)3 against S. aureus 133 (panel A and D) or B. megaterium (panel B) and...
Figure 3: Growth kinetics of B. megaterium under the influence of different amounts of synAMP (red: (RW)3; or...
Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41
- Evan F. Haney,
- Leonard T. Nguyen,
- David J. Schibli and
- Hans J. Vogel
Beilstein J. Org. Chem. 2012, 8, 1172–1184, doi:10.3762/bjoc.8.130
- with enhanced antimicrobial potency and weak cytotoxic activity. The first step in this process was to select an appropriate sequence to serve as the peptide scaffold. Many linear AMPs are unstructured in aqueous solution and only adopt a well-defined structure in the presence of a lipid bilayer [1
- ]. This binding event is integral to the mechanism of action of the peptide, either through direct damage to the phospholipid bilayer or by allowing the peptide to cross the bacterial membrane to reach intracellular targets [2]. A number of AMPs form amphipathic α-helices when bound to lipid bilayers with
- solutions caused substantial blue shifts of the maximum wavelength in the Trp emission spectra (Figure 2B). The maximum wavelength of the gp41w-4R samples blue shifted in all the lipid environments, with the largest changes occurring in the presence of anionic LUVs and detergents. Gp41w-KA also displayed
Graphical Abstract
Figure 1: (A) Names and sequences of the gp41w-derived peptides. (B) Helical-wheel projections of gp41w, gp41...
Figure 2: (A) Normalized Trp emission spectra of the gp41w derivatives in buffer. The spectra have been norma...
Figure 3: Relative Ksv values calculated for gp41w, gp41w-4R, gp41w-KA and gp41w-FKA in buffer and in the pre...
Figure 4: Percent calcein leakage induced by the gp41 derivatives. Gp41w (blue), gp41w-4R (orange), gp41w-KA ...
Figure 5: DSC thermograms of pure zwitterionic DPPC (left) and anionic DPPG (right) lipid suspensions compare...
Figure 6: Far-UV CD spectra of gp41w and the three derivative peptides. The panel on the left shows the pepti...
Figure 7: NMR solution structure of gp41w-4R, gp41w-KA and gp41w-FKA in the cosolvent mixture. Overlay of the...
Partial thioamide scan on the lipopeptaibiotic trichogin GA IV. Effects on folding and bioactivity
- Marta De Zotti,
- Barbara Biondi,
- Cristina Peggion,
- Matteo De Poli,
- Haleh Fathi,
- Simona Oancea,
- Claudio Toniolo and
- Fernando Formaggio
Beilstein J. Org. Chem. 2012, 8, 1161–1171, doi:10.3762/bjoc.8.129
- SUVs was performed in a similar way as described in reference [59]. Leakage from lipid vesicles The peptide-induced leakage from SUVs was measured at 293 K by using the CF-entrapped vesicle technique [65] and a Perkin Elmer model MPF-66 spectrofluorimeter. SUVs were prepared as described above. The
- phospholipid concentration was kept constant (0.06 mM), and increasing [peptide]/[lipid] molar ratios (R−1) were obtained by adding aliquots of each non-hydrosoluble, monothionated peptide (or of trichogin GA IV, used as reference compound) as a MeOH solution, keeping the final MeOH concentration below 5% by
Graphical Abstract
Figure 1: List of primary structures and abbreviations for the peptides studied in this work. The [Leu11-OMe]...
Scheme 1: Synthesis of ψ[CS-NH]2. 1: Coupling in the presence of EDC/HOBt. 2: Deprotection by using TFA/DCM. ...
Scheme 2: Synthesis of ψ[CS-NH]5. 1: Coupling in the presence of EDC/HOBt. 2: Deprotection by using TFA/DCM. ...
Scheme 3: Synthesis of ψ[CS-NH]9. 1: Deprotection by catalytic hydrogenation with Pd/C. 2: Coupling with n-Oc...
Figure 2: RP-HPLC profiles obtained for [Leu11-OMe] trichogin GA IV (tric-OMe) and its ψ[CS-NH]2, ψ[CS-NH]5, ...
Figure 3: Far-UV (panel I) and near-UV (panel II) CD spectra of [Leu11-OMe] trichogin GA IV (tric-OMe) and it...
Figure 4: FT-IR absorption spectra (3550–3200 cm−1 region) in CDCl3 solution of [Leu11-OMe] trichogin GA IV (...
Figure 5: Region of the amide NH protons in the H/H-ROESY spectrum of ψ[CS-NH]9 (400 MHz, 1 mM in CD3CN solut...
Figure 6: Fingerprint region of the H/H-ROESY spectrum of ψ[CS-NH]9 (400 MHz, 1 mM in CD3CN solution, 298 K)....
Figure 7: Fingerprint region of the H/H-ROESY spectrum of ψ[CS-NH]9 (400 MHz, 1 mM in CD3CN solution, 298 K)....
Figure 8: Ribbon representation of the lowest energy (138.7 kcal/mol) 3D structure obtained for ψ[CS-NH]9. Al...
Triterpenoid saponins from the roots of Acanthophyllum gypsophiloides Regel
- Elena A. Khatuntseva,
- Vladimir M. Men’shov,
- Alexander S. Shashkov,
- Yury E. Tsvetkov,
- Rodion N. Stepanenko,
- Raymonda Ya. Vlasenko,
- Elvira E. Shults,
- Genrikh A. Tolstikov,
- Tatjana G. Tolstikova,
- Dimitri S. Baev,
- Vasiliy A. Kaledin,
- Nelli A. Popova,
- Valeriy P. Nikolin,
- Pavel P. Laktionov,
- Anna V. Cherepanova,
- Tatiana V. Kulakovskaya,
- Ekaterina V. Kulakovskaya and
- Nikolay E. Nifantiev
Beilstein J. Org. Chem. 2012, 8, 763–775, doi:10.3762/bjoc.8.87
- nature of compounds 1 and 2, the presence of glucuronic acid at C-3 of the aglycone, and the absence of a lipid moiety. Histamine-induced acute inflammation in the paws of the mice was used as a classical model of edema formation for the study of the anti-inflammatory activity of saponins. Two methods of
Graphical Abstract
Figure 1: Saponins from A. gypsophiloides 1, R = OH and 2, R = H.
Figure 2: Part of a 2D ROESY spectrum of compound 1. The corresponding parts of the 1H NMR spectrum are shown...
Figure 3: Key ROESY (dashed line) correlations for compound 1.
Figure 4: Part of the HMBC spectrum of compound 1. 1H and 13C NMR spectra are shown along the horizontal and ...
Figure 5: IL-6 production of primary endotheliocytes in the presence of compounds 1 and 2. Error bars represe...
Figure 6: Growth inhibition zones for F. neoformans IGC 3957 in the presence of compounds 1 and 2 at pH 4.0. ...
An easy α-glycosylation methodology for the synthesis and stereochemistry of mycoplasma α-glycolipid antigens
- Yoshihiro Nishida,
- Yuko Shingu,
- Yuan Mengfei,
- Kazuo Fukuda,
- Hirofumi Dohi,
- Sachie Matsuda and
- Kazuhiro Matsuda
Beilstein J. Org. Chem. 2012, 8, 629–639, doi:10.3762/bjoc.8.70
- %) conformers around the lipid tail, while adopting all of the three conformers with equal probability around the sugar position. This property was very close to what we have observed with respect to the conformation of phosphatidylcholine (DPPC), suggesting that the Mycoplasma glycolipids GGPLs may constitute
- symmetric lipid, the asymmetric phospholipid (DPPC) favors the gt-conformer more strongly around the tail lipid moiety along the sn-1,2 position, while disfavoring the tg-conformer, in the ratio of gt (59%), gg (34%) and tg (7%). The head phosphate moiety along the sn-2,3 position adopts the three
- conformers in equilibrated populations (gg = gt = tg). 3-O-(α-D-glucopyranosyl)-sn-glycerolipids 10 and 11 (Figure 3, entries 3 and 4) were found to have conformational properties very similar to DPPC; the lipid tail moiety prefers the gauche conformations (gt and gg), while the sugar moiety allows a random
Graphical Abstract
Figure 1: Absolute chemical structures of M. fermentans α-glycolipid antigens, GGPL-I and GGPl-III (GGPL: Gly...
Scheme 1: An established synthetic pathway to α-glycosyl-sn-glycerols 4a and 5a. A reagent combination of CBr4...
Scheme 2: Syntheses of GGPL-I homologue I-a and its isomer I-b. Conditions: (a) K2CO3, CH3OH; (b) cesium palm...
Figure 2: 1H NMR spectra of I-a and I-b (500 MHz, 25 °C, CDCl3/CD3OD 10:1). The assignment of sn-glycerol met...
Figure 3: Distributions of gg, gt and tg-conformers in 3-substituted sn-glycerols at 11 mM in solutions of CD...
Figure 4: Distributions of gg, gt and tg-conformers in 1-substituted sn-glycerols. In these sn-isomers, Φ1 an...
Figure 5: A common conformational property of GGPL-I and DPPC. The tail lipid moiety favors two gauche-confor...
Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation
- Toshiki Nokami,
- Akito Shibuya,
- Yoshihiro Saigusa,
- Shino Manabe,
- Yukishige Ito and
- Jun-ichi Yoshida
Beilstein J. Org. Chem. 2012, 8, 456–460, doi:10.3762/bjoc.8.52
- Stereoselective formation of glycosidic linkages is the key issue in oligosaccharide synthesis, because both 1,2-trans and 1,2-cis aminoglycosides are ubiquitous in biologically active oligosaccharides [1][2][3][4][5]. The 1,2-trans aminoglycosides, which are found in Nod factor [1] and lipid A [2], can be easily
Graphical Abstract
Scheme 1: Electrochemical conversion of thioglycosides to glycosyl triflates.
Figure 1: 1H NMR spectrum of glycosyl triflate 2a.
Scheme 2: Triflic acid mediated isomerization of β-glycoside.
Planar-bilayer activities of linear oligoester bolaamphiphiles
- Jonathan K. W. Chui,
- Thomas M. Fyles and
- Horace Luong
Beilstein J. Org. Chem. 2011, 7, 1562–1569, doi:10.3762/bjoc.7.184
- between different linear bolaamphiphiles and correspond to the influence of each unique architecture on the overall system behavior. This is experimental support for the proposal [10] that there is some underlying energetic landscape that is as much a property of the system (lipid, water, and compound) as
- underlying mechanism? One line of possibilities relates to the underlying “system property” mentioned earlier. It is known that pure lipids near their phase transitions can show single-channel conductance activities; while the specific mode of action depends on the identity of the lipid, discrete conductance
- events indistinguishable from channels are possible [26]. It was recently reported that an applied potential can effect lipid phase transitions [27], one consequence of which is the creation of voltage-dependent lipid ion channels at the phase-transition temperature. Pure diphytanoyl phosphatidylcholine
Graphical Abstract
Scheme 1: Compounds studied with the voltage-clamp experiment.
Scheme 2: Synthesis of phthalate compounds.
Figure 1: Channel activities of compound 1. A: Regular “square-top” activity. Conditions: 1 M KCl buffered to...
Figure 2: Channel activities of compound 2. A: Rapid flickering. Conditions: 1 M CsCl, +100 mV; B: Semiregula...
Figure 3: Conversion of a current–time profile of compound 5 (top) into conductance–time profile (bottom) by ...
Figure 4: Single-molecule structure–activity relationships for compounds 1–8. Grids are given in the followin...
Figure 5: Voltage-dependent opening of compound 1. Inset: Exponential dependence of the mean current on the p...
Advances in synthetic approach to and antifungal activity of triazoles
- Kumari Shalini,
- Nitin Kumar,
- Sushma Drabu and
- Pramod Kumar Sharma
Beilstein J. Org. Chem. 2011, 7, 668–677, doi:10.3762/bjoc.7.79
- antifungal for IFIs was amphotericin B. With the introduction of triazoles at the beginning of 1990s, the pace of drug development accelerated. Amphotericin B (AMB) was incorporated in three lipid formulations, whilst the first-generation triazoles (fluconazole (9) and itraconazole (10)) changed the
Graphical Abstract
Figure 1: Isomeric forms of triazole.
Scheme 1: Copper catalyzed azide–alkyne cycloaddition.
Scheme 2: Ruthenium catalyzed azide–alkyne cycloaddition.
Scheme 3: Copper-sulfate catalyzed azide–alkyne cycloaddition.
Scheme 4: Azide–dimethylbut-2-yne-dioate cycloaddition.
Figure 2: Triazole compound 3 with most potent antifugal activity against various strains [20].
Figure 3: Triazole compounds 4 and 5 showing antifungal activity against Candida albicans [31].
Figure 4: Triazole compound 6 with the highest activity against Aspergillus flavus, Aspergillus versicolor, A...
Figure 5: Triazole compound 7 exhibiting an MIC of 25 µg/mL against Aspergillus niger [33].
Figure 6: Triazole compound 8 showing the most significant activity against Aspergillus niger and Fusarium ox...
Figure 7: Ergosterol biosynthesis inhibitor pathway.
Figure 8: Fluconazole (9).
Figure 9: Itraconazole (10).
Figure 10: Voriconazole (11).
Figure 11: Posaconazole (12).
Figure 12: Ravuconazole (13).
Synthesis and self-assembly of 1-deoxyglucose derivatives as low molecular weight organogelators
- Guijun Wang,
- Hao Yang,
- Sherwin Cheuk and
- Sherman Coleman
Beilstein J. Org. Chem. 2011, 7, 234–242, doi:10.3762/bjoc.7.31
- of UV treatment, it produced a dark blue colored gel (Figure 4e). The blue gel also exhibited interesting color transition properties upon heating (Figure 4f). For a comparison of the two sugar headgroups, the lipid 19 [35] was able gelate ethanol at 7 mg/mL, but it cannot be polymerized as easily
Graphical Abstract
Figure 1: Structures of three ester derivatives of compound 1.
Figure 2: Structures of ester analogs 5–7 and headgroup 8.
Scheme 1: Synthesis of a series of esters 9A–18C.
Figure 3: Optical micrographs of the gels formed by compound 9A in hexane at 15 mg/mL (A, B), 9B in DMSO/wate...
Figure 4: An ethanol gel formed by compound 18A at <10 mg/mL. a) A clear solution when heated above 70 °C; b)...
Figure 5: Optical micrographs under bright field (a, b) and scanning electron micrograph (c) of the gel forme...
Figure 6: The UV–vis absorption spectra of the polymerized gel formed by compound 18A in ethanol (10 mg/mL): ...
Pyridinium based amphiphilic hydrogelators as potential antibacterial agents
- Sayanti Brahmachari,
- Sisir Debnath,
- Sounak Dutta and
- Prasanta Kumar Das
Beilstein J. Org. Chem. 2010, 6, 859–868, doi:10.3762/bjoc.6.101
- the difference in the lipid composition as well as in the membrane potential gradient between the target prokaryotic and the non-target eukaryotic cell membranes [41][42]. Conclusion We have utilized a combination of a quaternary pyridinium unit and hydrophobic long chain to build a scaffold, which
Graphical Abstract
Figure 1: Structure of amphiphiles 1–5.
Scheme 1: Synthetic procedure of the amphiphiles.
Figure 2: Variation of the Tgel with concentration of amphiphiles 1 and 2.
Figure 3: (a, b) FESEM images of the dried gels of 1 and 2, respectively at their MGC. (c, d) Two- and three-...
Figure 4: Luminescence spectra of 2 in water (λex = 330 nm) at various concentrations and room temperature.
Figure 5: FTIR spectra of (a) 1 and (b) 2 in CHCl3 solution (dashed line) and in D2O at the gel state (solid ...
Figure 6: 2D-NOESY spectra of 2 (2%, w/v) in DMSO-d6 with 70% water.
Figure 7: XRD diagram of the dried gel of 2.
Figure 8: Schematic representation of the possible arrangement of molecules during hydrogelation of 2.
Figure 9: MTT assay based percent NIH3T3 cell viability as a function of concentration of amphiphile 2.
Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation
- Vladimir N. Boiko
Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88
- ligands and even by dimethylformamide. One of the driving forces for the synthesis of perfluoroalkyl sulphides is the high lipophilic properties of perfluoroalkylthio groups (the greatest Hansch constant π = 1.44, belongs to SCF3 group [1]), which increases the ability of such molecules to cross lipid
Graphical Abstract
Figure 1: Examples of industrial fluorine-containing bio-active molecules.
Figure 2: CF3(S)- and CF3(O)-containing pharmacologically active compounds.
Figure 3: Hypotensive candidates with SRF and SO2RF groups – analogues of Losartan and Nifedipin.
Figure 4: The variety of the pharmacological activity of RFS-substituted compounds.
Figure 5: Recent examples of compounds containing RFS(O)n-groups [12-18].
Scheme 1: Fluorination of ArSCCl3 to corresponding ArSCF3 derivatives. For references see: a[38-43]; b[41,42]; c[43]; d[44]; e[38-43,45-47]; f[38-43,48,49]; g...
Scheme 2: Preparation of aryl pentafluoroethyl sulfides.
Scheme 3: Mild fluorination of the aryl SCF2Br derivatives.
Scheme 4: HF fluorinations of aryl α,α,β-trichloroisobutyl sulfide at various conditions.
Scheme 5: Monofluorination of α,α-dichloromethylene group.
Scheme 6: Electrophilic substitution of phenols with CF3SCl [69].
Scheme 7: Introduction of SCF3 groups into activated phenols [71-74].
Scheme 8: Preparation of tetrakis(SCF3)-4-methoxyphenol [72].
Scheme 9: The interactions of resorcinol and phloroglucinol derivatives with RFSCl.
Scheme 10: Reactions of anilines with CF3SCl.
Scheme 11: Trifluoromethylsulfanylation of anilines with electron-donating groups in the meta position [74].
Scheme 12: Reaction of benzene with CF3SCl/CF3SO3H [77].
Scheme 13: Reactions of trifluoromethyl sulfenyl chloride with aryl magnesium and -mercury substrates.
Scheme 14: Reactions of pyrroles with CF3SCl.
Scheme 15: Trifluoromethylsulfanylation of indole and indolizines.
Scheme 16: Reactions of N-methylpyrrole with CF3SCl [80,82].
Scheme 17: Reactions of furan, thiophene and selenophene with CF3SCl.
Scheme 18: Trifluoromethylsulfanylation of imidazole and thiazole derivatives [83].
Scheme 19: Trifluoromethylsulfanylation of pyridine requires initial hydride reduction.
Scheme 20: Introduction of additional RFS-groups into heterocyclic compounds in the presence of CF3SO3H.
Scheme 21: Introduction of additional RFS-groups into pyrroles [82,87].
Scheme 22: By-products in reactions of pyrroles with CF3SCl [82].
Scheme 23: Reaction of aromatic iodides with CuSCF3 [93,95].
Scheme 24: Reaction of aromatic iodides with RFZCu (Z = S, Se), RF = CF3, C6F5 [93,95,96].
Scheme 25: Side reactions during trifluoromethylsulfanylation of aromatic iodides with CF3SCu [98].
Scheme 26: Reactions with in situ generated CuSCF3.
Scheme 27: Perfluoroalkylthiolation of aryl iodides with bulky RFSCu [105].
Scheme 28: In situ formation and reaction of RFZCu with aryl iodides.
Figure 6: Examples of compounds obtained using in situ generated RFZCu methodology [94].
Scheme 29: Introduction of SCF3 group into aromatics via difluorocarbene.
Scheme 30: Tetrakis(dimethylamino)ethylene dication trifluoromethyl thiolate as a stable reagent for substitut...
Scheme 31: The use of CF2=S/CsF or (CF3S)2C=S/CsF for the introduction of CF3S groups into fluorinated heteroc...
Scheme 32: One-pot synthesis of ArSCF3 from ArX, CCl2=S and KF.
Scheme 33: Reaction of aromatics with CF3S− Kat+ [115].
Scheme 34: Reactions of activated aromatic chlorides with AgSCF3/KI.
Scheme 35: Comparative CuSCF3/KI and Hg(SCF3)2/KI reactions.
Scheme 36: Me3SnTeCF3 – a reagent for the introduction of the TeCF3 group.
Scheme 37: Sandmeyer reactions with CuSCF3.
Scheme 38: Reactions of perfluoroalkyl iodides with alkali and organolithium reagents.
Scheme 39: Perfluoroalkylation with preliminary breaking of the disulfide bond.
Scheme 40: Preparation of RFS-substituted anilines from dinitrodiphenyl disulfides.
Scheme 41: Photochemical trifluoromethylation of 2,4,6-trimercaptochlorobenzene [163].
Scheme 42: Putative process for the formation of B, C and D.
Scheme 43: Trifluoromethylation of 2-mercapto-4-hydroxy-6-trifluoromethylyrimidine [145].
Scheme 44: Deactivation of 2-mercapto-4-hydroxypyrimidines S-centered radicals.
Scheme 45: Perfluoroalkylation of thiolates with CF3Br under UV irradiation.
Scheme 46: Catalytic effect of methylviologen for RF• generation.
Scheme 47: SO2−• catalyzed trifluoromethylation.
Scheme 48: Electrochemical reduction of CF3Br in the presence of SO2 [199,200].
Scheme 49: Participation of SO2 in the oxidation of ArSCF3−•.
Scheme 50: Electron transfer cascade involving SO2 and MV.
Scheme 51: Four stages of the SRN1 mechanism for thiol perfluoroalkylation.
Scheme 52: A double role of MV in the catalysis of RFI reactions with aryl thiols.
Scheme 53: Photochemical reaction of pentafluoroiodobenzene with trifluoromethyl disulfide.
Scheme 54: N- Trifluoromethyl-N-nitrosobenzene sulfonamide – a source of CF3• radicals [212,213].
Scheme 55: Radical trifluoromethylation of organic disulfides with ArSO2N=NCF3.
Scheme 56: Barton’s S-perfluoroalkylation reactions [216].
Scheme 57: Decarboxylation of thiohydroxamic esters in the presence of C6F13I.
Scheme 58: Reactions of thioesters of trifluoroacetic and trifluoromethanesulfonic acids in the presence of ar...
Scheme 59: Perfluoroalkylation of polychloropyridine thiols with xenon perfluorocarboxylates or XeF2 [222,223].
Scheme 60: Interaction of Xe(OCORF)2 with nitroaryl disulfide [227].
Scheme 61: Bi(CF3)3/Cu(OCOCH3)2 trifluoromethylation of thiophenolate [230].
Scheme 62: Reaction of fluorinated carbanions with aryl sulfenyl chlorides.
Scheme 63: Reaction of methyl perfluoromethacrylate with PhSCl in the presence of fluoride.
Scheme 64: Reactions of ArSCN with potassium and magnesium perfluorocarbanions [237].
Scheme 65: Reactions of RFI with TDAE and organic disulfides [239,240].
Scheme 66: Decarboxylation of perfluorocarboxylates in the presence of disulfides [245].
Scheme 67: Organization of a stable form of “CF3−” anion in the DMF.
Scheme 68: Silylated amines in the presence of fluoride can deprotonate fluoroform for reaction with disulfide...
Figure 7: Other examples of aminomethanols [264].
Scheme 69: Trifluoromethylation of diphenyl disulfide with PhSO2CF3/t-BuOK.
Scheme 70: Amides of trifluoromethane sulfinic acid are sources of CF3− anion.
Scheme 71: Trifluoromethylation of various thiols using “hyper-valent” iodine (III) reagent [279].
Scheme 72: Trifluoromethylation of p-nitrothiophenolate with diaryl CF3 sulfonium salts [280].
Scheme 73: Trifluoromethyl transfer from dibenzo (CF3)S-, (CF3)Se- and (CF3)Te-phenium salts to thiolates [283].
Scheme 74: Multi-stage paths for synthesis of dibenzo-CF3-thiophenium salts [61].
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...
The development and evaluation of a continuous flow process for the lipase- mediated oxidation of alkenes
- Charlotte Wiles,
- Marcus J. Hammond and
- Paul Watts
Beilstein J. Org. Chem. 2009, 5, No. 27, doi:10.3762/bjoc.5.27
- such as H2O2 (2) and urea–hydrogen peroxide (UHP, 3) [12]. For this transformation, the biocatalysts of choice are lipases (E.C. 3.1.1.3), which are a group of water soluble enzymes that catalyse the hydrolysis of lipid substrates, i.e. triglycerides and fats, in biological systems and are a subclass
Graphical Abstract
Scheme 1: Illustration of the chemo-enzymatic epoxidation of an alkene; involving the biocatalytic perhydroly...
Scheme 2: Illustration of the chemo-enzymatic epoxidation of 1-methylcyclohexene (6) to 1-methylcyclohexene o...
Scheme 3: Model reaction used to compare the continuous flow epoxidation strategy with the conventional batch...
Figure 1: Schematic of the reaction set-up used to evaluate the continuous flow chemo-enzymatic epoxidation o...
Figure 2: Graph illustrating the effect of flow rate (hence residence time) on the conversion of 1-methylcycl...
Figure 3: Graph illustrating the effect of (a) flow rate and (b) residence time on the conversion of 1-methyl...
Figure 4: Graph illustrating the effect of oxidant stoichiometry on the conversion of 1-methylcyclohexene (6)...
Figure 5: Illustration of the enzyme 4 stability to H2O2 (2) for the conversion of 1-methylcyclohexene (6) to...
Scheme 4: Illustration of the reaction products obtained when conducting the continuous flow epoxidation of c...
Trifluoromethyl ethers – synthesis and properties of an unusual substituent
- Frédéric R. Leroux,
- Baptiste Manteau,
- Jean-Pierre Vors and
- Sergiy Pazenok
Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13
- advantageously a fluorine atom (π = +0.14) in most molecules with the benefit of increased lipid solubility. Acidity of trifluoromethyl ethers As described previously, the trifluoromethoxy group is at the same time a strong electron-withdrawing substituent due to the three fluorine atoms and a π-donating
Graphical Abstract
Figure 1: OCF3-bearing pesticides.
Scheme 1: Preparation of trifluoromethyl ethers via a chlorination/fluorination sequence.
Scheme 2: Preparation of trifluoromethyl ethers via an in situ chlorination/fluorination sequence.
Scheme 3: Preparation of trifluoromethyl ethers via chlorothionoformates.
Scheme 4: Preparation of trifluoromethyl ethers via fluoroformates.
Scheme 5: Oxidative desulfurization-fluorination toward trifluoromethyl ethers.
Scheme 6: Mechanism of the oxidative desulfurization-fluorination.
Scheme 7: Umemoto's O-(trifluoromethyl)dibenzofuranium salts 4 as CF3-transfer agents.
Scheme 8: Togni's approach using hypervalent iodine compounds as CF3-transfer agents.
Scheme 9: TAS OCF3 as a nucleophilic OCF3-transfer agent.
Figure 2: Mesomeric structures of the OCF3-group.
Figure 3: Structures of 6 and 7.
Figure 4: Conformational preference of the trifluoromethoxy group on aryl rings.
Scheme 10: Nitration of trifluoromethoxy benzene.
Scheme 11: Synthesis and Nitration of N-Acetyl-(trifluoromethoxy)anilines.
Scheme 12: Bromine/lithium exchange of bromo(trifluoromethoxy)benzenes.
Scheme 13: Metalation of (trifluoromethoxy)benzene.
Scheme 14: Metalation of (trifluoromethoxy)naphthalenes.
Scheme 15: Competition between -CF3- and -OCF3 in Metalation reactions.
Scheme 16: Competition between -F- and -OCF3 in Metalation reactions.
Scheme 17: Metalation of trifluoromethoxyanisoles.
Figure 5: Direction of π-polarization depending on the substituent as described by Schlosser et al. [57].
Scheme 18: Metalation of Bromo(trifluoromethoxy)benzenes.
Scheme 19: Aryne formation from bromo(trifluoromethoxy)phenyllithiums and subsequent Diels-Alder cycloaddition...
Scheme 20: Metalation of (trifluoromethoxy)anilines.
Stereoselective synthesis of (2S,3S,4Z)-4-fluoro- 1,3-dihydroxy- 2-(octadecanoylamino)octadec- 4-ene, [(Z)-4-fluoroceramide], and its phase behavior at the air/water interface
- Gergana S. Nikolova and
- Günter Haufe
Beilstein J. Org. Chem. 2008, 4, No. 12, doi:10.3762/bjoc.4.12
- , sphingolipids are crucial e.g. for the function of the skin because they contribute to the formation of the water permeability barrier consisting of a highly organized multilaminar lipid matrix of free fatty acids, cholesterol and ceramides containing additional hydroxyl groups in the sphingosin part and longer
- water permeability barrier consisting of a highly organized multilaminar lipid matrix of free fatty acids, cholesterol and ceramides containing additional hydroxyl groups in the sphingosin part and longer fatty acid amide functions [23]. The function of the additional free OH group seems to be the
- formation of additional hydrogen bridges, which enhance the rigidity of the intercellular lipid aggregates and hence decrease the transepidermal water loss [24][25]. Several of the biological properties of sphingosines and ceramides (e.g. sphingomyelinase activity) were assigned to the OH group in the 3
Graphical Abstract
Figure 1: Natural sphingosines 1a, 2a and synthesized fluorinated analogues 1b, 2b.
Scheme 1: Synthesis of 4-fluorosphingosine (2b); Reagents: i ClTi(OEt)3/Et3N, CH2Cl2, 13 h, 0 °C; ii 15% aq c...
Scheme 2: Mechanism of the aldol reaction.
Figure 2: Favorable conformations of the tert-butyl amino acid ester 7.
Figure 3: π–A Isotherms of ceramide (2a) and 4-fluoroceramide (2b) at 20 °C (80 cm2/min compression velocity)....
Figure 4: Cycles of compression and expansion for ceramide (2a) and 4-fluoroceramide (2b).
ADDP and PS-PPh3: an efficient Mitsunobu protocol for the preparation of pyridine ether PPAR agonists
- Paul S. Humphries,
- Quyen-Quyen T. Do and
- David M. Wilhite
Beilstein J. Org. Chem. 2006, 2, No. 21, doi:10.1186/1860-5397-2-21
- pathways for lipid handling, insulin sensitivity, inflammation and other functions have led to marketed drugs and vast clinical and preclinical research efforts.[1][2][3][4][5][6][7][8][9][10][11] In 1991, a series of PPAR analogues were disclosed, which for the first time did not contain a thiazolidine
Graphical Abstract
Figure 1: Thiazolidine-2,4-dione mimic & chosen lead scaffold.
Scheme 1: Reagents and conditions: (a) PS-PPh3, DEAD, THF, rt, 16 h, 54%.
Figure 2: Proposed mechanism of the Mitsunobu reaction.
Scheme 2: Reagents and conditions: (a) PS-PPh3, ADDP, THF, rt, 16 h, 81%.
Scheme 3: Reagents and conditions: (a) 1 N aq. NaOH, MeCN, 100°C μW, 10 mins, 96%.
