Search results
Search for "mimicry" in Full Text gives 17 result(s) in Beilstein Journal of Organic Chemistry.
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
- process at photosystem II (PSII) via an electron transfer chain to photosystem I (PSI) where a second photoexcitation occurs [13][14]. Mimicry of this “Z-scheme” led to a seminal disclosure the concept of consecutive photoinduced electron transfer (conPET) by König and co-workers in 2014 for the
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.
Synthesis and bioactivity of pyrrole-conjugated phosphopeptides
- Qiuxin Zhang,
- Weiyi Tan and
- Bing Xu
Beilstein J. Org. Chem. 2022, 18, 159–166, doi:10.3762/bjoc.18.17
- ][11], collagen mimic [12], antibacterial [13][14], biomineralization [15][16], mimicry of amyloids [17], cell cultures [18], and tissue engineering [19]. Particularly, the use of enzyme-instructed self-assembly (EISA) [20][21] of peptide assemblies has expanded the applications of peptide assemblies
Graphical Abstract
Scheme 1: Molecular structures of the parent phosphopeptide 1 and its pyrrole-conjugated analogs 2–14.
Figure 1: Cell viability of HeLa cells treated with 200 μM of each compound for 24 h.
Figure 2: Cell viability of HeLa cells treated with 20 μM, 50 μM, 100 μM, 200 μM and 400 μM of 1, 4a and 6b f...
Figure 3: A) TEM images of 1 before and after addition of ALP (0.5 U/mL) in PBS buffer (pH 7.4). Scale bar is...
3-Acetoxy-fatty acid isoprenyl esters from androconia of the ithomiine butterfly Ithomia salapia
- Florian Mann,
- Daiane Szczerbowski,
- Lisa de Silva,
- Melanie McClure,
- Marianne Elias and
- Stefan Schulz
Beilstein J. Org. Chem. 2020, 16, 2776–2787, doi:10.3762/bjoc.16.228
- spectrometry; mimicry; pheromones; pyrrolizidine alkaloids; Introduction The Neotropical butterfly tribe Ithomiini (Nymphalidae: Danainae) is very diverse and species-rich, with over 390 species and 50 genera [1][2] and extensively involved in Müllerian mimetic interactions [3]. Ithomiines are well suited for
Graphical Abstract
Figure 1: Extended hairs (arrow) of the androconia of a male Ithomia salapia aquinia (Photo: Melanie McClure)....
Scheme 1: Pyrrolizidine alkaloid lycopsamine (1) and the putative pheromone compounds methyl hydroxydanaidoat...
Scheme 2: Biosynthetic formation of hedycaryol (7) and α-elemol (8).
Figure 2: Total ion current chromatogram of androconial extracts of male butterflies of the two subspecies I....
Figure 3: Proposed mass spectrometric formation of characteristic ions in prenyl and isoprenyl esters. Format...
Figure 4: Mass spectra and fragmentation of A: isoprenyl (3-methyl-3-butenyl) 9-octadenoate (9) and B: prenyl...
Figure 5: Mass spectra and fragmentation of A: isoprenyl 3-acetoxyoctadecanoate (11); B: isoprenyl (Z)-3-acet...
Scheme 3: Synthesis of isoprenyl 3-acetoxyoctadecanoate (11). a) IBX, EtOAc, 60 °C, 3.15 h, 99%; b) SnCl2, CH2...
Scheme 4: a) 48% HBraq, toluene, 24 h, 110 °C, 79%; b) IBX, EtOAc, 60 °C, 3.15 h, 90%; c) C5H11PPh3Br, LDA, T...
Figure 6: Separation of the enantiomers of methyl (Z)-3-hydroxy-13-octadecenoate (25) on a β-6-TBDMS hydrodex...
Scheme 5: Proposed biosynthetic pathway of fatty acids leading to the observed regioisomers of the isoprenyl ...
Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides
- Dongsik Yang,
- Hongjian He and
- Bing Xu
Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221
- ][20][21][22][23][24][25][26], as mimicry of amyloids [27], in the context of intracellular phase transition [28], and in molecular imaging [29][30]. Most of these studies are centered on peptide amphiphiles or amphiphilic peptides that are linear in geometry. Nature, however, also produces and
Graphical Abstract
Figure 1: A) The molecular structures of the branched peptides Nap-ffk(NH2-DEDDDLLIG)y (1) and Nap-ffk(AcNH-D...
Scheme 1: Synthetic route to the branched peptides. (i) HBTU, DIPEA, DMF, 12 h, rt, (ii) TFA, 2 h, rt, and (i...
Figure 2: A) LC–MS spectrum of the proteolytic products after 1 (5 mM) was incubated with proteinase K (5 U/m...
Figure 3: Optical images of solutions of 1 and 2 (5 mM), respectively, with or without proteinase K (5 U/mL) ...
Figure 4: TEM images of the branched peptides before and after the addition of proteinase K into the solution...
Figure 5: Cell viability of HeLa and Saos-2 cells treated with 1 (A) and 2 (B).
Figure 6: Confocal images of HeLa cells treated with a mixture of RPE (8 μg/mL) and A) 1 (400 μM) or B) 2 (40...
Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity
- Yuvixza Lizarme-Salas,
- Alexandra Daryl Ariawan,
- Ranjala Ratnayake,
- Hendrik Luesch,
- Angela Finch and
- Luke Hunter
Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216
- for this work; the crystal structure is shown [14]. In this work, a hypothetical analog 2 was designed to mimic parent compound 1. The predicted low-energy rotamers of 2 about the F–C–C–F and F–C–C=O bonds are shown; rotamers I and IV give the best mimicry of 1. Conformational analysis of 2 by DFT and
Graphical Abstract
Figure 1: The natural product piperine (1) is the inspiration for this work; the crystal structure is shown [14]....
Scheme 1: The attempted synthesis of 6 (a diastereoisomer of 2) via a one-step 1,2-difluorination reaction [24]. ...
Scheme 2: The attempted synthesis of 2 via a stepwise fluorination approach (ether series). THF = tetrahydrof...
Scheme 3: Synthesis of compound 2 via a stepwise fluorination approach (ester series). DIC = diisopropylcarbo...
Figure 2: Conformational analysis of 2 by DFT and NMR. The numbering scheme for NMR spins is given on structu...
Figure 3: Analog 2 has greater stability to UV light than does piperine (1).
Figure 4: Biological activity of piperine (1) and derivative 2. (a) Inihbition of AChE by 1 (IC50 >1000 μM) a...
Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering
- Eric J. N. Helfrich,
- Geng-Min Lin,
- Christopher A. Voigt and
- Jon Clardy
Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283
- functionalization of nonactivated carbon atoms is one of the remaining challenges in organic synthesis [100][112][113]. Despite the progress made in total synthesis of terpenoids and the introduction of the two-phase mimicry of terpene biosynthesis during biomimetic syntheses, it has become obvious that total
Graphical Abstract
Figure 1: Examples of bioactive terpenoids.
Figure 2: Repetitive electrophilic and nucleophilic functionalities in terpene and type II PKS-derived polyke...
Figure 3: Abundance and distribution of bacterial terpene biosynthetic gene clusters as determined by genome ...
Figure 4: Terpenoid biosynthesis. Terpenoid biosynthesis is divided into two phases, 1) terpene scaffold gene...
Figure 5: Mechanisms for type I, type II, and type II/type I tandem terpene cyclases. a) Tail-to-head class I...
Figure 6: Functional TC characterization. a) Different terpenes were produced when hedycaryol (18) synthase a...
Figure 7: Selected examples of terpene modification by bacterial CYPs. a) Hydroxylation [89]. b) Carboxylation, h...
Figure 8: Off-target effects observed during heterologous expression of terpenoid BGCs. Unexpected oxidation ...
Figure 9: TC promiscuity and engineering. a) Spata-13,17-diene (39) synthase (SpS) can take C15 and C25 oligo...
Figure 10: Substrate promiscuity and engineering of CYPs. a) Selected examples from using a CYP library to oxi...
Figure 11: Engineering of terpenoid pathways. a) Metabolic network of terpenoid biosynthesis. Toxic intermedia...
Secondary metabolome and its defensive role in the aeolidoidean Phyllodesmium longicirrum, (Gastropoda, Heterobranchia, Nudibranchia)
- Alexander Bogdanov,
- Cora Hertzer,
- Stefan Kehraus,
- Samuel Nietzer,
- Sven Rohde,
- Peter J. Schupp,
- Heike Wägele and
- Gabriele M. König
Beilstein J. Org. Chem. 2017, 13, 502–519, doi:10.3762/bjoc.13.50
- protection, alternative defensive strategies, such as the production of calcareous needles or acidic sulfates, and sequestration or de novo synthesis of toxic metabolites emerged within the opisthobranch taxa [2][3][4][5]. Adaptations and mimicry, which help to hide in habitats is frequent in marine
Graphical Abstract
Figure 1: Secondary metabolites isolated in this study from P. longicirrum.
Figure 2: Structures of secondary metabolites from P. longicirrum as described by Coll et al. in 1985 [13].
Figure 3: Significant 1H,1H COSY correlations as found in compound 1.
Figure 4: Secosterols [22,24] related to 3β,5α,6β-trihydroxy-9-oxo-9,11-secogorgostan-11-ol (1) from P. longicirrum.
Figure 5: Conformational structure of 1 (key NOESY correlations are indicated with blue arrows; coupling cons...
Figure 6: Structure of cembranoid 5. 1H,1H spin systems (A, B and C) are indicated in bold, arrows show key H...
Figure 7: Compound 5 and the most closely related cembranoids from soft corals.
Figure 8: Proposed configuration and selected NOE correlations of bisepoxide 12 (key NOE correlations are ind...
Figure 9: Structures of bisglaucumlids A–C (23–25).
Figure 10: Proposed configuration of the eastern part (rings B, C and D) of isobisglaucumlides B and C (14 and ...
Figure 11: Effect of Phyllodesmium metabolites in different concentrations on predation by Canthigaster soland...
Figure 12: Phylogenetic tree of octocorals relevant as putative food sources for Phyllodesmium spp. Phylogram ...
Assembly of synthetic Aβ miniamyloids on polyol templates
- Sebastian Nils Fischer and
- Armin Geyer
Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284
- minor signal sets in the proton 1H NMR spectra. Detailed analytical studies of 17 and its possible functional mimicry of toxic Aβ amyloids, according to our previous study of irreversibly covalently linked miniamyloids, are under progress. Conclusion In conclusion, we presented a strategy which merges
Graphical Abstract
Figure 1: a) Schematic representation of the Aβ fibril formation. The monomeric peptide is shown as a colored...
Figure 2: a) Peptide boronic acids 1 and 2 are schematically shown as green sticks (peptide) with a red gripp...
Figure 3: Meso-erythritol is a promiscuous polyol which forms mixtures of esters due to the formation of 5-me...
Figure 4: Diol 5 (6.08 mg, 20.0 μmol, 1.0 equiv) and 3-(acetylamino)phenylboronic acid (6, 3.56 mg, 20.0 μmol...
Figure 5: Fmoc-Hot=Tap-OH (8).
Figure 6: Template 9 and boronic acid 6 can form the monoesters 10 and 11, or the diester 12. The signal assi...
Figure 7: Template 9 (2.30 mg, 4.40 µmol, 1.0 equiv) and peptide boronic acid 1 (7.35 mg, 8.80 µmol, 2.0 equi...
Figure 8: Template 5 (1H NMR expansion shown for reference DMSO-d6, 300 K) and peptide Leu-Val-Phe-Phe-Ala ar...
Figure 9: The trimeric template 16 together with 3 equivalents of pentapeptide LVFFA and 2-formylphenylboroni...
Multivalent dendritic polyglycerolamine with arginine and histidine end groups for efficient siRNA transfection
- Fatemeh Sheikhi Mehrabadi,
- Hanxiang Zeng,
- Mark Johnson,
- Cathleen Schlesener,
- Zhibin Guan and
- Rainer Haag
Beilstein J. Org. Chem. 2015, 11, 763–772, doi:10.3762/bjoc.11.86
- efficiency data suggest that the higher transfection efficiency of histidine-functionalized vectors is presumably due to their improved endosomal release. Conclusion We successfully post-modified dPG-NH2 with variable ratios of Arg and His as mimicry of natural histones to afford safe and efficient siRNA
Graphical Abstract
Scheme 1: Synthesis of multivalent arginine and histidine functionalized dPG-NH2 50%. The depicted dPG-NH2 re...
Figure 1: Agarose gel electrophoresis retardation assay of AAdPGs/siRNA polyplexes. (A) dPG-13Arg13His, (B) d...
Figure 2: Size measurements of dPG-NH2 50% and AAdPGs/siRNA complexes. Intensity distributions of all polyple...
Figure 3: The result of MTT assay on a NIH 3T3 cell line transfected with AAdPG, dPG-NH2 50%, and 90%/siRNA p...
Figure 4: Cell viability versus transfection efficiency of dPG-8Arg30His and dPG-NH2 90% at N/P ratio 30.
Figure 5: Summary of transfection results versus viability of AAdPGs with various Arg and His composition rat...
Figure 6: Confocal images of NIH 3T3 cells treated with Cy3-siRNA/vector complexes: (A) naked siRNA, (B) lipo...
Regio- and stereoselective synthesis of new diaminocyclopentanols
- Evgeni A. Larin,
- Valeri S. Kochubei and
- Yuri M. Atroshchenko
Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262
- : diaminocyclopentanols; epoxides; regioselectivity; ring opening; stereoselectivity; Introduction In recent years mimicry of aminoglycosides [1][2][3][4][5][6][7] and nucleosides [8][9][10] has become an important field in pharmaceutical research. Regio- and stereochemical diversities within a sugar-like moiety in
Graphical Abstract
Scheme 1: Preparation of the starting materials.
Figure 1: Amine-based nucleophiles used in the epoxide ring opening reaction.
Scheme 2: Postulated mechanism for the formation of 14a,b.
The diketopiperazine-fused tetrahydro-β-carboline scaffold as a model peptidomimetic with an unusual α-turn secondary structure
- Francesco Airaghi,
- Andrea Fiorati,
- Giordano Lesma,
- Manuele Musolino,
- Alessandro Sacchetti and
- Alessandra Silvani
Beilstein J. Org. Chem. 2013, 9, 147–154, doi:10.3762/bjoc.9.17
- correct geometry for mimicry. Following these studies, the desired isomer 1a of the THBC-DKP based peptidomimetic was synthesized. 1H NMR conformational studies confirmed the presence of the intramolecular thirteen-membered hydrogen bond that characterizes the α-turn conformation, even if a situation of
Graphical Abstract
Figure 1: THBC-DKP-based natural and synthetically made compounds.
Figure 2: THBC-DKP-based peptidomimetic 1a.
Figure 3: Geometric parameters for mimics 1a,b.
Figure 4: Perspective view of the low-energy conformers of 1a,b. Hydrogen atoms are omitted for clarity.
Scheme 1: Synthesis of the THBC-DKP-based peptidomimetic 1a.
Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach
- Pankaj Chauhan and
- Swapandeep Singh Chimni
Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240
- . Organocatalyts also provide an insight into biological catalytic processes, as a number of these catalysts work by the phenomenon of enzyme mimicry. These advantages of chiral organocatalysts also meet many of the requirements of green chemistry [27]. Recently developed, organocatalytic asymmetric
Graphical Abstract
Scheme 1: Proline-catalysed aldol reaction in a ball-mill.
Scheme 2: Proline-catalysed aldol reaction between solid substrates (1b and 2a).
Scheme 3: (S)-Binam-L-prolinamide catalysed asymmetric aldol reaction by using a ball-mill. aConversion.
Scheme 4: Asymmetric aldol reaction assisted by ball-milling catalysed by dipeptides (A) with III and (B) wit...
Scheme 5: Thiodipeptide-catalysed asymmetric aldol reaction of (A) ketones with aldehydes and (B) acetone wit...
Scheme 6: Enantioselective Michael reaction of aldehydes with nitroalkenes catalysed by pyrrolidine-derived o...
Scheme 7: Chiral squaramide catalysed asymmetric Michael reaction assisted by ball-milling.
Scheme 8: Asymmetric organocatalytic Michael reaction assisted by pestle and mortar grinding.
Scheme 9: C-2 symmetric thiourea catalysed enantioselective MBH reaction.
Scheme 10: Quinine-catalysed ring opening of meso-anhydride by ball-milling.
Scheme 11: Ball-milling-assisted (A) synthesis of glycine schiff bases and (B) their organocatalytic asymmetri...
Scheme 12: Enantioselective amination of β-ketoester by using pestle and mortar.
Peptides presenting the binding site of human CD4 for the HIV-1 envelope glycoprotein gp120
- Julia Meier,
- Kristin Kassler,
- Heinrich Sticht and
- Jutta Eichler
Beilstein J. Org. Chem. 2012, 8, 1858–1866, doi:10.3762/bjoc.8.214
- presents the CDR2-like loop of CD4, is able to enhance binding of gp120 to the CD4i antibody mAb X5 [24] (Figure 4), providing further indication of a functional mimicry of CD4 by the mimetic peptides. Comformational stability of gp120-peptide complexes To investigate the conformational stability and
Graphical Abstract
Figure 1: Structural details of the CD4–gp120 complex (pdb 1rzj). The binding site of CD4 for gp120 is shown ...
Figure 2: HPLC chromatograms and ion masses from the ESI-mass spectra (insets) of purified CD4-M2 (M = 5979.8...
Figure 3: Left: Relative affinities (Ar, CD4-M1 = 1) to gp120(IIIB) of peptides. Right: Concentration-depende...
Figure 4: Enhancement of binding of gp120(MN) to the CD4i antibody X5 by CD4-M5 and sCD4, respectively. See E...
Figure 5: Conformational stability of CD4 mimetic peptides in complex with gp120 during 20 ns of MD simulatio...
Figure 6: Structural presentation of peptide motions in the gp120-bound state during the MD simulation. (A) C...
Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays
- Ian Cumpstey,
- Jens Frigell,
- Elias Pershagen,
- Tashfeen Akhtar,
- Elena Moreno-Clavijo,
- Inmaculada Robina,
- Dominic S. Alonzi and
- Terry D. Butters
Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128
- disaccharide mimicry. Last year, we reported that neutral ether- and thioether-linked diglycose derivatives can interact with lectins with affinities similar to those of strongly binding disaccharide ligands [4]. In the related carbasugar series, Ogawa et al. have shown that pseudodisaccharides with a bridging
Graphical Abstract
Scheme 1: The concept of using allylic reactivity enhancement to facilitate diglycoside synthesis.
Scheme 2: (i) Phosphomolybdic acid, EtOH, MeCN, 0 °C→RT, 63%; (ii) a) NaOMe, MeOH, 87%; b) TBDMSCl, imidazole...
Scheme 3: (i) DIAD, PPh3, THF, 0 °C→RT; 10, 91%; 11, 88%; 12, 76%; 13, 91%; 14, 91%; 15, 71%.
Scheme 4: (i) K2OsO4, NMO, acetone, H2O; 16, 88%; 17, 73%; (ii) Ac2O, py, 83%; (iii) MeOH, HCl (1 M aq.); 19,...
Scheme 5: (i) Cl3CCN, DBU, CH2Cl2, 99%; (ii) TMPP, Pd(dba)2, 5, Et3N, MeCN, 24, 44%; 25, 15%; 26, 5%; 27, 6%.
Figure 1: Previously synthesised amine-linked diglycosides.
Synthesis of 6-PEtN-α-D-GalpNAc-(1–>6)-β-D-Galp-(1–>4)-β-D-GlcpNAc-(1–>3)-β-D-Galp-(1–>4)-β-D-Glcp, a Haemophilus influenzae lipopolysacharide structure, and biotin and protein conjugates thereof
- Andreas Sundgren,
- Martina Lahmann and
- Stefan Oscarson
Beilstein J. Org. Chem. 2010, 6, 704–708, doi:10.3762/bjoc.6.80
- bacteria are referred to as non-typable H. influenzae (NTHi) [5][6]. This structural diversity is a good defence mechanism against the human acquired immune system, and NTHi often cause repetitive infections. Another way used by H. influenzae to avoid the human immune system seems to be molecular mimicry
Graphical Abstract
Figure 1: The H. influenzae outer core target structure.
Scheme 1: i. BH3, Bu2BOTf, THF/CH2Cl2, 85%; ii. TBDMSCl, pyridine, CH2Cl2, 90%; iii. TBDMSCl, pyridine, 92%; ...
Scheme 2: i. PhCH(OMe)2, CSA; ii. NaBH3CN, HCl/Et2O, THF, 80%; iii. NIS/AgOTf, CH2Cl2, 83%; iv. a) NaOMe, MeO...
Scheme 3: i. NIS/AgOTf, CH2Cl2, 77%; ii. a) H2S, pyridine, Et3N; b) CbzCl, pyridine, CH2Cl2, 91%; iii. TBAF, ...
Scheme 4: i. NaOMe, MeOH; ii. H2, Pd/C, MeOH/H2O; iii. 21, PivCl, pyridine, MeCN; iv. I2, H2O, pyridine; v. D...
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...
(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties
- José L. Jiménez Blanco,
- Fernando Ortega-Caballero,
- Carmen Ortiz Mellet and
- José M. García Fernández
Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20
- homo-oligomers A cyclic array of desired ring size and defined secondary structure of alternating carbohydrate moieties and amide groups might conceivably lead to exquisite specificity of recognition and catalysis. One application of this concept is the mimicry of cyclodextrin inclusion complexes. Thus
Graphical Abstract
Figure 1: Schematic representation of sugar aminoacids (SAAs) and (pseudo)amide oligosaccharide mimetics.
Figure 2: Natural SAAs structures and natural nucleosidic antibiotics.
Scheme 1: Synthetic route to the target amide-linked sialooligomers. (a) Fmoc-Cl, NaHCO3, H2O, dioxane, 0 °C....
Figure 3: The general structure of glycoamino acids and their corresponding oligomers.
Figure 4: Conformational analysis of the β(1→2)-amide-linked glucooligomer 9.
Figure 5: Short oligomeric chains of C-glycosyl D-arabino THF amino acid oligomers.
Figure 6: (A) Stereoview of the minimized structure of compound 16 (produced by a 500 ps simulation) that mos...
Figure 7: Structures of linear oxetane-β- and δ-SAA homo-oligomers 19–20.
Figure 8: 10-Membered ring H-bonds in compound 21 consistent with NMR and modelling investigations.
Figure 9: General structure of carbopeptoid-oligonucleotide conjugates.
Figure 10: Protected derivatives of 2,6-diamino-2,6-dideoxy-β-D-glucopyranosyl carboxylic acid 22 and 23.
Figure 11: Cyclic homo-oligomers containing glucopyranoid-SAAs.
Scheme 2: Strategy for solid-phase synthesis of cyclic trimers and tetramers containing pyranoid δ-SAAs.
Figure 12: Cyclic tetramers of L-rhamno- and D-gulo-configured oxetane-SAAs.
Figure 13: Aminoglycosidic antibiotics of the glycocinnamoylspermidine family.
Scheme 3: Synthesis of (thio)trehazoline, via triflate, from β-hydroxy(thio)urea.
Figure 14: Approaches to access pseudoamide-type oligosaccharide mimics.
Figure 15: Calystegine B2 analogues 38 and 39 with urea-linked disaccharide structure.
Figure 16: Rotameric equilibrium shift of 40 by formation of a bidentate hydrogen bond.
Figure 17: Nucleotide analogues with thiourea and S-methylisothiouronium linkers.
Scheme 4: Retrosynthetic approach to synthesize thiourea-linked glycooligomers.
Figure 18: Rotameric equilibria for β-(1→6)-thiourea-linked glucodimer 41.
Figure 19: Schematic representation of (a) cyclodextrin (CDs) and (b) cyclotrehalan (CTs) family members.
Scheme 5: Synthesis of guanidine-linked pseudodisaccharides via carbodiimide.
Figure 20: β(1→6)-Guanidine-linked pseudodi- and pseudotrisaccharides 47 and 48.
Scheme 6: Synthesis of N-benzylguanidine-linked CT2 50.
Figure 21: Structure of RNG and DNG.
Figure 22: Preparation of Fmoc-guanidinium derivatives.
Figure 23: Structures of the homo-oligomeric RNG derivatives 51–55.
Figure 24: Phosphoramidite building block 56.
Figure 25: Structures of DNGs 57–65.
Figure 26: Structure of the phosphoramidite building block 66.
