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Search for "DABCO" in Full Text gives 108 result(s) in Beilstein Journal of Organic Chemistry.
Cation affinity numbers of Lewis bases
- Christoph Lindner,
- Raman Tandon,
- Boris Maryasin,
- Evgeny Larionov and
- Hendrik Zipse
Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163
- values are about 70 to 80 kJ/mol smaller than the respective BHCA values (e.g., for pyridine (1) or triphenylphosphane (89)). Moreover, some of the weakest Lewis bases considered here such as DABCO (44) are not sufficently basic to form covalently bound adducts with trityl cations. The TCA values
- calculated for these systems thus represent the reaction enthalpies for the formation of ion-dipole complexes. Aside from DABCO this is the case for 345, 45, and 347. The C–N bond distances of the energetically best conformations of these complexes range from 2.8 Å to 4.0 Å. As a reference bond length the C
- –N distance in pyridine-trityl adduct (1TT), which amounts to 1.57 Å, can be used. A slightly increased C–N bond length can be found for the TCA-adduct of quinuclidine 53 (1.76 Å), which is in distinct contrast to the structurally similar DABCO. It should be added that all other electrophiles
Graphical Abstract
Scheme 1: Reactions for the methyl cation affinity (MCA) of a neutral Lewis base (1a), an anionic Lewis base ...
Figure 1: MCA values of monosubstituted amines of general formula Me2N(CH2)nH (n = 1–7, in kJ/mol).
Scheme 2: Systematic dependence of MCA.
Scheme 3: Trends in amine MCA values.
Figure 2: Eclipsing interactions in the best conformation of N+Me(iPr)3 (16Me) (left), and the corresponding ...
Scheme 4: General expression for the chain-length dependence of MCA values.
Figure 3: MCA values of monosubstituted phosphanes of general formula Me2P(CH2)nH (n = 1–8, in kJ/mol).
Figure 4: MCA values of monosubstituted phosphanes of general formula PMe2(CH(CH2)n+1) (n = 1–8, in kJ/mol).
Figure 5: The MCA values of n-butyldiphenylphosphane (102) and its (αα-/ββ-/γγ-) dimethylated analogues.
Figure 6: MCA values of phosphanes Me2P–NR2 with cyclic and acyclic amine substituents.
Figure 7: MCA values of phosphanes PMe2R connected to α,α- and β,β-position of nitrogen containing cyclic sub...
Scheme 5: Reactions for the benzhydryl cation affinity (BHCA) of a Lewis base (5a) and pyridine (5b).
Figure 8: Comparison of BHCA values (kJ/mol) and nucleophilicity parameters N for sterically unbiased pyridin...
Scheme 6: Reactions for the trityl cation affinity (THCA) of a Lewis base (6a) and pyridine (6b).
Figure 9: Comparison of MCA, BHCA, and TCA values of selected Lewis bases.
Scheme 7: Correlations of BHCA/TCA values with the respective MCA data for sterically unbiased systems (exclu...
Figure 10: Scheme for the angle d(RXRR) measurements.
Scheme 8: Reactions for the Mosher's cation affinity (MOSCA) of a Lewis base.
Scheme 9: Reactions for the acetyl cation affinity (ACA) of a Lewis base (9a) and pyridine (9b).
Figure 11: Structure of the acetylated pyridine 380 (380Ac).
Scheme 10: Reaction for the Michael-acceptor affinity (MAA) of a Lewis base.
Figure 12: Inverted reaction free energies for the addition of N- and P-based Lewis bases to three different M...
Figure 13: Correlation between MCA values and affinity values towards three different Michael acceptors.
Scheme 11: (a) General definition for a methyl cation transfer reaction between Lewis bases LB1 and LB2, and (...
Figure 14: The energetically best conformations of Pn-Bu3 (120_1, top) and (120_2, bottom).
Figure 15: Relative order of the conformations 120_1 to 120_7 depending on the level of theory.
Figure 16: The structure of the energetically best conformations of 120Me.
Organocatalytic asymmetric allylic amination of Morita–Baylis–Hillman carbonates of isatins
- Hang Zhang,
- Shan-Jun Zhang,
- Qing-Qing Zhou,
- Lin Dong and
- Ying-Chun Chen
Beilstein J. Org. Chem. 2012, 8, 1241–1245, doi:10.3762/bjoc.8.139
- catalysis of DABCO. No desired reaction occurred for phthalimide [25] or N-allyl p-toluenesulfonamide [27], which has been successfully applied in the asymmetric amination of MBH carbonates derived from aryl aldehydes. Pleasingly, the reaction took place smoothly to afford product 4a when hydroxylamine 3a
Graphical Abstract
Scheme 1: Allylic amination of MBH carbonates of isatins to access 3-amino-2-oxindoles.
Scheme 2: Synthetic transformations of multifunctional product 4d.
Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles
- Pavol Jakubec,
- Dane M. Cockfield,
- Madeleine Helliwell,
- James Raftery and
- Darren J. Dixon
Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64
- methylene or methine carbon acids with nitro olefins in the presence of DABCO (20–30 mol %) in THF (Scheme 2). Where diastereoisomers were created in the Michael addition step and stereocontrol was poor, the diastereomeric mixtures were recrystallised to afford single diastereomers 6a, b, e. The relative
Graphical Abstract
Figure 1: Biologically active natural products and drugs containing the piperidine ring.
Scheme 1: A general strategy to 5-nitropiperidin-2-ones and related heterocycles.
Scheme 2: The synthesis of Michael adduct model substrates for the nitro-Mannich/lactamisation cascade.
Scheme 3: Nitro-Mannich/lactamisation cascade with in situ formed imines.
Figure 2: Cyclic imines employed in nitro-Mannich/lactamisation cascade.
Scheme 4: Nitro-Mannich/lactamisation cascade of diastereomeric Michael adducts 6a, 6a’’ with cyclic imine 5a....
Scheme 5: Nitro-Mannich/lactamisation cascade with cyclic imines. aDiastereomeric ratio in a crude reaction m...
Scheme 6: Possible explanations for the observed high stereoselectivities in the nitro-Mannich/lactamisation ...
Scheme 7: Thermodynamically-driven epimerisation of 5-nitropiperidin-2-ones 2m and 2m’.
Figure 3: Thermodynamically driven epimerisation of 5-nitropiperidin-2-ones 2m and 2m’; identical diastereome...
Scheme 8: One-pot three/four-component enantioselective Michael addition/nitro-Mannich/lactamisation cascade.
Scheme 9: Protodenitration of 5-nitropiperidin-2-ones.
Scheme 10: Various reductions of denitrated heterocycles.
Amines as key building blocks in Pd-assisted multicomponent processes
- Didier Bouyssi,
- Nuno Monteiro and
- Geneviève Balme
Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163
- (after removal of excess acrylic acid) with the aid of an oligomeric alkyl carbodiimide 44 (Scheme 19) [19]. Interestingly, Willis and coworkers have shown that aryl N-aminosulfonamides may be accessed by three-component coupling of aryl iodides, hydrazines, and DABCO·(SO2)2 as a convenient source of
Graphical Abstract
Scheme 1: Synthesis of substituted amides.
Scheme 2: Synthesis of ketocarbamates and imidazolones.
Scheme 3: Access to β-lactams.
Scheme 4: Access to β-lactams with increased structural diversity.
Scheme 5: Synthesis of imidazolinium salts.
Scheme 6: Access to the indenamine core.
Scheme 7: Synthesis of substituted tetrahydropyridines.
Scheme 8: Synthesis of more substituted tetrahydropyridines.
Scheme 9: Synthesis of chiral tetrahydropyridines.
Scheme 10: Preparation of α-aminonitrile by a catalyzed Strecker reaction.
Scheme 11: Synthesis of spiroacetals.
Scheme 12: Synthesis of masked 3-aminoindan-1-ones.
Scheme 13: Synthesis of homoallylic amines and α-aminoesters.
Scheme 14: Preparation of 1,2-dihydroisoquinolin-1-ylphosphonates.
Scheme 15: Pyrazole elaboration by cycloaddition of hydrazines with alkynones generated in situ.
Scheme 16: An alternative approach to pyrazoles involving hydrazine cycloaddition.
Scheme 17: Synthesis of pyrroles by cyclization of propargyl amines.
Scheme 18: Isoindolone and phthalazone synthesis by cyclization of acylhydrazides.
Scheme 19: Sultam synthesis by cyclization of sulfonamides.
Scheme 20: Synthesis of sulfonamides by aminosulfonylation of aryl iodides.
Scheme 21: Pyrrolidine synthesis by carbopalladation of allylamines.
Scheme 22: Synthesis of indoles through a sequential C–C coupling/desilylation–coupling/cyclization reaction.
Scheme 23: Synthesis of indoles by a site selective Pd/C catalyzed cross-coupling approach.
Scheme 24: Synthesis of isoindolin-1-one derivatives through a sequential Sonogashira coupling/carbonylation/h...
Scheme 25: Synthesis of pyrroles through an allylic amination/Sonogashira coupling/hydroamination reaction.
Scheme 26: Synthesis of indoles through a Sonogashira coupling/cyclofunctionalization reaction.
Scheme 27: Synthesis of indoles through a one-pot two-step Sonogashira coupling/cyclofunctionalization reactio...
Scheme 28: Synthesis of α-alkynylindoles through a Pd-catalyzed Sonogashira/double C–N coupling reaction.
Scheme 29: Synthesis of indoles through a Pd-catalyzed sequential alkenyl amination/C-arylation/N-arylation.
Scheme 30: Synthesis of N-aryl-2-benzylpyrrolidines through a sequential N-arylation/carboamination reaction.
Scheme 31: Synthesis of phenothiazine derivatives through a one-pot palladium-catalyzed double C–N arylation i...
Scheme 32: Synthesis of substituted imidazolidinones through a palladium-catalyzed three-component reaction of...
Scheme 33: Synthesis of 2,3-diarylated amines through a palladium-catalyzed four-component reaction involving ...
Scheme 34: Synthesis of rolipram involving a Pd-catalyzed three-component reaction.
Scheme 35: Synthesis of seven-membered ring lactams through a Pd-catalyzed amination/intramolecular cyclocarbo...
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 subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts
- Kari Raatikainen,
- Massimo Cametti and
- Kari Rissanen
Beilstein J. Org. Chem. 2010, 6, No. 4, doi:10.3762/bjoc.6.4
- of iodo- and nitrobenzenes [29][30]. In our recent studies [33], we have shown that 1-iodo-3,5-dinitrobenzene forms surprisingly strong C–I···N halogen bonds (23% shorter than the sum of standard VDW radii [17]) with 1,4-diazabicyclo[2.2.2]octane (DABCO). One of the main challenges in supramolecular
- previous study on co-crystals of 1-iodo-3,5-dinitrobenzene and DABCO (1,4-diazabicyclo[2.2.2]octane) [33]. Thus, we prepared X-ray quality crystals of 13 from an ethyl acetate solution of 3-iodopyridine and 5-nitroisophthalic acid in 2 : 1 molar ratio. Despite the stoichiometry employed in the
Graphical Abstract
Scheme 1: The chemical structures of the salts 1–13.
Figure 1: X-ray structure of 4-IPhNH3Cl (1) with numbering for selected atoms (a) and the packing scheme view...
Figure 2: Interaction contacts in 4-IPhNH3Cl (1; a), 4-BrPhNH3Cl (2; b), 4-ClPhNH3Cl (3; c) and 4-FPhNH3Cl (4...
Figure 3: X-ray structure of 4-IPhNH3Br (5) with selected numbering scheme (a) and the packing scheme viewed ...
Figure 4: X-ray structure of 4-IPhNH3H2PO4 (6) with selected numbering scheme of the asymmetric unit and the ...
Figure 5: X-ray structure of 3-IPyBnCl (9) with the selected numbering scheme of the asymmetric unit (a) and ...
Figure 6: X-ray structure of 3-IPyHCl (10) with the selected numbering scheme of the asymmetric unit (a) and ...
Figure 7: X-ray structure of 3-IPyH-5-NIPA (13) with selected numbering scheme of the asymmetric unit (a). A ...
Sordarin, an antifungal agent with a unique mode of action
- Huan Liang
Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31
- in MeCN afforded a product of excellent quality that was directly utilized in the next step. Then, treatment of crude 93 in acrylonitrile with a catalytic amount of DABCO gave the Baylis-Hillman product 94. Preparation of the Danishefsky-like diene 95 by treatment of 94 with Hunig’s base and TES
Graphical Abstract
Figure 1: Therapeutic antifungal agents.
Figure 2: Structure of sordarin (1) and sordaricin (2).
Scheme 1: Kato’s retrosynthetic plan.
Scheme 2: Synthesis of cyclopentadiene 13.
Scheme 3: Synthesis of sordaricin methyl ester.
Scheme 4: Mander’s retrosynthetic plan.
Scheme 5: Synthesis of iodo compound 27.
Scheme 6: Synthesis of sordaricin (2).
Scheme 7: Retrosynthesis of sordarin and sordaricin.
Scheme 8: Synthesis of ketone 43.
Scheme 9: Synthesis of β-keto ethyl ester 45.
Scheme 10: Synthesis of tetracyclic framework 52.
Scheme 11: Synthesis of sordaricin and sordarin.
Figure 3: Modifications of glycosyl part.
Scheme 12: Simplified model of sordarin.
Scheme 13: Synthesis of cyclopentane analog precursors.
Scheme 14: Synthesis of six cyclopentane analogs.
Scheme 15: Retrosynthetic plan of sordarin analog.
Scheme 16: Synthesis of sordarin analog 98.
Scheme 17: Synthesis of sordarin analog 103.
Hydrogen bonding patterns in the cocrystals of 5-nitrouracil with several donor and acceptor molecules
- Reji Thomas,
- R. Srinivasa Gopalan,
- G. U. Kulkarni and
- C. N. R. Rao
Beilstein J. Org. Chem. 2005, 1, No. 15, doi:10.1186/1860-5397-1-15
- evaporation of a solution of I in respective solvents. Cocrystals of I with non-solvent guests – piperazine, N,N'-dimethylpiperazine, 3-aminopyridine and diazabicyclo [2.2.2]octane (DABCO)- were made by solvothermal method. In all the cases, the compound I and the guest molecule were taken in 1:1 ratio in
- example of such stacking has been found in the cocrystal of I with DABCO and water (molar composition, 2:2:5), as shown in Figure 8. The structure contains cyclic dimers of nitrouracil (see inset of Figure 8) formed through N-H...O interactions (H(22A)...O(12), 1.878(3) Å and H(12A)...O(22), 2.189(3) Å
- ), arranged in the form of parallel set of tapes. The nitrouracil tapes are held between sheets of the DABCO molecules, which in turn are covered by layers of water molecules. These supramolecular assemblies get rotated along the a axis by 90° alternately. There is extensive hydrogen bonding between DABCO and
Graphical Abstract
Scheme 1: Hydrogen bonding patterns of I commonly found in its cocrystals with other molecules. Cyclic N-H......
Figure 1: Dioxane molecules held between the zig-zag rows of I, viewed (a) perpendicular and (b) parallel to ...
Figure 2: Cocrystal of I and piperazine: (a) A molecular layer showing alternating tapes of I and piperazine....
Figure 3: Cocrystal of I and N,N'-dimethylpiperazine: (a) A molecular layer showing alternating chains of I a...
Figure 4: Cocrystal of I and pyridine: A molecular layer showing alternating rows of I and pyridine.
Figure 5: Cocrystal of I and formamide: A molecular layer showing tapes of mixed composition,I and formamide,...
Figure 6: Cocrystal of I, ethanol and water: (a) A molecular layer showing tapes of mixed compositions- tapes...
Figure 7: Cocrystal of I and 3-aminopyridine: Stacks of molecular tapes arranged in alternating parallel and ...
Figure 8: Cocrystal of I and DABCO: A view along the diagonal of the ab plane showing the supramolecular asse...
Figure 9: (a) Tetrahedral pentamers of water in the ab plane forming a nearly square arrangement (b) Hydrogen...
Figure 10: A tetrahedron pentamer of water. The O...O distances and H-O-H angles are indicated in the inset.
