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Search for "lactate" in Full Text gives 36 result(s) in Beilstein Journal of Organic Chemistry.
Concise, stereodivergent and highly stereoselective synthesis of cis- and trans-2-substituted 3-hydroxypiperidines – development of a phosphite-driven cyclodehydration
- Peter H. Huy,
- Julia C. Westphal and
- Ari M. P. Koskinen
Beilstein J. Org. Chem. 2014, 10, 369–383, doi:10.3762/bjoc.10.35
- (commercial trade names Halocur® (lactate salt) and Stenorol® (hydrobromide salt)) [22]. Other relevant examples are 3-hydroxypipecolic acids, which serve as (conformationally restricted) substitutes of proline and serine [23][24] and have been incorporated into diverse bioactive peptidomimetics [25][26], and
Graphical Abstract
Figure 1: Natural products and other bioactive piperidine derivatives of type B.
Figure 2: Retrosynthetic analysis of piperidines B (X = OH or leaving group, PG = protecting group).
Scheme 1: Synthesis of the protected amino acids 2. (a) KOH for 1b. b) PG–X = Cbz–Cl (1a–c), Boc2O (1d).
Scheme 2: Synthesis of hydroxy ketones 7 (R = Me (a), Bn (b), Ph (c) and EtSMe (d); PG = Cbz (a–c), Boc (d)).
Scheme 3: Synthesis of amides 5e and 5f and ketone 7e.
Scheme 4: Synthesis of amino alcohols syn-9a–d and oxazolidinone 10a. (for 7a–c conditions A: H2 (1 atm), Pd/...
Scheme 5: Competition between the Michaelis–Arbuzow process and the desired cyclodehydration of amino alcohol...
Scheme 6: Initial synthesis of the trans-piperidinol 11a in diminished enantiopurity. aThe amino alcohol 9a o...
Scheme 7: Synthesis of trans-piperidinol 11a in excellent ee.
Scheme 8: Synthesis of L-733,060·HCl.
Biosynthesis of rare hexoses using microorganisms and related enzymes
- Zijie Li,
- Yahui Gao,
- Hideki Nakanishi,
- Xiaodong Gao and
- Li Cai
Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281
- reduction of pyruvate by L-lactate dehydrogenase (EC 1.1.1.27) [55]. Alternatively, Itoh et al. discovered that DTEase from Pseudomonas sp. ST-24 was a promising enzyme, which was active not only on D-ketohexoses but also on L-ketohexoses [56]. Therefore, L-tagatose was successfully prepared by immobilized
Graphical Abstract
Scheme 1: Synthesis of D-tagatose from D-galactose using L-arabinose isomerase.
Scheme 2: Synthesis of D-psicose from D-fructose using D-tagatose 3-epimerase/D-psicose 3-epimerase.
Figure 1: The active site in D-psicose 3-epimerase (DPEase) in the presence of D-fructose, showing the metal ...
Scheme 3: Enzymatic synthesis of D-psicose using aldolase FucA.
Scheme 4: Proposed pathway of the D-sorbose synthesis from galactitol or L-glucitol.
Scheme 5: Simultaneous enzymatic synthesis of D-sorbose and D-psicose.
Scheme 6: Biosynthesis of L-tagatose.
Scheme 7: Preparative-scale synthesis of L-tagatose and L-fructose using aldolase.
Scheme 8: Biosynthesis of L-fructose.
Scheme 9: Preparative-scale synthesis of L-fructose using aldolase RhaD.
Scheme 10: Chemoenzymatically synthesis of 1-deoxy-L-fructose [8].
Scheme 11: Potential enzymes (isomerases) for the bioconversion of D-psicose to D-allose.
Scheme 12: Three-step bioconversion of D-glucose to D-allose.
Scheme 13: Biosynthesis of L-glucose.
Scheme 14: Enzymatic synthesis of L-talose and D-gulose.
Scheme 15: Enzymatic synthesis of L-galactose.
Scheme 16: Enzymatic synthesis of L-fucose.
Scheme 17: Synthesis of allitol from D-fructose using a multi-enzyme system.
Scheme 18: Biosynthesis of D-talitol via C-2 reduction of rare sugars.
Scheme 19: Biosynthesis of L-sorbitol via C-2 reduction of rare sugars.
Thermotropic and lyotropic behaviour of new liquid-crystalline materials with different hydrophilic groups: synthesis and mesomorphic properties
- Alexej Bubnov,
- Miroslav Kašpar,
- Věra Hamplová,
- Ute Dawin and
- Frank Giesselmann
Beilstein J. Org. Chem. 2013, 9, 425–436, doi:10.3762/bjoc.9.45
- . Recently, two series of chiral liquid-crystalline materials (similar to those presented in this work) with chiral lactate group or lactic acid derivative have been synthesized and studied [30][31][32]. These materials (with the same molecular core and nonchiral chain as TL4) possess different thermotropic
Graphical Abstract
Figure 1: Microphotographs of the textures obtained in the polarized optical microscope on planar samples (PS...
Figure 2: DSC plot on heating/cooling runs (indicated by horizontal arrows) for indicated nonchiral compounds...
Figure 3: DSC plot on heating/cooling runs (indicated by horizontal arrows) for indicated chiral compounds: T...
Figure 4: Temperature dependence of the layer spacing d, and intensity of the scattered X-ray beam measured a...
Figure 5: Schematic contact preparation used for detection and study of lyotropic behaviour.
Figure 6: Microphotographs of the contact preparation of TL4 with diethylene glycol (DG): (a) texture of the ...
Scheme 1: General procedure for the synthesis of (a) nonchiral 4'-(2,5,8,11-tetraoxatridecan-13-yloxy)bipheny...
Scheme 2: General procedure for synthesis of 2-(1-(6-(4'-(6-(3-hydroxy-2-(hydroxymethyl)-2-methylpropoxy)hexy...
Scheme 3: General procedure for the synthesis of chiral (E)-2-methyl-2-((2-(2-(2-(4-((4-((4-(2-methylbutoxy)p...
Dimerization of a cell-penetrating peptide leads to enhanced cellular uptake and drug delivery
- Jan Hoyer,
- Ulrich Schatzschneider,
- Michaela Schulz-Siegmund and
- Ines Neundorf
Beilstein J. Org. Chem. 2012, 8, 1788–1797, doi:10.3762/bjoc.8.204
- assays measuring the amount of lactate dehydrogenase (LDH) released from the cells when the membrane becomes prone to leaking. In the case of MCF-7, high levels of extracellular LDH even after 1 h incubation with 30 µM (sC18)2 attested to a high extent of membrane destabilization, which eventually leads
Graphical Abstract
Figure 1: Flow cytometric uptake studies of carboxyfluorescein-labeled (sC18)2 in HEK-293 (human embryonic ki...
Figure 2: Top: Fluorescence microscopic images of unfixed HEK-293 cells after 30 min incubation with 1 µM CF-...
Figure 3: Cell viability of different cell lines after 24 h incubation with (sC18)2 at different concentratio...
Figure 4: Cell lysis of HEK-293 cells induced by (sC18)2 after 1 h incubation. Experiments were conducted in ...
Scheme 1: Synthesis of (sC18)2 bioconjugates (a) and chemical structures of the coupled anti-tumor agents (b)...
Figure 5: Chromatogram and ESI-MS of purified Cym2-GFL-(sC18)2. The gradient was 10→60% acetonitrile in water...
Figure 6: Circular dichroism spectra of the (sC18)2 conjugates. Spectra were acquired in 10 mM phosphate buff...
Figure 7: Cell viability of (a) HT-29 and (b) MCF-7 cells after 24 h incubation with the (sC18)2 conjugates a...
Figure 8: Brightfield microscopic images of unfixed HT-29 cells after 24 h incubation with the (sC18)2 conjug...
Figure 9: Cell lysis of (a) HT-29 and (b) MCF-7 cells induced by the (sC18)2 conjugates at different concentr...
Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids
- M. Isabel Burguete,
- Eduardo García-Verdugo and
- Santiago V. Luis
Beilstein J. Org. Chem. 2011, 7, 1347–1359, doi:10.3762/bjoc.7.159
- , enhanced selectivity. Some classical examples are provided by the work of Baiker [38][39]. Thus, initial studies focused on the enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate over cinchonidine (CD) modified Pt/Al2O3. The results obtained showed that a dramatic increase in both
Graphical Abstract
Scheme 1: Hydrogenation of ethyl pyruvate.
Scheme 2: Hydrogenation of dimethyl itaconate.
Scheme 3: a) Enantioselective hydrogenation of N-(1-phenylethylidene)aniline in IL–CO2; b) Enantioselective h...
Scheme 4: Selective hydroformylation with a silica supported Rh catalyst.
Scheme 5: Enantioselective hydroformylation of styrene.
Scheme 6: Enantioselective hydrovinylation of styrene.
Scheme 7: Enantioselective cyclopropanation of styrene catalyzed by supported Cu–BOX, Cu–PyOX and Rh–PyBOX ca...
Scheme 8: Continuous hydrogenation of acetophenone coupled with the kinetic resolution of the product.
Scheme 9: Kinetic resolution of phenylethanol using CALB immobilized in ILs and supported ILs.
Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor
- María Martín-Rodríguez,
- Carmen Nájera,
- José M. Sansano,
- Abel de Cózar and
- Fernando P. Cossío
Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111
- endo-diastereoselective synthesis of the key precursor 5a (HetAr = 2-thienyl), of the antiviral agent 1 (96% de), was achieved by our group from imine 6a (HetAr = 2-thienyl; R1 = Me) in the presence of the acrylate derived from (R)-methyl lactate [19]. However, the most straightforward, and also faster
Graphical Abstract
Figure 1: More active GSK HCV inhibitors.
Scheme 1: Retrosynthetic analysis of antiviral structures.
Figure 2: Chiral phosphoramidites tested in this study.
Scheme 2: Optimization of the reaction conditions for the synthesis of the key intermediate 5b.
Scheme 3: Preparation of the enantiomerically enriched 5b.
Scheme 4: Total synthesis of antiviral agent 2b.
Figure 3: Gibbs activation energy and main geometrical features of the computed ylide and transition structur...
A practical two-step procedure for the preparation of enantiopure pyridines: Multicomponent reactions of alkoxyallenes, nitriles and carboxylic acids followed by a cyclocondensation reaction
- Christian Eidamshaus,
- Roopender Kumar,
- Mrinal K. Bera and
- Hans-Ulrich Reissig
Beilstein J. Org. Chem. 2011, 7, 962–975, doi:10.3762/bjoc.7.108
- pyridine but also pyrimidine derivatives with lactic acid based side chains should be accessible. O-TBS-protected lactic nitrile 63 was prepared following a literature procedure in four steps starting from enantiopure methyl lactate [48]. The scope of the multicomponent reaction with respect to lactic acid
Graphical Abstract
Scheme 1: Preparation of β-ketoenamides and subsequent cyclocondensation to 4-hydroxypyridines. a) Et2O, −40 ...
Scheme 2: Mechanistic rational for the formation of β-ketoenamides 16.
Scheme 3: Reaction of proline derivative 45 and formation of β-ketoenamide 47 and enolester 48.
Figure 1: 1H NMR spectra of 49 and the mixture of diastereoisomers 49 and 49’.
Scheme 4: Synthesis of pyrid-4-yl nonaflate 52.
Scheme 5: O-Methylation of pyridine derivatives 22 and 30 followed by desilylation.
Scheme 6: Formation of 5-alkoxypyrimidines from β-alkoxy-β-ketoenamides.
Catalysis: transition-state molecular recognition?
- Ian H. Williams
Beilstein J. Org. Chem. 2010, 6, 1026–1034, doi:10.3762/bjoc.6.117
- by lactate dehydrogenase [2]. The abstract for this workshop presentation began with the following sentence: The key to understanding of the fundamental processes of catalysis is the transition state; indeed, “catalysis is a transition-state molecular recognition event”. The present paper discusses
Graphical Abstract
Figure 1: Free energy profiles for reactions of substrate S uncatalysed and catalysed by enzyme E, showing ho...
Scheme 1: SN2 methyl transfer from SAM to catechol catalysed by COMT.
Figure 2: Energetic analysis of the compression hypothesis for enzyme-catalysed methyl transfer.
Figure 3: Catalyst design for methyl transfer: (a) the reaction to be catalysed; (b) dipoles favourably align...
Scheme 2: SN2 methyl transfer (a) uncatalysed and (b) within a cryptand cavity.
Figure 4: Free energy analysis of COMT catalysis.
Scheme 3: Formation of glycosyl-enzyme covalent intermediate COV.
Figure 5: Conformational change of the xylose ring from chair (via envelope) with long OYHY…Oring hydrogen bo...
Figure 6: AM1/OPLS potentials of mean force for formation of glycosyl-enzyme covalent intermediate between 4-...
Figure 7: Hydrogen-bond distances HY…Oring (red) and HY…Onuc (blue) to boat conformer of RC, TS and glycosyl-...
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...
Convenient method for preparing benzyl ethers and esters using 2-benzyloxypyridine
- Susana S. Lopez and
- Gregory B. Dudley
Beilstein J. Org. Chem. 2008, 4, No. 44, doi:10.3762/bjoc.4.44
- (entry 7, 84%) and methyl lactate (3e, 79%) verify compatibility with esters and carbamates. Note that the benzylation of N-Boc-serine methyl ester (3d) compares favourably to analogous reactions reported previously [24], because the neutral reaction conditions described herein are compatible with the
Graphical Abstract
Figure 1: Benzyl bromide, benzyl trichloroacetimidate, and 2-benzyloxy-1-methylpyridinium triflate (1).
Scheme 1: Published syntheses of benzyl esters from alcohols using neutral reagent 1; other benzylation proce...
Scheme 2: Preparation of 2-benzyloxypyridine (2).
Scheme 3: Synthesis of a benzyl ester from a carboxylic acid.
Scheme 4: Representative synthesis of a halobenzyl ether under neutral conditions.
Inversion symmetry and local vs. dispersive interactions in the nucleation of hydrogen bonded cyclic n-mer and tape of imidazolecarboxamidines
- Sihui Long,
- Venkatraj Muthusamy,
- Peter G. Willis,
- Sean Parkin and
- Arthur Cammers
Beilstein J. Org. Chem. 2008, 4, No. 23, doi:10.3762/bjoc.4.23
- crystalline phase. Regarding less condensed states, optically pure gas phase methyl lactate favors the tetramer over dimers more than the racemic mixture [44]. The lack of the energetically competitive heterochiral dimer in the optically pure mixture could have produced that result. With all things equal
Graphical Abstract
Figure 1: 1: An intuitive prediction regarding the relationship between crude hydrogen bond donor/acceptor di...
Figure 2: Facile syntheses of imidazole carboxamidines from commercial imidazoles and carbodiimides furnished...
Figure 3: The NCNC dihedral angle, θ, between the hydrogen bond donors and acceptors, was assigned values bet...
Figure 4: Stereoview of Dimer 5c. This dimer stacked imidazole rings with R1 pointing in opposite directions.
Figure 5: Stereoview of trimer 6b.
Figure 6: Stereoview of tetramer 9a.
Figure 7: Stereoview of linear hydrogen bond tape 11a.
Figure 8: The calculated (rhf/6-311+g(d,p)) potential energy (kcal/mol) of N,N'-dimethyl-1H-imidazole-1-carbo...
Figure 9: A Flow chart for the calculation of the energies of the n-mers minus the effects of packing and sub...
Figure 10: Icons correspond to those in Figure 8. Crosses indicate structures with aromatic groups. The calculated (rh...
Figure 11: The icon legend is identical to Figure 8 and Figure 10. The Y-axis from Figure 8 energies (θ only) and the X-axis from Figure 10 ener...
