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Search for "quinone" in Full Text gives 113 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of mesomeric betaine compounds with imidazolium-enolate structure
- Nina Gonsior,
- Fabian Mohr and
- Helmut Ritter
Beilstein J. Org. Chem. 2012, 8, 390–397, doi:10.3762/bjoc.8.42
- ) with different halide-containing quinone derivatives and subsequent hydrolysis [11]. Since the quaternization reaction is very common for imidazole chemistry, e.g., synthesis of ionic liquids, we investigated the quaternization reaction of three different imidazole compounds with tetrabromo-1,4
Graphical Abstract
Scheme 1: Reaction of p-bromanil (1) with 1-butylimidazole (2).
Figure 1: 1H NMR spectrum of mesomeric betaine 3.
Figure 2: 13C NMR spectrum of dipole 3.
Figure 3: Solid-state molecular structure of compound 3. Selected bond distances [Å]: O(1)–C 1.228(4), O(2)–C...
Figure 4: Formation of molecular layers in the crystal packing.
Figure 5: Higuchi–Connors phase diagram of 3/m-β-CD complex.
Scheme 2: Mechanism of molecular association of the complex.
Figure 6: Classification of betaine 3.
Scheme 3: Synthesis of polymer 6 and oligomer 7 based on imidazolium-enolate structures.
Figure 7: Thermogravimetric analyses of polymer networks 6a–c and oligomers 7a,b.
Self-assembly of Ru4 and Ru8 assemblies by coordination using organometallic Ru(II)2 precursors: Synthesis, characterization and properties
- Sankarasekaran Shanmugaraju,
- Dipak Samanta and
- Partha Sarathi Mukherjee
Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34
- , 4H, H4-quinone), 5.75 (d, J = 6.0 Hz, 16H, Hβ-cymene), 2.86–2.79 (septet, 8H, H2-cymene), 2.22 (s, 24H, H3-cymene), 1.31 (d, 48H, H1-cymene); 19F NMR (376.5 MHz, CD3CN) δ −79.08; 13C NMR (100 MHz, CD3NO2) δ 183.92, 140.62, 134.75, 131.45, 124.09, 122.92, 119.74, 103.76, 99.10, 84.88, 83.65, 79.47
Graphical Abstract
Scheme 1: Possible octanuclear prism and tetranuclear macrocycle resulting from the combination of a tetraden...
Scheme 2: Formation of the tetranuclear complexes (2a and 2b) upon the reaction of Ru(II)2 based acceptors 1a...
Figure 1: 1H (left) and 19F (right) NMR spectra of tetranuclear macrocycle 2a recorded in CD2Cl2–CD3OD with p...
Figure 2: ESIMS spectrum of the macrocycle 2a recorded in acetonitrile. Inset: Experimentally observed isotop...
Figure 3: A ball and stick representation of 2a with atom numbering. Color code: Ru = green; O = red; N = blu...
Scheme 3: Formation of an octanuclear macrocycle 2c upon reaction of Ru(II)2-based acceptors 1c with imidazol...
Figure 4: 1H (left) and 19F (right) NMR spectrum of the macrocycle 2c recorded in CD3CN with the peak assignm...
Figure 5: Side (left) and top (right) view of the energy-minimized structures of the octanuclear macrocycle 2c...
Figure 6: UV–vis absorption spectrum (left) of macrocycles (2a–2c) recorded in CH3CN at 298 K, and cyclic vol...
Predicting the UV–vis spectra of oxazine dyes
- Scott Fleming,
- Andrew Mills and
- Tell Tuttle
Beilstein J. Org. Chem. 2011, 7, 432–441, doi:10.3762/bjoc.7.56
- ; oxazine; TD-DFT; UV–vis; Introduction Oxazine dyes are a subclass of quinone imines, which are all based upon the p-benzoquinone imine or -diimine scaffold. Other important subclasses within the quinone imines include, the azine dyes and thiazine dyes. The structural relationships described are
- Gaussian 09 program [47]. Finally, we have also employed the orbital overlap diagnostic of Tozer et al. in order to assess the CT character in the principal excited states [27]. Quinone imine structural relationships. Numbering and structure of oxazine dyes studied in this work (counterions not shown
Graphical Abstract
Figure 1: Quinone imine structural relationships.
Figure 2: Numbering and structure of oxazine dyes studied in this work (counterions not shown).
Figure 3: Directions of solvated (a) dipole moments and (b) transition moments from origin (0,0,0).
Figure 4: Error between experimental and calculated λmax values for each dye at the different levels of theor...
Figure 5: The orbital overlaps (Λ) for each dye at the different levels of theory investigated. All structure...
Surfactant catalyzed convenient and greener synthesis of tetrahydrobenzo[a]xanthene-11-ones at ambient temperature
- Pravin V. Shinde,
- Amol H. Kategaonkar,
- Bapurao B. Shingate and
- Murlidhar S. Shingare
Beilstein J. Org. Chem. 2011, 7, 53–58, doi:10.3762/bjoc.7.9
- surfactant was sufficient for catalyzing the reaction effectively. In accordance with the literature [15], a plausible mechanistic path for the formation of tetrahydrobenzo[a]xanthen-11-ones can be outlined as follows: nucleophilic addition of 2-naphthol to the aldehyde to give an intermediate ortho-quinone
Graphical Abstract
Scheme 1: Standard model reaction.
Figure 1: Optical micrograph of the reaction mixture. (A) normal view, (B) magnified view. (Scale bar = 2.5 µ...
Figure 2: Schematic diagram representing the role of TTAB.
Synthesis of 2a,8b-Dihydrocyclobuta[a]naphthalene-3,4-diones
- Kerstin Schmidt and
- Paul Margaretha
Beilstein J. Org. Chem. 2010, 6, No. 76, doi:10.3762/bjoc.6.76
- ; quinone monoacetals; Introduction The behaviour of excited 1,2- and 1,4-quinones towards ground-state molecules differs greatly. Whereas the former typically react via H-abstraction by an excited carbonyl group [1], the latter smoothly undergo [2 + 2] cycloaddition to alkenes to afford cyclobutane-type
Graphical Abstract
Scheme 1: Synthesis of 2a,8b-dihydrocyclobuta[a]naphthalene-3,4-diones.
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
- are deprotonated, which leads to lactone ring opening and the formation of a colored quinone conjugated carboxylate structure. The chemosensor discriminated terminal diamines by length: 1,8-diaminooctane (Kass = 1270 M−1) and 1,9-diaminononane (Kass = 2020 M−1) showed the highest binding constants in
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...
Chiral amplification in a cyanobiphenyl nematic liquid crystal doped with helicene-like derivatives
- Alberta Ferrarini,
- Silvia Pieraccini,
- Stefano Masiero and
- Gian Piero Spada
Beilstein J. Org. Chem. 2009, 5, No. 50, doi:10.3762/bjoc.5.50
- twist angles ranging between 42° and 43° for 1–4 and a slightly lower angle, around 40°, for 5. A larger twist angle of 50.1° is found in dihydro[4]helicene quinones 7 and 8, whereas a wider value, 81.7°, is allowed in tetrahydro[4]helicene quinone 6, because of the higher flexibility arising from the
- different behavior is exhibited by derivative 5, which has bulkier TBDMS substituents; one of them is constrained by the proximity of the quinone ring, whereas the other is pointing towards the molecular periphery and is more free. Three structures with similar energy were obtained, differing essentially in
- the larger dimensions of the [4]helicene quinone derivatives, which possess a wider extension of aromatic rings, capable of establishing stronger dispersion interactions with the host molecules. As to the effect of substituents, we can compare the results obtained for the pairs 1–2, 3–4, and 7–8
Graphical Abstract
Figure 1: Schematic structure of a right-handed chiral nematic (cholesteric) phase. Black arrows represent th...
Figure 2: Structures of the dopants investigated.
Figure 3: Geometry of dopants 1–8. Structures were obtained from DFT calculations at the B3LYP/6-31g** level [58]...
Figure 4: Helicity of the molecular surface of derivative 1 along its principal alignment axes in the liquid ...
Studies on polynuclear furoquinones. Part 1: Synthesis of tri- and tetra- cyclic furoquinones simulating BCD/ABCD ring system of furoquinone diterpenoids
- Faruk H. Shaik and
- Gandhi K. Kar
Beilstein J. Org. Chem. 2009, 5, No. 47, doi:10.3762/bjoc.5.47
- of aryl-furyl C–C bond via Suzuki reaction [35] and the generation of the quinone functionality by oxidation of a phenolic intermediate (Figure 2). Retrosynthesis of the molecule showed that the required phenolic compound can easily be achieved in 7–8 steps starting from 2-bromo-3,4-dihydro-1
- acid (TFA) and trifluoroacetic anhydride (TFAA) at room temperature in 71% yield. The phenol 12 was finally oxidized (with Fremy’s salt) [36][37][38] to the o-quinone 13 to complete the synthesis of phenanthro[1,2-b]furan-10,11-dione. The compounds were characterized by usual spectroscopic and
- ), 7.49 (1H, d, J = 2.0 Hz), 7.45 (1H, m), 6.86 (1H, d, J = 2.0 Hz)]. Some biologically active tetra cyclic furoquinone derivatives (isolated from Dan Shen) and synthetic tricyclic furoquinones. Key strategies for development of C-ring with quinone functionality. Retro synthesis of tetra cyclic
Graphical Abstract
Figure 1: Some biologically active tetra cyclic furoquinone derivatives (isolated from Dan Shen) and syntheti...
Figure 2: Key strategies for development of C-ring with quinone functionality.
Figure 3: Retro synthesis of tetra cyclic furoquinone 13.
Scheme 1: Reagents and conditions: i) DDQ (1.5 equiv), dry benzene, reflux, argon atmosphere, 37 h, 83%. ii) ...
Figure 4: Assignment of chemical shifts (1H NMR and 13C NMR) of compound 13.
Scheme 2: Reagents and conditions: i) furan-2-boronic acid (1.2 equiv), Et3N, DMF, Pd(PPh3)4 (2 mol %), 110 °...
Mitomycins syntheses: a recent update
- Jean-Christophe Andrez
Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33
- the p-quinone are called mitosanes or mitosenes depending whether they are at the oxidation state of an indoline (Y1 or Y2 = H) or an indole (Y1 = Y2 = C=C). Compounds bearing an aziridine at C1 and C2 are described specifically as aziridinomitosanes and aziridinomitosenes respectively. Compounds
- possessing a hydroquinone (protected or not) in place of the original quinone are identified by inclusion of the prefix leuco in reference to the Greek word leukos (clear, white) and the lack of intense color usually specific of the corresponding quinone ring. The mitomycins A and C differ only by the
- substituents on the quinone ring and transformation from 6 to 7 is realized by simple treatment with ammonia [23][24]. The mitomycins F, 8, and porfiromycin, 9, are synthesized by methylation of the aziridine of mitomycin A and mitomycin C, respectively. Mitomycin G, 12, mitomycin H, 13, and mitomycin K, 14
Graphical Abstract
Scheme 1: Aziridine containing natural products.
Scheme 2: Mitomycin structures and nomenclature.
Scheme 3: Base catalysed epimerization of mitomycin B.
Scheme 4: Biosynthesis of mitomycin C (MMC) 7.
Scheme 5: Mode of action of mitomycin C.
Scheme 6: The N–C3–C9a disconnection.
Scheme 7: Danishefsky’s Retrosynthesis of mitomycin K.
Scheme 8: Hetero Diels–Alder reaction en route to mitomycins.
Scheme 9: Nitroso Diels–Alder cycloaddition.
Scheme 10: Frank azide cycloadddition.
Scheme 11: Final steps of mitomycin K synthesis. aPDC, DCM; bPhSCH2N3, PhH, 80 °C; cL-selectride, THF, −78 °C; ...
Scheme 12: Naruta–Maruyama retrosynthesis.
Scheme 13: Synthesis of a leucoaziridinomitosane by nitrene cycloaddition. aAlCl3-Et2O; bNaH, ClCH2OMe; cn-BuL...
Scheme 14: Thermal decomposition of azidoquinone 51.
Scheme 15: Diastereoselectivity during the cycloaddition.
Scheme 16: Oxidation with iodo-azide.
Scheme 17: Williams’ approach towards mitomycins.aDEIPSCl, Imidazole, DCM; bPd/C, HCO2NH4, MeOH; cAllocCl, NaH...
Scheme 18: Synthesis of pyrrolidones by homoconjugate addition.
Scheme 19: Homoconjugate addition on the fully functionalized substrate.
Scheme 20: Introduction of the olefin.
Scheme 21: Retrosynthesis of N–C9a, N–C3 bond formation.
Scheme 22: Synthesis of the pyrrolo[1,2]indole 82 using N-PSP activation.aAc2O, Py; bAc2O, Hg(OAc)2, AcOH, 90%...
Scheme 23: Synthesis of an aziridinomitosane. am-CPBA, DCM then iPr2NH, CCl4 reflux; bK2CO3, MeOH; cBnBr, KH; d...
Scheme 24: Oxidation products of a leucoaziridinomitosane obtained from a Polonovski oxidation.
Scheme 25: Polonovski oxidation of an aziridinomitosane. am-CPBA; bPd/C, H2; cDimethoxypropane, PPTS.
Scheme 26: The C1–C9a disconnection.
Scheme 27: Ziegler synthesis of desmethoxymitomycin A.aIm2C=O, THF; bNH3; cTMSOTf, 2,6-di-tert-butylpyridine, ...
Scheme 28: Transformation of sodium erythorbate.aTBDMSCl; bNaN3; cPPh3; d(Boc)2O, DMAP; eTBAF; fTf2O, Pyr.
Scheme 29: Formation of C9,C10-unsaturation in the mitomycins. am-CPBA, DCM; bO3, MeOH; cMe2S; dKHMDS, (EtO)3P...
Scheme 30: Fragmentation mechanism.
Scheme 31: Michael addition-cyclisation.
Scheme 32: SmI2 8-endo-dig cyclisation.
Scheme 33: Synthesis of pyrrolo[1,2-a]indole by 5-exo-dig radical cyclization.
Scheme 34: The C9–C9a disconnection.
Scheme 35: Intramolecular nitrile oxide cycloaddition.
Scheme 36: Regioselectivity of the INOC.
Scheme 37: Fukuyama’s INOC strategy.
Scheme 38: Synthesis of a mitosane core by rearrangement of a 1-(1-pyrrolidinyl)-1,3-butadiene.
Scheme 39: Sulikowski synthesis of an aziridinomitosene. aPd(Tol3P)2Cl2, Bu3SnF, 140; bH2, Pd/C; cTFAA, Et3N; d...
Scheme 40: Enantioselective carbene insertion.
Scheme 41: Parson’s radical cyclization.
Scheme 42: Cha’s mitomycin B core synthesis.
Scheme 43: The N-aromatic disconnection.
Scheme 44: Kishi retrosynthesis.
Scheme 45: Kishi synthesis of a starting material. aallyl bromide, K2CO3, acetone, reflux; bN,N-Dimethylanilin...
Scheme 46: Kishi synthesis of MMC 7. aLDA, THF, −78 °C then PhSeBr, THF, −78 °C; bH2O2, THF-EtOAc; cDIBAL, DCM...
Scheme 47: Acid catalyzed degradation of MMC 7.
Scheme 48: In vivo formation of apomitomycin B.
Scheme 49: Advanced intermediate for apomitomycin B synthesis.
Scheme 50: Remers synthesis of a functionalized mitosene. aTMSCl, Et3N, ZnCl2 then NBS; bAcOK; cNH2OH; dPd/C, H...
Scheme 51: Coleman synthesis of desmethoxymitomycin A. aSnCl2, PhSH, Et3N, CH3CN; bClCO2Bn, Et3N; cPPh3, DIAD,...
Scheme 52: Transition state and pyrrolidine synthesis.
Scheme 53: Air oxidation of mitosanes and aziridinomitosanes.
Scheme 54: The C9-aromatic disconnection.
Scheme 55: Synthesis of the aziridine precursor. aLHMDS, THF; bNaOH; c(s)-α-Me-BnNH2, DCC, HOBT; dDIBAL; eK2CO3...
Scheme 56: Synthesis of 206 via enamine conjugate addition.
Scheme 57: Rapoport synthesis of an aziridinomitosene.
Scheme 58: One pot synthesis of a mitomycin analog.
Scheme 59: Synthesis of compound 218 via intramolecular Heck coupling. aEtMgCl, THF, then 220; bMsCl, Et3N; cN...
Scheme 60: Elaboration of indole 223. aEt3N, Ac2O; bAcOH; cSOCl2, Et3N; dNaN3, DMF; eH2SO4, THF; fK2CO3, MeOH; ...
Scheme 61: C9-C9a functionalization from indole.
Scheme 62: Synthesis of mitomycin K. a2 equiv. MoO5.HMPA, MeOH; bPPh3, Et3N, THF-H2O; cMeOTf, Py, DCM; dMe3SiCH...
Scheme 63: Configurational stability of mitomycin K derivatives.
Scheme 64: Epimerization of carbon C9a in compound 227b.
Scheme 65: Corey–Chaykovsky synthesis of indol 235.
Scheme 66: Cory intramolecular aza-Darzens reaction for the formation of aziridinomitosene 239.
Scheme 67: Jimenez synthesis of aziridinomitosene 242.
Scheme 68: Von Braun opening of indoline 244.
Scheme 69: C9a oxidation of an aziridinomitosane with DDQ/OsO4.
Scheme 70: Synthesis of epi-mitomycin K. aNaH, Me2SO4; bH2, Pd/C; cMitscher reagent [165]; d[(trimethylsilyl)methyl...
Scheme 71: Mitomycins rearrangement.
Scheme 72: Fukuyama’s retrosynthesis.
Scheme 73: [2+3] Cycloaddition en route to isomitomycin A. aToluene, 110 °C; bDIBAL, THF, −78 °C; cAc2O, Py.; d...
Scheme 74: Final steps of Fukuyama’s synthesis.
Scheme 75: “Crisscross annulation”.
Scheme 76: Synthesis of 274; the 8-membered ring 274 was made using a crisscross annulation. a20% Pd(OH)2/C, H2...
Scheme 77: Conformational analysis of compound 273 and 275.
Scheme 78: Synthesis of a mitomycin analog. aNa2S2O4, H2O, DCM; bBnBr (10 equiv), K2CO3, 18-crown-6 (cat.), TH...
Scheme 79: Vedejs retrosynthesis.
Scheme 80: Formation of the azomethine ylide.
Scheme 81: Vedejs second synthesis of an aziridinomitosene. aDIBAL; bTPAP, NMO; c287; dTBSCl, imidazole.
Scheme 82: Trityl deprotection and new aziridine protecting group 300.
Scheme 83: Ene reaction towards benzazocinones.
Scheme 84: Benzazocenols via homo-Brook rearrangement.
Scheme 85: Pt-catalyzed [3+2] cycloaddition.
Scheme 86: Carbonylative lactamization entry to benzazocenols. aZn(OTf)2, (+)-N-methylephedrine, Et3N, TMS-ace...
Scheme 87: 8 membered ring formation by RCM. aBOC2O, NaHCO3; bTBSCl, Imidazole, DMF; callyl bromide, NaH, DMF; ...
Scheme 88: Aziridinomitosene synthesis. aTMSN3; bTFA; cPOCl3, DMF; dNaClO2, NaH2PO4, 2-methyl-2-butene; eMeI, ...
Scheme 89: Metathesis from an indole.
Scheme 90: Synthesis of early biosynthetic intermediates of mitomycins.
Diels- Alder reactions using 4,7-dioxygenated indanones as dienophiles for regioselective construction of oxygenated 2,3-dihydrobenz[f]indenone skeleton
- Natsuno Etomi,
- Takuya Kumamoto,
- Waka Nakanishi and
- Tsutomu Ishikawa
Beilstein J. Org. Chem. 2008, 4, No. 15, doi:10.3762/bjoc.4.15
- B; quinone route) [28]; 2) regioselective ring-opening of 5,8-epoxy-2,3-dihydrobenz[f]indenone 11 derived from benzyne 10 and furan (9) (path C, benzyne route). Now we report that both of the methods are effective for the construction of the 2,3-dihydrobenz[f]indenone skeleton, but not for the
- regioselective synthesis of the desired 4,8,9-trioxygenated ones. Results and Discussion In the quinone route, we designed several indanetriones to modulate steric and electronic factors; i.e. 1,4,7-indanetrione 8, the 6-brominated quinone 12, and the corresponding 4-monoacetals 13 and 14 (Scheme 2
- regioselectivity was not affected in the reaction in the presence of a catalytic amount of BF3 · OEt2 (entry 7). We next turned to the use of quinone monoacetals 13 and 14 as dienophiles [36]. No adduct was formed on reaction of 13 in CH2Cl2 without a catalyst at room temperature (rt) (entry 8), whereas refluxing
Graphical Abstract
Figure 1: The structure of kinamycins.
Scheme 1: Retrosynthesis of kinamycins.
Scheme 2: Synthesis of quinones 8 and 12 and the acetals 13 and 14. Reagents and conditions: a) P2O5, CH3SO3H...
Figure 2: Selected HMBC correlations (lines) and NOE enhancements (dash) on 21 (a) and on 22 (b).
Scheme 3: DAR of benzyne 10 and furan (9). Reagents and conditions: a) ethylene glycol, PPTS, benzene, reflux...
Figure 3: Selected HMBC correlations (a) and NOE enhancements (b) on the ring-opened product 27.
Figure 4: Transition states supposed for the regioselective DAR via quinone route.
Figure 5: Representative LUMO coeffients of quinones 8 and 12 (a) and their reaction courses with diene 7 (b)....
Scheme 4: The proposed mechanism for the acid-induced ring opening of epoxynaphthalene 29 by Giles et al. [19].
Scheme 5: Supposed reaction pathways for the acid-induced ring opening of 11.
Variations in product in reactions of naphthoquinone with primary amines
- Marjit W. Singh,
- Anirban Karmakar,
- Nilotpal Barooah and
- Jubaraj B. Baruah
Beilstein J. Org. Chem. 2007, 3, No. 10, doi:10.1186/1860-5397-3-10
- have anion binding ability on protonation or have complex forming ability with metals. The incorporation of pyridine ring to a quinone has also another facet as we have recently observed that in picolyl derivative of 1,8-naphthalimides the π-π interactions are governed by the position of the nitrogen
Graphical Abstract
Scheme 1: Reaction of 1,2-naphthoquinone with primary amines.
Figure 1: The solid state structure of (a) 1 and (b) 2 (drawn with 20% thermal ellipsoids).
Scheme 2: Equivalence of reactivity between 1,2 and 1,4-naphthoquinone.
Scheme 3: The reaction of picolylamine with 1,4-naphthoquinone.
Figure 2: (a) The crystal structure of 3 and (b) weak interactions in 3 leading to self-assembly, (c) Structu...
Scheme 4: The reaction of 1,4-naphthoquinone with 4-aminothiophenol and 4-aminophenol.
Figure 3: The 1HNMR spectra (400 MHz) of the reaction mixture of 1,4-naphthoquinone with 4-amino thiophenol (...
Figure 4: The structure of the products from the reaction of 1,4-naphthoquinone with (a) 4-aminothiophenol (b...
Effect of transannular interaction on the redox- potentials in a series of bicyclic quinones
- Grigoriy Sereda,
- Jesse Van Heukelom,
- Miles Koppang,
- Sudha Ramreddy and
- Nicole Collins
Beilstein J. Org. Chem. 2006, 2, No. 26, doi:10.1186/1860-5397-2-26
- the triptycene-quinone system selectively destabilize the product of the two-electron reduction. Conclusion We have shown that first redox-potentials of substituted bicyclic quinones correlate with their calculated LUMO energies and the energies of reduction. The second redox-potentials correlate with
- calculated LUMO+1 energies. As opposed to the LUMO orbitals, the LUMO+1 orbital coefficients are weighted significantly on the non-quinone part of the bicyclic system. This accounts for: (1) significantly larger substituent effect on the second redox-potentials, than on the first redox-potentials; (2) lack
- of stability of the product of two electron reduction of 5,8-diacetoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione 5. Background It has been shown that 9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione (triptycene-quinone, 1) exhibits anti-leukemia activity, comparable with activity of
Graphical Abstract
Figure 1: Bicyclic quinones explored for the transannular interaction.
Figure 2: Conformation A of compound 2.
Figure 3: Conformation B of compound 2.
Figure 4: First formal redox-potentials of compounds 1–5 vs. their calculated LUMO energies.
Figure 5: First formal redox-potentials of compounds 1–5 vs. their calculated energies of reduction.
Figure 6: Second formal redox-potentials of compounds 1–5 vs. their calculated LUMO+1 energies.
Figure 7: LUMO of Compound 1.
Figure 8: LUMO+1 of Compound 1.
Figure 9: LUMO of Compound 2.
Figure 10: LUMO+1 of Compound 2.
Figure 11: LUMO of Compound 4.
Figure 12: LUMO+1 of Compound 4.
Figure 13: LUMO of Compound 5.
Figure 14: LUMO+1 of Compound 5.
Figure 15: LUMO of the reduced species 5·−.
Figure 16: CV for p-benzoquinone and quinone 3.
Total syntheses of oxygenated brazanquinones via regioselective homologous anionic Fries rearrangement of benzylic O-carbamates
- Glaucia Barbosa Candido Alves Slana,
- Mariângela Soares de Azevedo,
- Rosângela Sabattini Capella Lopes,
- Cláudio Cerqueira Lopes and
- Jari Nobrega Cardoso
Beilstein J. Org. Chem. 2006, 2, No. 1, doi:10.1186/1860-5397-2-1
- condensed aromatics. We found this route very attractive and envisaged that by in situ treatment of intermediate 4 with the third equivalent of sec-BuLi, the cyclization to the desired quinone 1a-d would be obtained. One unexpected result was the formation of the phthalide 9 when the dimethoxy carbamate 2d
Graphical Abstract
Figure 1: Examples of carbanionic aromatic chemistry rearrangements.
Scheme 1: Retrosyntheses of Brazanquinones (1).
Scheme 2: Total syntheses of brazanquinones (1 a-c).
Scheme 3: Total syntheses of phthalide (9).
