- Pd-Catalyzed Nazarov-Type Cyclization: Application in the Total Synthesis of β-Diasarone and Other Complex Cyclopentanoids
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We describe the palladium-catalyzed Nazarov-type cyclization of easily accessible (hetero)arylallyl acetates to pentannulated (hetero)arenes. This method provides ready access to various types of bi-, tri-, tetra-, and pentacyclic cyclopentanoids under ne
- Singh, Bara,Bankar, Siddheshwar K.,Ramasastry
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supporting information
p. 1043 - 1048
(2022/02/05)
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- Dihydrochelerythrine and its derivatives: Synthesis and their application as potential G-quadruplex DNA stabilizing agents
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A convenient route was envisaged toward the synthesis of dihydrochelerythrine (DHCHL), 4 by intramolecular Suzuki coupling of 2-bromo-N-(2-bromobenzyl)-naphthalen-1-amine derivative 5 via in situ generated arylborane. This compound was converted to (±)-6-acetonyldihydrochelerythrine (ADC), 3 which was then resolved by chiral prep-HPLC. Efficiency of DHCHL for the stabilization of promoter quadruplex DNA structures and a comparison study with the parent natural alkaloid chelerythrine (CHL), 1 was performed. A thorough investigation was carried out to assess the quadruplex binding affinity by using various biophysical and biochemical studies and the binding mode was explained by using molecular modeling and dynamics studies. Results clearly indicate that DHCHL is a strong G-quadruplex stabilizer with affinity similar to that of the parent alkaloid CHL. Compounds ADC and DHCHL were also screened against different human cancer cell lines. Among the cancer cells, (±)-ADC and its enantiomers showed varied (15-48%) inhibition against human colorectal cell line HCT116 and breast cancer cell line MDA-MB-231 albeit low enantio-specificity in the inhibitory effect; whereas DHCHL showed 30% inhibition against A431 cell line only, suggesting the compounds are indeed cancer tissue specific.
- Malhotra, Rajesh,Rarhi, Chhanda,Diveshkumar,Barik, Rajib,D'Cunha, Ruhee,Dhar, Pranab,Kundu, Mrinalkanti,Chattopadhyay, Subrata,Roy, Subho,Basu, Sourav,Pradeepkumar,Hajra, Saumen
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p. 2887 - 2896
(2016/06/13)
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- Transition metals in organic synthesis, part 96. First total synthesis of streptoverticillin: Unambiguous confirmation of the absolute configuration
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Using an iron-mediated construction of the carbazole framework, the first synthesis of streptoverticillin is described and the absolute configuration of the natural product is confirmed. The synthesis exploits a novel oxygen-mediated aromatization of tric
- Thomas, Claudia,Kataeva, Olga,Kn?lker, Hans-Joachim
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scheme or table
p. 2663 - 2666
(2011/12/04)
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- NOVEL INHIBITORS OF BETA-LACTAMASE
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This invention provides novel β-lactamase inhibitors of the aryl- and heteroarylsulfonamidomethylphosphonate monoester class having nitrogen-based cations or quarternary ammonium groups. The compounds inhibit three classes of β-lactamases and synergize the antibacterial effects of β-lactam antibiotics (e.g., imipenem and ceftazidime) against those micro-organisms normally resistant to the β-lactam antibiotics as a result of the presence of the β-lactamases. Formula (I) or pharmaceutically acceptable salt thereof.
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Page/Page column 18
(2010/12/29)
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- A direct palladium-catalyzed route to selectively substituted carbazoles through sequential C-C and C-N bond formation: Synthesis of carbazomycin A
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The present paper offers a synthetically simple one-pot procedure for the catalytic preparation of the biologically interesting class of carbazoles. The new procedure is based on the combined catalysis of palladium and norbornene starting from o-substituted iodoarenes and N-sulfonylated or N-acetylated o-bromoanilines. A well-known member of this class, carbazomycin A, has been successfully prepared.
- Della Ca', Nicola,Sassi, Giovanni,Catellani, Marta
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supporting information; experimental part
p. 2179 - 2182
(2009/10/02)
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- Transition metals in organic synthesis, part 84.1 application of iron- and nickel-mediated coupling reactions to the total synthesis of the neuronal cell protecting substance (±)-carquinostatin A
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Using iron- and nickel-mediated coupling reactions as key steps a convergent and highly efficient total synthesis of the potent neuronal cell protecting alkaloid (±)-carquinostatin A has been accomplished.
- Fr?hner, Wolfgang,Reddy, Kethiri R.,Kn?lker, Hans-Joachim
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p. 895 - 912
(2008/09/18)
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- NOVEL SULFONAMIDOMETHYLPHOSPHONATE INHIBITORS OF BETA-LACTAMASE
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This invention provides novel β-lactamase inhibitors of the aryl-and heteroaryl-sulfonamidomethylphosphonate monoester class. The compounds inhibit three classes of β-lactamases and synergize the antibacterial effects of β-lactam antibiotics (e.g., imipenem and ceftazimdime) against those micro-organisms normally resistant to the β-lactam antibiotics as a result of the presence of the β-lactamases. Formula (I) or a pro-drug or pharmaceutically acceptable salt thereof, wherein: W represents: Formula (II).
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Page/Page column 24
(2008/06/13)
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- PROCESSES OF MAKING SESQUITERPENOID TASHIRONIN, ITS ANALOGS AND THEIR USES
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The compound having the structure of the formula (genus of compound 1 excluding Tashironin or Debenzoyltashironin) wherein, R1 is H or Bz when no more than three of R8, R9, R10 and R11 are H, or R1 is Bn, (C1-C4) alkyl, or CF3; R2 is H, (C1-C4) aldyl, halide, OC(O) (C1-C4) alkyl, OC(O) Ph, or OCF3; R3 is p-toluene sulfonyloxy, methane sulfonyloxy, C(O) (C1-C4)alkyl, or OC(O) (C1-C4)alkyl, bond α is a single bond, and bond β is a double bond or R3 is O, bond α is a double bond and bond β is a single bond; R4 is H, I, Br, Cl, Si(CH3)3, (C1-C4)alkyl, or OCF3; R5 is OH, OSi (CH3)3, O(C1-C4)alkyl, or OCF3, and bond γ is a single bond, or R5 is O and bond γ is a double bond; R6 is H, (C1-C4) alkyl, or CF3.
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- A practical synthesis of 3,4-dimethoxy-o-toluic acid
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A streamlined, telescoped process has been developed for the preparation of 3,4-dimethoxy-o-toluic acid, starting with economical and readily available 2,3-dimethoxybenzaldehyde. Catalytic reduction of the aldehyde functional group generated dimethoxytolu
- Connolly, Terrence J.,Matchett, Michael,McGarry, Patrick,Sukhtankar, Sunil,Zhu, Jiang
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p. 624 - 627
(2013/09/02)
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- Transition metal complexes in organic synthesis. Part 58: First enantioselective total synthesis of the potent neuronal cell protecting substance carquinostatin a from (R)-propene oxide
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Starting from enantiopure (R)-propene oxide the first enantioselective total synthesis of the potent neuronal cell protecting alkaloid carquinostatin A has been accomplished by using iron- and nickel-mediated coupling reactions. (C) 2000 Elsevier Science
- Kn?lker, Hans-Joachim,Baum, Elke,Reddy, Kethiri R.
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p. 1171 - 1174
(2007/10/03)
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- Transition metal complexes in organic synthesis, part 54.1 Improved total syntheses of the antibiotic alkaloids carbazomycin A and B
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Considerably improved total syntheses of the carbazole antibiotics carbazomycin A and B are reported using a convergent iron-mediated one-pot construction of the carbazole framework by oxidative cyclization in the air.
- Knoelker, Hans-Joachim,Froehner, Wolfgang
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p. 6915 - 6918
(2007/10/03)
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- A convenient procedure for the synthesis of 1-tetralone dertivatives using a Suzuki coupling-Friedel-Crafts acylation sequence
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The reported 1-tetralone derivatives have been synthesized from arylbromides using as keys steps a Suzuki coupling followed by intramolecular Friedel-Crafts acylation.
- Esteban, Gemma,Lopez-Sanchez, Miguel A.,Martinez, Ma. Eugenia,Plumet, Joaquin
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p. 197 - 212
(2007/10/03)
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- Transition metal complexes in organic synthesis, Part 37. Convergent iron-mediated total synthesis of the potent lipid peroxidation inhibitor carbazoquinocin C
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The antioxidative agent carbazoquinocin C has been synthesized by a convergent iron-mediated construction of the carbazole nucleus using a novel one-pot C-C and C-N bond formation which is carried out in the air.
- Knoelker, Hans-Joachim,Froehner, Wolfgang
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p. 1535 - 1538
(2007/10/03)
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- Transition Metal Complexes in Organic Synthesis, Part 39. First Total Synthesis of the Potent Neuronal Cell Protecting Substance (±)-Carquinostatin a via Iron- and Nickel-Mediated Coupling Reactions
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The first total synthesis of the potent neuronal cell protecting carbazole alkaloid (±)-carquinostatin A was achieved by using an iron-mediated construction of the carbazole framework and a regioselective nickel-mediated prenylation as the key-steps.
- Kn?lker, Hans-Joachim,Fr?hner, Wolfgang
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p. 1108 - 1110
(2007/10/03)
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- Synthesis of linear oligo(catechol) ligands for the metal directed self-assembling of helicates
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The synthesis of the oligo(catechol) systems 1-4 with different substituents, length of the connecting spacer, and number of catechol units is achieved by the use of various coupling reactions (e.g. Wurtz, Glaser-Eglinton, Stephens-Castro). In order to do this methods of preparing the building blocks, 2,3-dimethoxybenzyl bromides 5, 2,3-dimethoxyphenylacetylene (17), or 1,4-dibromo-2,3-dimethoxybenzene (23) have been developed starting with simple catechol (benzene-1,2-diol) derivatives.
- Albrecht, Markus
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p. 230 - 236
(2007/10/03)
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- Thallium in Organic Synthesis. 58. Regiospecific Intermolecular Oxidative Dehydrodimerization of Aromatic Compounds to Biaryls Using Thallium (III) Trifluoroacetate
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Treatment of a variety of aromatic substrates with thallium(III) trifluoroacetate (TTFA) in trifluoroacetic acid (TFA), or in carbon tetrachloride or acetonitrile containing boron trifluoride etherate, results in smooth, rapid, and direct regiospecific oxidative dehydrodimerization to give symmetrical biaryls in good to excellent yield.The method is particularly useful when applied to substrates in which the ring substituents are either electron donating or mildly electron withdrawing.Aromatic substrates which contain powerful electron-withdrawing groups (CN, COOR, NO2) fail to react.The reaction is postulated to proceed via (a) reaction of TTFA with the aromatic substrate and generation of the radical cation Ar+; (b) reaction of this electrophile with the aromatic substrate; (c) oxidative aromatization of the intermediate thus produced by TTFA.Biaryls can be obtained similarly by oxidation of the same substrates with either mercury(II) trifluoroacetate in TFA containing boron trifluoride, lead(IV) acetate in acetonitrile containing boron trifluoride, iron(III) chloride in methylene chloride, or cobalt(III) fluoride in TFA.Yields in the Hg(II) and Fe(III) reactions are generally inferior to those obtained with TTFA, but those obtained in the Pb(IV) and Co(III) oxidations are in many instances comparable to, or even better than, the TTFA results.The oxidations with Hg(II), Pb(IV), Fe(III), and CO(III) are also postulated to proceed via a radical cation mechanism.
- McKillop, Alexander,Turrell, Andrew G.,Young, Derek W.,Taylor, Edward C.
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p. 6504 - 6512
(2007/10/02)
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