- Allyl 4-Chlorophenyl Sulfone as a Versatile 1,1-Synthon for Sequential α-Alkylation/Cobalt-Catalyzed Allylic Substitution
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Despite their unique potential as rare 1,1-dipole synthons, allyl sulfones are rarely used in target-oriented syntheses, likely due to the lack of a general catalytic method for their branch-selective allylic substitution. Herein, we identified allyl 4-chlorophenyl sulfone as a versatile linchpin for both base-mediated α-derivatization and subsequent cobalt-catalyzed allylic substitution. The sequential transformations allow for highly regioselective access to branched allylic substitution products with a variety of aliphatic side chains. The photoredox-enabled cobalt catalysis is indispensable for achieving high yields and regioselectivity for the desulfonylative substitution in contrast to traditional metal-catalyzed protocols, which lead to inferior outcomes in the corresponding transformations.
- Kojima, Masahiro,Matsunaga, Shigeki
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p. 1934 - 1946
(2020/07/03)
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- Probing the binding pocket of the active site of aromatase with 2-phenylaliphatic androsta-1,4-diene-3,17-dione steroids
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A series of 2-phenylaliphatic-substituted androsta-1,4-diene-3,17-diones (6) as well as their androstenedione derivatives (5) were synthesized as aromatase inhibitors to gain insights of structure-activity relationships of varying the alkyl moiety (C1 to C4) of the 2-phenylaliphatic substituents as well as introducing a methyl- or trifluoromethyl function to p-position of a phenethyl moiety to the inhibitory activity. The inhibitors examined showed a competitive type inhibition. The 2-phenpropylandrosta-1,4-diene 6c was the most powerful inhibitor (Ki: 16.1 nM) among them. Compounds 6c along with the phenethyl derivative 6b caused a time-dependent inactivation of aromatase (kinact: 0.0293 and 0.0454 min-1 for 6b and 6c, respectively). The inactivation was prevented by the substrate androstenedione, and no significant effect of l-cysteine on the inactivation was observed in each case. Molecular docking of the phenpropyl compound 6c to aromatase was conducted to demonstrate that the phenpropyl group orients to a hydrophobic binding pocket in the active site to result in the formation of thermodynamically stable enzyme-inhibitor complex.
- Takahashi, Madoka,Yamashita, Kouwa,Numazawa, Mitsuteru
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experimental part
p. 330 - 337
(2010/04/29)
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- Design and synthesis of phenethyl benzo[1,4]oxazine-3-ones as potent inhibitors of PI3Kinaseγ
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The Type 1 PI3Kinases comprise a family of enzymes, which primarily phosphorylate PIP2 to give the second messenger PIP3, a key player in many intracellular signaling processes [Science, 2002, 296, 1655; Trends Pharmacol. Sci. 2003, 24, 366]. Of the four type 1 PI3Ks, the γ-isoform, which is expressed almost exclusively in leukocytes [Curr. Biol., 1997, 7, R470], is of particular interest with respect to its role in inflammatory diseases such as rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) [Mol. Med. Today, 2000, 6, 347]. Investigation of a series of 4,6-disubstituted-4H-benzo[1,4]oxazin-3-ones has led to the identification of single-digit nanomolar inhibitors of PI3Kγ, several of which had good cell based activity and were shown to be active in vivo in an aspectic peritonitis model of inflammatory cell migration.
- Lanni Jr., Thomas B.,Greene, Keri L.,Kolz, Christine N.,Para, Kimberly S.,Visnick, Melean,Mobley, James L.,Dudley, David T.,Baginski, Theodore J.,Liimatta, Marya B.
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p. 756 - 760
(2007/10/03)
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- ARTEMISININ-BASED PEROXIDE COMPOUNDS AS BROAD SPECTRUM ANTI-INFECTIVE AGENTS
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Described herein is the synthesis, bioassay results and utility of new C-9 and C-10 substituted artemisinin derivatives with easily functionalizable groups attached to the artemisinin skeleton through carbon chain or heteroatoms. Described also is the demonstration of this class of compounds for their broad-spectrum anti-parasitic activity. Certain of these analogs possess noticeable cytotoxicity deliberately focused on treatment of cancerous diseases.
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Page/Page column 47-48
(2010/02/07)
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- Structure-activity relationships of the antimalarial agent artemisinin. 7. Direct modification of (+)-artemisinin and in vivo antimalarial screening of new, potential preclinical antimalarial candidates
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On the basis of earlier reported quantitative structure-activity relationship studies, a series of 9β-16-(arylalkyl)-10-deoxoartemisinins were proposed for synthesis. Several of the new compounds 7 and 10-14 were synthesized employing the key synthetic intermediate 23. In a second approach, the natural product (+)-artemisinic acid was utilized as an acceptor for conjugate addition, and the resultant homologated acids were subjected to singlet oxygenation and acid treatment to provide artemisinin analogues. Under a new approach, we developed a one step reaction for the interconversion of artemisinin 1 into artemisitene 22 that did not employ selenium-based reagents and found that 2-arylethyliodides would undergo facile radical-induced conjugate addition to the exomethylene lactone of 22 in good yield. The lactone carbonyls were removed sequentially by diisobutylaluminum hydride reduction followed directly by a second reduction (BF3-etherate/Et3SiH) to afford the desired corresponding pyrans. Six additional halogen-substituted aromatic side chains were installed via 22 furnishing the bioassay candidates 15-20. The analogues were examined for in vitro antimalarial activity in the W-2 and D-6 clones of Plasmodium falciparum and were additionally tested in vivo in Plasmodium berghei- and/or Plasmodium yoelii-infected mice. Several of the compounds emerged as highly potent orally active candidates without obvious toxicity. Of these, two were chosen for pharmacokinetic evaluation, 14 and 17.
- Avery, Mitchell A.,Alvim-Gaston, Maria,Vroman, Jeffrey A.,Wu, Baogen,Ager, Arba,Peters, Wallace,Robinson, Brian L.,Charman, William
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p. 4321 - 4335
(2007/10/03)
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- 2-substituted (2SR)-2-amino-2-((1SR,2SR)-2-carboxycycloprop-1- yl)glycines as potent and selective antagonists of group II metabotropic glutamate receptors. 2. Effects of aromatic substitution, pharmacological characterization, and bioavailability
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In this paper we describe the synthesis of a series of α-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxycyclopropylglycine (2, L-CCG 1). Incorporation of a substituent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a series of four isomers, i.e., two racemic diastereomers. On the basis of the improvement in affinity realized for the α-phenylethyl analogue 3, in this paper we explored the effects of substitution on the aromatic ring as a strategy to increase the affinity of these compounds for group II mGluRs. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1- aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. Meta substitution on the aromatic ring of 3 with a variety of substituents, both electron donating (e.g., methyl, hydroxy, amino, methoxy, phenyl, phenoxy) and electron withdrawing (e.g., fluorine, chlorine, bromine, carboxy, trifluoromethyl) gave from 1.5- to 4.5-fold increases in affinity. Substitution with p-fluorine, as in 97 (IC50 = 0.022 ± 0.002), was the exception. Here, a greater increase in affinity was realized than for either the ortho- or meta-substituted analogues; 97 was the most potent compound resulting from monosubstitution of the aromatic. At best, only modest increases in affinity were realized for certain compounds bearing either two chlorines or two fluorines, and two methoxy groups gave no improvement in affinity (all examined in a variety of substitution patterns). Three amino acids, 4, 5, and 104, were resolved into their four constituent isomers, and affinity and functional activity for group II mGluRs was found to reside solely in the S,S,S-isomers of each, consistent with 1. With an IC50 = 2.9 ± 0.6 nM, the resolved xanthylmethyl compound 168 was the most potent compound from this SAR. Amino acid 168 demonstrated high plasma levels following intraperitoneal (ip) administration and readily penetrated into the brain. This compound, however, had only limited (~5%) oral bioavailability. Systemic administration of 168 protected mice from limbic seizures produced by the mGluR agonist 3,5-dihydroxyphenylglycine, with an ED50 = 31 mg/kg (ip, 60 min preinjection). Thus, 168 represents a valuable tool to study the role of group II mGluRs in disease.
- Ornstein, Paul L.,Bleisch, Thomas J.,Arnold, M. Brian,Kennedy, Joseph H.,Wright, Rebecca A.,Johnson, Bryan G.,Tizzano, Joseph P.,Helton, David R.,Kallman, Mary Jeanne,Schoepp, Darryle D.,Hérin, Marc
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p. 358 - 378
(2007/10/03)
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