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  • Articles  (6,186)
  • Organic Chemistry  (5,482)
  • Rats  (704)
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  • 1980-1984  (4,110)
  • 1950-1954  (2,076)
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  • Articles  (6,186)
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  • 101
    Publication Date: 1984-11-16
    Description: In rats ischemia of the forebrain induced by a 30-minute occlusion of the carotid artery, followed by 120 minutes of arterial reperfusion, produced ischemic lesions of selectively vulnerable pyramidal cells in both hippocampi. Focal microinfusion into the dorsal hippocampus of 2-amino-7-phosphonoheptanoic acid, an antagonist of excitation at the N-methyl-D-aspartate-preferring receptor, before ischemia was induced protected against the development of ischemic damage. It is proposed that excitatory neurotransmission plays an important role in selective neuronal loss due to cerebral ischemia.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Simon, R P -- Swan, J H -- Griffiths, T -- Meldrum, B S -- 5 K07 NS00437-04/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1984 Nov 16;226(4676):850-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6093256" target="_blank"〉PubMed〈/a〉
    Keywords: *2-Amino-5-phosphonovalerate/*analogs & derivatives ; Amino Acids/pharmacology ; Animals ; Brain Ischemia/pathology/*prevention & control ; Hippocampus/drug effects/pathology ; Rats ; Receptors, N-Methyl-D-Aspartate ; Receptors, Neurotransmitter/drug effects/*physiology ; Synaptic Transmission/drug effects
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  • 102
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-04-06
    Description: Biochemical investigation of receptors for neurotransmitters and drugs in the brain has been one of the most active areas of molecular neuroscience during the past decade. This work has permitted fundamental insights into how binding of neurotransmitters to their receptors excites or inhibits neuronal firing or changes cellular metabolism. The recognition of receptor subtypes has suggested subtle ways for neurotransmitters to modulate neuronal functioning. Finally, the ability to measure receptor sites in simple test tube systems and to distinguish readily between agonists and antagonists has provided useful probes for drug discovery programs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Snyder, S H -- DA-00266/DA/NIDA NIH HHS/ -- MH-18501/MH/NIMH NIH HHS/ -- NS-16375/NS/NINDS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1984 Apr 6;224(4644):22-31.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6322304" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/*metabolism/physiology ; Brain Chemistry ; Calcium Channel Blockers/metabolism ; Cerebellum/metabolism ; Humans ; Rabbits ; Rats ; Receptors, Adrenergic/metabolism ; Receptors, Catecholamine ; Receptors, Cell Surface/metabolism ; Receptors, Dopamine/metabolism ; Receptors, Drug/analysis/*metabolism/physiology ; Receptors, GABA-A ; Receptors, Neurotransmitter/analysis/*metabolism/physiology ; Receptors, Opioid/metabolism ; Receptors, Purinergic ; Receptors, Serotonin/metabolism
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  • 103
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-10-12
    Description: Rhodopsin kinase, an enzyme involved in photochemical transduction in the retina, has been found in the mammalian pineal gland in amounts equal to those in the retina; other tissues had 7 percent of this amount, or less. This finding suggests that, in mammals, rhodopsin kinase functions in the pineal gland and other tissues to phosphorylate rhodopsin-like integral membrane receptors and is thereby involved in signal transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Somers, R L -- Klein, D C -- New York, N.Y. -- Science. 1984 Oct 12;226(4671):182-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6091271" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain/enzymology ; *Eye Proteins ; G-Protein-Coupled Receptor Kinase 1 ; Light ; Lung/enzymology ; Phosphorylation ; Pineal Gland/*enzymology ; Pituitary Gland/enzymology ; Protein Kinase Inhibitors ; Protein Kinases/*metabolism ; Rats ; Receptors, Adrenergic, beta/metabolism ; Retina/enzymology ; Tissue Distribution ; Zinc/pharmacology
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  • 104
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-04-06
    Description: Indirect immunofluorescence was used to show the presence of galactocerebroside (galC), a lipid found in myelin, on the surface of about half of the Schwann cells isolated from neonatal rat sciatic nerves and cultured for 1 day without neurons. By day 4 in vitro, the Schwann cells had all lost their surface galC. Three days after beginning treatment with 10(-3) molar 8-bromo-adenosine 3',5'-monophosphate (8-bromo cyclic AMP) or N6,O2'-dibutyryl adenosine 3',5'-monophosphate (dibutyryl cyclic AMP), galC reappeared on the Schwann cells, and 2 days later 48 percent of the cultured Schwann cells showed surface galC. Tritium from tritiated D-galactose was incorporated into galC by the 8-bromo cyclic AMP-and dibutyryl cyclic AMP-treated cultures at a rate 15 times the control rate.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sobue, G -- Pleasure, D -- HD08536/HD/NICHD NIH HHS/ -- NS08075/NS/NINDS NIH HHS/ -- NS11037/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1984 Apr 6;224(4644):72-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6322307" target="_blank"〉PubMed〈/a〉
    Keywords: 8-Bromo Cyclic Adenosine Monophosphate/pharmacology ; Adenosine Monophosphate/*analogs & derivatives ; Animals ; Bucladesine/pharmacology ; Butyrates/pharmacology ; Butyric Acid ; Cells, Cultured ; Cerebrosides/*metabolism ; Fluorescent Antibody Technique ; Galactosylceramides/*metabolism ; Myelin Sheath/metabolism ; Rats ; Schwann Cells/*drug effects/metabolism ; Sciatic Nerve/metabolism
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  • 105
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-08-17
    Description: Active and passive sensitization, both in vivo and in vitro, caused significant hyperpolarization of airway smooth muscle cell preparations isolated from guinea pigs. An increase in the contribution of the electrogenic Na+ pump to the resting membrane potential was responsible for this change. Hyperpolarization, as induced by passive sensitization, was not prevented by agents that inhibit specific mediators of anaphylaxis but was abolished when serum from sensitized animals was heated. The heat-sensitive serum factor, presumably reaginic antibodies, appears to be responsible for the membrane hyperpolarization of airway smooth muscle cells after sensitization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Souhrada, M -- Souhrada, J F -- HL-28063/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1984 Aug 17;225(4663):723-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6087455" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Membrane/*immunology ; Immunization ; Immunization, Passive ; Ion Channels/immunology ; Male ; Mast Cells/immunology ; Membrane Potentials ; Mice ; Muscle, Smooth/*immunology ; Rabbits ; Rats ; Respiratory System/*immunology ; Sodium/metabolism ; Trachea/immunology
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  • 106
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-09-21
    Description: Some 30,000 genes are expressed exclusively in the rat brain, many of which contain a genetic element called an identifier sequence located in at least one of their introns. The identifier sequences are transcribed by RNA polymerase III exclusively in neurons to produce two RNA species, BC1 and BC2, of 160 and 100 to 110 nucleotides. This transcriptional event may define regions of chromatin that contain neuronal-specific genes and may poise these genes for transcription by polymerase II by rendering the gene promoters accessible to soluble trans-acting molecules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sutcliffe, J G -- Milner, R J -- Gottesfeld, J M -- Reynolds, W -- GM32355/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1984 Sep 21;225(4668):1308-15.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6474179" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Brain/*metabolism ; Brain Stem/metabolism ; Cerebral Cortex/metabolism ; *Genes ; Neurons/*metabolism ; Nucleic Acid Conformation ; Operon ; Phenotype ; RNA Polymerase III/metabolism ; RNA, Messenger/genetics ; Rats ; Spinal Cord/metabolism ; Transcription, Genetic
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  • 107
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-10-26
    Description: Intracerebroventricular administration of human pancreatic growth hormone-releasing factor caused a dose-dependent inhibition of growth hormone secretion, elevated plasma glucose concentrations, and produced marked behavioral and motor effects. Immunoneutralization with antiserum to somatostatin did not reverse the suppression of growth hormone. These findings suggest that hypothalamic growth hormone-releasing factor may regulate its own neurosecretion through an "ultrashort-loop" negative feedback mechanism and may have important neurotransmitter and neuromodulatory functions in the brain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tannenbaum, G S -- New York, N.Y. -- Science. 1984 Oct 26;226(4673):464-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6436973" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*drug effects ; *Blood Glucose ; Dose-Response Relationship, Drug ; Feedback ; Growth Hormone/*secretion ; Growth Hormone-Releasing Hormone/*pharmacology ; Male ; Rats ; Rats, Inbred Strains
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  • 108
    Publication Date: 1984-07-27
    Description: Auranofin, 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranosato-S-(triethy lphosphine)- gold(I), an experimental antiarthritis pharmaceutical, metabolized in contact with hamster or rat gut wall to yield the deacetylated form of the drug. This product, 1-thio-beta-D-glucopyranosato-S-(triethylphosphine)gold(I), passed through hamster or rat intestinal wall in an everted gut experiment. The metabolite was separated by high-performance liquid chromatography and characterized by retention time, chemical reactivity to yield a known product, and comparison to a synthetic sample of the metabolite.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tepperman, K -- Finer, R -- Donovan, S -- Elder, R C -- Doi, J -- Ratliff, D -- Ng, K -- New York, N.Y. -- Science. 1984 Jul 27;225(4660):430-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6429854" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anti-Inflammatory Agents/*metabolism ; Auranofin ; Aurothioglucose/*analogs & derivatives/metabolism ; Chromatography, High Pressure Liquid ; Cricetinae ; Gold/*analogs & derivatives ; *Intestinal Absorption ; Mesocricetus ; Rats ; Rats, Inbred Strains
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  • 109
    Publication Date: 1984-12-14
    Description: Portions of the brain stem seem normally to inhibit pain. In man and laboratory animals these brain areas and pathways from them to spinal sensory circuits can be activated by focal stimulation. Endogenous opioids appear to be implicated although separate nonopioid mechanisms are also evident. Stress seems to be a natural stimulus triggering pain suppression. Properties of electric footshock have been shown to determine the opioid or nonopioid basis of stress-induced analgesia. Two different opioid systems can be activated by different footshock paradigms. This dissection of stress analgesia has begun to integrate divergent findings concerning pain inhibition and also to account for some of the variance that has obscured the reliable measurement of the effects of stress on tumor growth and immune function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Terman, G W -- Shavit, Y -- Lewis, J W -- Cannon, J T -- Liebeskind, J C -- MH 15795/MH/NIMH NIH HHS/ -- NS-07628/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1984 Dec 14;226(4680):1270-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6505691" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological ; Adrenalectomy ; Anesthesia ; Animals ; Brain Stem/physiology ; Conditioning (Psychology) ; Electroshock ; Endorphins/physiology ; Histamine/physiology ; Humans ; Hypophysectomy ; Immunosuppression ; Naltrexone/pharmacology ; Neoplasms/physiopathology ; Nociceptors/physiology ; Pain/*physiopathology ; Pentobarbital/pharmacology ; Rats ; Stress, Physiological/*physiopathology
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  • 110
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-05-04
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tabakoff, B -- Melchior, C L -- Hoffman, P -- New York, N.Y. -- Science. 1984 May 4;224(4648):523-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6710154" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Drug Tolerance ; Ethanol/*pharmacology ; *Learning ; Rats
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  • 111
    Publication Date: 1984-02-17
    Description: Ribose is cardioprotective in the rat in a variety of pathophysiological conditions. The metabolic basis for this effect is the low capacity of the oxidative pentose phosphate pathway in the myocardium. Ribose bypasses this pathway, elevates the available pool of 5-phosphoribosyl-l-pyrophosphate, and thus stimulates the biosynthesis of adenine nucleotides. In this study reported here the activity of glucose-6-phosphate dehydrogenase, the first and rate-limiting enzyme of the oxidative pentose phosphate shunt, was very low in the human heart and was of the same order of magnitude in the myocardium of various animal species. Furthermore, ribose had a similar stimulating effect on myocardial adenine nucleotide biosynthesis in the guinea pig, in which hemodynamic parameters are different from those in the rat. It is concluded that the metabolic basis for the effectiveness of ribose is similar in all species investigated.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmer, H G -- Ibel, H -- Suchner, U -- Schad, H -- New York, N.Y. -- Science. 1984 Feb 17;223(4637):712-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6420889" target="_blank"〉PubMed〈/a〉
    Keywords: Adenine Nucleotides/metabolism ; Animals ; Cattle ; Dogs ; Glucosephosphate Dehydrogenase/metabolism ; Guinea Pigs ; Haplorhini ; Heart/drug effects/*physiology ; Heart Rate ; Humans ; Myocardium/*metabolism ; Oxidation-Reduction ; Pentosephosphates/*metabolism ; Phosphogluconate Dehydrogenase/metabolism ; Rabbits ; Rats ; Ribose/*pharmacology ; Species Specificity
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  • 112
    Publication Date: 1984-05-25
    Description: The effect of serum on the rate of substrate oxidation by dissociated brain cells in vitro was examined. At a serum protein concentration of approximately 0.55 milligram per milliliter, oxidation of [6-14C]glucose to 14CO2 was decreased more than 50 percent. Oxidation of [3-14C]-3-hydroxybutyrate and [U-14C]glutamine was decreased much less. Serum from cows, rats, horses, and humans produced similar effects, as did serum from young and old animals and from both sexes. The effect on [6-14C]glucose oxidation was proportional to serum protein concentration, and significant inhibitory activity was obtained with dialyzed serum. Heating (80 degrees C for 10 minutes) significantly reduced the inhibitory activity. These results suggest the presence of a factor in serum that can preferentially decrease glucose oxidation. Such a factor would have profound implications for metabolic regulation in vivo and for studies of cells in vitro in which serum is included in the growth medium.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tildon, J T -- Stevenson, J H -- New York, N.Y. -- Science. 1984 May 25;224(4651):903-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6719124" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Blood ; Brain/*metabolism ; Cells, Cultured ; *Culture Media ; Glucose/*metabolism ; Glutamine/metabolism ; Hydroxybutyrates/metabolism ; Oxidation-Reduction ; Rats ; Rats, Inbred Strains
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  • 113
    Publication Date: 1984-07-06
    Description: An ethanol-preferring line of rats, developed by selective breeding, consumed as much as 9.4 +/- 1.7 grams of ethanol per kilogram of body weight per day through intragastric self-infusions, yielding blood ethanol concentrations of 92 to 415 milligrams per 100 milliliters. By contrast, the ethanol- nonpreferring line self-administered only 0.7 +/- 0.2 gram per kilogram per day. These findings indicate that the reinforcing effect of ethanol is postabsorptive and is not mediated by the drug's smell or taste. Hence the ethanol-preferring line of rats may be suitable animal model of alcoholism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Waller, M B -- McBride, W J -- Gatto, G J -- Lumeng, L -- Li, T K -- AA-03243/AA/NIAAA NIH HHS/ -- MH-00203/MH/NIMH NIH HHS/ -- New York, N.Y. -- Science. 1984 Jul 6;225(4657):78-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6539502" target="_blank"〉PubMed〈/a〉
    Keywords: Alcohol Drinking ; Alcoholism/*physiopathology ; Animals ; Disease Models, Animal ; Ethanol/*administration & dosage/blood/metabolism ; Humans ; Male ; Rats ; Rats, Inbred Strains ; Reinforcement (Psychology) ; Stomach/metabolism
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  • 114
    Publication Date: 1984-03-30
    Description: The effect of the anion associated with sodium loading on the development of hypertension in the Dahl salt-sensitive rat was determined. For 5 weeks rats were fed a diet containing normal or high concentrations of sodium chloride or high concentrations of sodium provided as a mixture of sodium bicarbonate, phosphate, and amino acids. After 1 week on these diets and until the end of the study the rats receiving high concentrations of sodium chloride had higher systolic blood pressures than the rats in the other two groups. There were no statistically significant group differences in plasma volume, arterial pH, or plasma concentrations of Na+, K+, Cl-, Ca2+, or creatinine, or in renomedullary prostaglandin E2 production. Compared to the animals receiving normal concentrations of sodium chloride, those receiving high concentrations of sodium chloride or amino acids showed decreased plasma renin activity and plasma aldosterone concentrations. Thus, the anion ingested with sodium alters the development and severity of hypertension in the Dahl salt-sensitive rat.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Whitescarver, S A -- Ott, C E -- Jackson, B A -- Guthrie, G P Jr -- Kotchen, T A -- AM-32395/AM/NIADDK NIH HHS/ -- HL-00941/HL/NHLBI NIH HHS/ -- HL-22390/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1984 Mar 30;223(4643):1430-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6322303" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bicarbonates/adverse effects ; Blood Pressure/drug effects ; Chlorides/*adverse effects ; Diet ; Hypertension/*chemically induced ; Kidney/physiopathology ; Loop of Henle/physiopathology ; Male ; Phosphates/adverse effects ; Rats ; Rats, Inbred Strains ; Sodium Bicarbonate ; Sodium Chloride/adverse effects
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  • 115
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-01-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rottenberg, H -- Waring, A -- Rubin, E -- New York, N.Y. -- Science. 1984 Jan 13;223(4632):193-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6691147" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Ethanol/*pharmacology ; Intracellular Membranes/*drug effects ; Membrane Fluidity/drug effects ; Mitochondria, Liver/*drug effects ; Rats
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  • 116
    Publication Date: 1984-05-25
    Description: Polypeptide analogs of the known members of the corticotropin-releasing factor (CRF) family were synthesized and tested in vitro and in vivo for enhanced potency or competitive antagonism. Predictive methods and physicochemical measurements had suggested an internal secondary alpha-helical conformation spanning about 25 residues for at least three members of the CRF family. Maximization of alpha-helix-forming potential by amino acid substitutions from the native known sequences (rat/human and ovine CRF, sauvagine, and carp and sucker urotensin 1) led to the synthesis of an analog that was found to be more than twice as potent as either of the parent peptides in vitro. In contrast, certain amino-terminally shortened fragments, such as alpha-helical CRF or ovine CRF residues 8 to 41, 9 to 41, and 10 to 41, were found to be competitive inhibitors in vitro. Selected antagonists were examined and also found to be active in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rivier, J -- Rivier, C -- Vale, W -- AA03504/AA/NIAAA NIH HHS/ -- AM20917/AM/NIADDK NIH HHS/ -- AM26741/AM/NIADDK NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1984 May 25;224(4651):889-91.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6326264" target="_blank"〉PubMed〈/a〉
    Keywords: Adrenocorticotropic Hormone/secretion ; Animals ; Binding, Competitive ; Chemical Phenomena ; Chemistry ; Corticotropin-Releasing Hormone/*antagonists & inhibitors ; Rats
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  • 117
    Publication Date: 1984-07-20
    Description: Adult rats with bilateral lesions of the caudate nucleus were treated with GM1 ganglioside. Although animals injected with a control solution were severely impaired in their ability to learn a complex spatial task, those treated with ganglioside were able to learn spatial reversals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sabel, B A -- Slavin, M D -- Stein, D G -- New York, N.Y. -- Science. 1984 Jul 20;225(4659):340-2.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6740316" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*drug effects ; Brain Injuries/*drug therapy/psychology ; Caudate Nucleus/drug effects/injuries ; G(M1) Ganglioside/pharmacology/*therapeutic use ; Gangliosides/*therapeutic use ; Humans ; Learning/drug effects ; Male ; Rats ; Rats, Inbred Strains
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  • 118
    Publication Date: 1984-10-26
    Description: Application of information derived from a three-dimensional model of vasopressin bound to its antidiuretic receptor resulted in the design and synthesis of a bicyclic vasopressin analog, [5,8-cyclo(1-beta-mercaptopropionic acid,2-phenylalanine,5-aspartic acid,8-lysine)]vasopressin. The analog acts as an antagonist of the antidiuretic activity of vasopressin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Skala, G -- Smith, C W -- Taylor, C J -- Ludens, J H -- New York, N.Y. -- Science. 1984 Oct 26;226(4673):443-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6541806" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arginine Vasopressin/*analogs & derivatives ; Lypressin/*analogs & derivatives ; Male ; Rats ; Rats, Inbred Strains ; Structure-Activity Relationship
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 119
    Publication Date: 1984-04-20
    Description: Local rates of cerebral glucose utilization were measured in rats by the quantitative 2-deoxy-D-[14C]glucose autoradiographic method during electrical stimulation of the ventral tegmental area. Rats trained in intracranial self-stimulation showed a pattern of changes in forebrain metabolic activity distinctly different from the pattern seen in rats stimulated by the experimenter. These findings provide information about the distribution of local cerebral activity specific to reinforced instrumental behavior.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Porrino, L J -- Esposito, R U -- Seeger, T F -- Crane, A M -- Pert, A -- Sokoloff, L -- New York, N.Y. -- Science. 1984 Apr 20;224(4646):306-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6710145" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autoradiography ; Behavior, Animal ; Brain/*metabolism ; Deoxy Sugars/*metabolism ; Deoxyglucose/*metabolism ; Diencephalon/metabolism ; Electric Stimulation ; Male ; Rats ; Rats, Inbred Strains ; Reinforcement (Psychology) ; *Reward ; Self Stimulation/*physiology ; Telencephalon/metabolism
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 120
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-08-17
    Description: Enkephalin distribution was examined in autonomic areas of the rat thoracic spinal cord. The localization of enkephalin fibers coincided with nuclear regions containing sympathetic preganglionic neurons. Horizontal sections revealed a pattern for enkephalin fibers resembling Laruelle's description of the localization of sympathetic preganglionic neurons as rungs of a ladder.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Romagnano, M A -- Hamill, R W -- New York, N.Y. -- Science. 1984 Aug 17;225(4663):737-9.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6463650" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Autonomic Fibers, Preganglionic/physiology ; Cats ; Colchicine ; Enkephalins/*physiology ; Female ; Male ; Rats ; Rats, Inbred Strains ; Spinal Cord/*physiology ; Sympathetic Nervous System/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 121
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1984-01-13
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Siiteri, P K -- New York, N.Y. -- Science. 1984 Jan 13;223(4632):191-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6318319" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Female ; Hormones/*metabolism ; *Radioligand Assay ; Rats ; Rats, Inbred Strains ; Receptors, Cell Surface/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 122
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    Helvetica Chimica Acta 67 (1984), S. 47-53 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The He(Iα) photoelectron (PE) spectra of tris(perfluorocyclobuta)benzene 4(F)3,3,4,4,7,7,8,8,11,11,12,12-Dodecafluorotetracyclo[8.2.0.02,5.06,9]dodeca-1,5,9-triene, tris(perfluorocyclopenta)benzene 5(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-Octadecafluoro-2,3,4,5,6,7,8,9-octahydro-1H-trindene., tetrakis(perfluorocyclobuta)cyclooctatetraene 6(F)3,3,4,4,7,7,8,8,11,1l,l2,l2,l5,15,16,16-Hexadecafluoropentacyclo[12.2.0.02,5.06,9.010,13]hexadeca-1,5,9,13-tetraene., and of tetrakis(perfluorocyclopenta)cyclooctatetraene 7(F)1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-Tetracosafluoro-1,2,3,4,5,6,7,8,9,10,11,12-dodeca-hydrotetracyclopenta[a,c,e,g]cyclooctene. are reported. A tentative assignment of the PE spectra is derived by empirical correlation with those of relevant reference compounds. The results suggest that 6(F) retains the D4h-conformation in the gas phase, i.e. A conformation with a planar cyclooctatetraene ring, as observed in the crystal. All four compounds exhibit a sharp increase of their first ionization energies, relative to the corresponding parent hydrocarbons, due to the perfluoro effect.
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  • 123
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ligand 2,11-bis(diphenylphosphinomethyl)benzo[c]phenanthrene (1) has been used to prepare complexes of the type [PtL(1)] (L = C2H4, CH2=CH—CO2Me, PhC≡CPh, MeC≡CMe, MeO2CC≡CCO2Me, (i-Pr)O2CC≡CCO2(i-Pr), Ph3P and CO). It is shown that these complexes are less labile than the corresponding species [PtL(Ph3P)2]. The preparation of complexes trans-[PtX(R)(1)] by oxidative addition of RX (RX = PhCH2Br and Mel) to [Pt(C2H4)(1)] is described. The isolation of [PtO2(CH3)2CO(1)] is also reported.
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  • 124
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical anions of the compounds N1N, N3N and N5N, in which two naphthalen π-systems are separated by 1, 3 and 5 spirobonded cyclobutane rings, respectively, and tha tof the reference compound N1, containing one naphthalene π-system and one cyclobutane ring, have been studied by ESR and ENDOR spectroscopy under a variety of experimental conditions. The intramolecular electrons spin transfer between the two π-moieties in N3N.⊖ and N5N.⊖ is slow on the hyperfine time-scale, irrespective of the applied conditions. It is also slow in N1N.⊖, except for media of high solvating power. In such media, with a slight reduction of N1N to its radical anion, a paramagnetic species is observed, the hyperfine data for which are consistent with N1N to its radical anion, a paramagnetic species is observed, the hyperfine data of which are consistent with N1N.⊖, undergoing a fast intramolecular electron spin tansfer. The ESR and ENDOR spectra of this species are superimposed on those characteristic of a slow transfer. It is suggested that the fast and slow transfer involve the syn- and anti-conformations, respectively, since the distance, r, between the two naphthalene π-systems of N1N.⊖ is considerably shorter in the former than in the latter (r = 740 vs. 880 Pm for the distance between the centres of the π-systems). Glassy solutions of exhaustively reduced N1N display signals of the dianion triplet state, whereas no such signals are found for N3N and N5N. The zero-field splitting parameter, D, is 4.7 mT, corresponding to r ≈ 480 pm.
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  • 125
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Loss of CH3., CH4, C2H4, C3H5., C3H6 and C3H7 from the molecular ions of a number of 13C-labeled analogs of 4,4-dimethyl-1-pentene was studied both in normal (source) 70-eV electron impact (EI) spectra dn in metastable spectra. For loss of CH3. in the source, 96% of the methyl comes frm positions of 5, 5′ and 5″, while the remainder comes from position 1. In the metastable spectra, loss of C-1 (16%) and C-3 (9%) is increasing in importance. The loss of ethylene is a particular case: either C-1 or C-3 are lost with any other C-atom from positions 2,5,5′, and 5″ (8 × 10%) in the metastable spectra, the probability for simultaneous loss of C-1 and C-3 being 6%. If C-1 seems to these two positions become completely equivalent in the metastable time range. The T-values (kinetic energy release) for the different positions show small, but statisticaly different values and a small isotope effect. Loss of C3H5 (allylic cleavage) is 100% C-1, C-2 and C-3, i.e., no evidence for skeletal rearrangement is seen. This is also true for loss of C3C6 (McLafferty rearrangement) within the source, but in metastable decay the other positions gain in importance. The neutral fragment C3H7. appears to be the the result of consecutive loss of CH3. and C3H4, rather than a one-step loss of propyl radical or the inverse reactions sequence. No metastable reaction can be seen for this reaction. Decomposition of labeled C6H11+ and C5H10+ secondary ions occurs in an essentially random fashion.
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  • 126
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    Helvetica Chimica Acta 67 (1984), S. 450-454 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Up to now the synthesis of para-substituted phenyl-terpyridine ligands was difficult with respect to the purification of the reaction products. We have found that these compounds can easily be isolated as hydrobromides from acetic acid. Starting from the hydrobromides the purification turned out to be easy. Synthesis of para-substituted Cl-, Br-, H3C-, H2BrC-, HO- 2,6-Bis(2-pyridyl)-4-phenylphyridine is reported.
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  • 127
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    Helvetica Chimica Acta 67 (1984), S. 441-449 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Complexation of Silver(I) by Cyclic TetraminesThe nature of Ag(I)-complexes with 1,4,8,11-tetraazacyclotetradecane (1), 1,5,9,13-tetraazacyclohexadecane (2) 1,5,10,14-tetraazacyclooctadencane (3) and 1,6,11,16-tetraazacycloeicosane (4) is studied. The effect of ring size on disproportionation of the Ag() cation in the presence of ligand is reported. The stability of Ag(I)-complexes with 3 and 4 in aqueous solution is determined by means of potentiometric titration.
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  • 128
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    Helvetica Chimica Acta 67 (1984), S. 625-627 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 129
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    Helvetica Chimica Acta 67 (1984) 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 130
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    Helvetica Chimica Acta 67 (1984), S. 625-639 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Radical Ions of Bridged [14] Annulenes. Investigations on the Influence of Frontier Orbitals on Reactivity and BondingThe radical anions and the radical cations derived from trans-15, 16-dimethyl-1, 4:8,11-ethandiyliden[14]annulene (6), trans-15-methyl-1,4:8,11-ethandiyliden[14]annulene (7) and cis-15, 16-propano-1,4:8,11-ethandiyliden[14]annulene (8) are described. The hyperfine data of the radical anions 6, 7 and 8 resemble those of the structurally related radical anions of trans-10b, 10c-dimethyldihydropyrene (4) and trans-10b, 10c-dihydropyrene (5). This finding leads to the conclusion, that the change in the relative arragement of the saturated bridge within the fourteen-membered π-perimeter by passing from 4 (5) to 6 (7, 8) does not in fluence the energetic sequence of the lowest unoccupied molecular orbitals. The behavior of 6 and 7 towards oxidation parallels the photochemical reactivity of 4. The hyperfine coupling constants of the radical cations derived from 6 and 7 indicate that the removal of an electron is accompanied by an isomerization of the molecular framework. The investigation of the electron transfer process gby cyclic voltammetry supports these findings. The radical cations prefer the cyclophane-like structures 6a and 7a, in which the central σ-bond (C(15)-C(16) bond) is broken.
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  • 131
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    Helvetica Chimica Acta 67 (1984), S. 664-668 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemical behaviour of the title compound 1a is compared to that of the non-fluorinated parent ketone 2-methylcyclohexanone (1b). Substitution of the CH3- group on C(2) by a trifluoromethyl group strongly enhances 2H- and RH- reduction product formation in cyclohexane or 2-propanol and oxetane formation in the presence of 2-methylpropene as olefinic component. Under all these conditions 1b exclusively undergoes a-cleavage, a process observed for 1a only in non-reducing solvents as benzene or tert-butyl alcohol.
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  • 132
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of β-keto-acetals, derived from non-enolisable β-diketones, with sulfonic acids in boiling benzene resuots in a smooth retro-Claisen-type fragmentation. The acetal-C-atom is thereby transformed into a carboxylic ester via a dialkoxycarbenium ion, which is dealkylated by the sulfonate counter-ion. Application of this reaction to the diastereomeric monoacetals 3 and 4, derived from cis-9-methyl-decalin-1,8-dione (1), followed by transesterification with CH3OH, yields optically pure 4-(2′-methyl-3′-oxocyclohexyl)butyrate 9 ((+)-9 from 3, (-)-9 from 4) and the monosulfonate of Meso-2,3-butanediol (-)-13 (Scheme 2). Unexpectedly, this cleavage proceeds as well with monoacetal 26, obtained by acetalization of trans-9-methyl-decalin-1,8-dione (27) with 2,2-dimethyl-1,3-propanediol (Scheme 7). Some attempts, aiming at an isomerization of the cis- and trans-decalin derivatives 3 and 24, or 25 and 26, via the postulated carboxonium intermediate, were not successful.
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  • 133
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    Helvetica Chimica Acta 67 (1984), S. 856-865 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alkylation of bicyclo[3.3.0]octane-2,8-dione (1), which is prepared by a modification of the procedure described in the literature, gives the methyl- and propynyl-derivatives 6 and 7 (Scheme 1). In addition to the method described previously (Scheme 2), 9-methyl-cis-decalin-1,8-dione 9 is obtainable stereoselectively either by cyclization of keto-acid 16, or by aldol cyclization of keto-aldehyde 26 and oxydation of the resulting alcohols 24 and 25 (Scheme 4). The β-keto-alcohols 24 and 25 undergo a base-catalyzed isomerization; the trans-decalin isomers 27 and 28 are not detected in this equilibrium mixture (Schemes 4 and 5)l. Monoreduction of cis-dione 9 gives the endo-alcohol 25, while 27 is the favored product of the reductin of trans-dione 10 (Scheme 4). Optically pure (+)-25 can be prepared from (9S,10R)-monoacetal 29 (Scheme 5).
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  • 134
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new tripeptide (dimer), bis[(L-cysteine-S-acetyl)-L-hemicystinyl(S2 → S2)-D-valine] (6) was synthesized by coupling N-(tert-butoxycarbonyl)-S-carboxymethyl-L-cysteine benzyl ester (1) with S-trityl-L-cysteinyl-D-valine benzyl ester and subsequent removal of the protecting groups. After reduction of the disulfide, the free tripeptide Cys (CH2CO-Cys-D-Val) (Ib) was used as a substrate of isopenicillin-N synthetase in a cell-free conversion to 6-[2-((D-2-amino-2-carboxyethyl)thio)acetamido]penicillanic acid (IIa).
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  • 135
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    Helvetica Chimica Acta 67 (1984), S. 902-905 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the title compounds is described.
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  • 136
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    Helvetica Chimica Acta 67 (1984), S. 927-927 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 137
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)- and (-)-5, as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (-)-1, are described. X-Ray single-crystal analysis reveals (2S, 3S) absolute configuration of (+)-1 on the basis of tentative comparison of CD data with those for the 1,4-benzodiazepine derivative (+)-8 of known absolute configuration.
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  • 138
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    Helvetica Chimica Acta 67 (1984) 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 139
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    Helvetica Chimica Acta 67 (1984), S. 927-933 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis ad Structure of Zinc Complexes of 2-Amino-1-azetinesThe 2-dimethylamino-3,3-dimethyl-1-azetines 7a and 7b have been synthesized in analogy to the procedure reported by Ghosez et al. [1] (Scheme). The crystal structure of 1-benzhydryl-azetidindimethyliminium chloride 5a, a precursor of azetine 7a, has been established by X-ray diffraction analysis. Treatment of azetines 7a and 7b with ZnBr2 in CH2Cl2/MeCN yielded tetrahedral bis (azetine)dibromozinc complexes 8a and 8b, respectively (Scheme 2). The molecular structure of 8a has been determined by X-ray diffraction analysis too.
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  • 140
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    Helvetica Chimica Acta 67 (1984), S. 947-952 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective synthesis of (+)- and (-)-cis-2-methyl-4-propyl-1,3-oxathine 8 and 9 form (E)-2-hezen-1-ol (1) as common starting material is described. The two enantiomeric forms exhibit different organoleptic properties.
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  • 141
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    Helvetica Chimica Acta 67 (1984), S. 959-963 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cyanothyl-subsituted cylohexyl cyclohexanoates, bi(cyclohexanes) and phenyl cyclohexanes were synthisized. Their mesmorphic behaviour is compared to that of the corresponding cyano derivatives. (Cyanoethyl)cyclohexyl cyclohenxanoates show mesmorphic properties in contrast to the corresponding cyano derivative. Separation of the cyano substituent from the rigid core of an anisotropic aliphatic compound by methylene groups enhances the thermodynamic stability of the mesophase. In aromatic compound, the cyanoethyl group leads to lower clearing points. These phenomena are attributed to teh influence of steric effects on the packing density and to the dependence of the clearing point on molecular association.
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  • 142
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    Helvetica Chimica Acta 67 (1984), S. 1000-1002 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nα-L-Iysine with a 2-carboxy-4, 6-dinitrophenyl (Dncp) haptenic group on the ε-amino function is a potent anaphylactogen in the guinea pig. We prepared Nε -Dncp- Nα-benzoly-L-Iysinamide and Nε-Dncp-Nα-benzoyl-L-lysyl-1-aminopropane where the carboxyl group of Iysine is blocked. Both compounds were non-elections of anaphylaxis.
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  • 143
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    Helvetica Chimica Acta 67 (1984), S. 21-28 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: C45- and C50-Carotenoids. Synthesis of Optically Active Acyclic C15-End GroupsThe optically active C15-end groups (S)-12, (S)-13 and (R)-14 were prepared from the C12-synthon (S)-11 in good chemical and optical yield. These C15-end groups are suitable compounds for the synthesis of optically active C45- and C50-carotenoids.
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  • 144
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    Topics: Chemistry and Pharmacology
    Notes: In the crystal structure of the title compound at 98 K the dimethylamino group has pyramidal geometry. The nitrogenlone pair is not directed towards the triple bond; instead, one N—CH3 bond lies almost in the plane of the disubstituted ring, directed away from the triple bond, while the other N—CH3 bond and the lone pair are directed to opposite sides of the plane, nearer to the acetylene. There is a remarkably short intramolecular contact (2.39 Å) between a methyl H- and an acetylenic C-atom. The Taft σI parameter of the arylethynyl substituent appears to be similar to that of a carboxylic ester, judging from the bond-angle deformation at the ipso-C-atom.
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  • 145
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHERFrom the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and 1- and 13C-NMR spectroscopy. Besides the known k-Strophanthidin (1), Antiarigenin (6) and β-Antiarin (Antiarigenin-3-β-O-α-L-rhamnoside, 10) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D-allopyranoside (strophalloside, 2), strophanthidin-3-β-O-β-6-desoxy-D-glucopyranoside (= Strophanthidin chinovoside, 3), strophanthidin-3-β-O[-4Oβ-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (4), strophanthidin-3-β-O-[3-O-β-D-glucopyranosyl-β-6-desoxy-D-talopyranoside] (5), antiarigenin-3-β-O-[3-O-β-D-gulopyranosyl-β-6-desoxy-D-talopyranoside] (7), antiarigenin-3-β-O-[4O-β-D-allopyranosyl-β-6-desoxy-D-allopyranoside] (8), and antiarigenin-3-β-O-β-6-desoxy-D-allopyranoside (antiallosid) (9). The structure of strophanthidinchinovoside (3) could be confirmed by synthesis.
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  • 146
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    Keywords: Chemistry ; Organic Chemistry
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    Topics: Chemistry and Pharmacology
    Notes: A recent controversy on the interpretation of the ESR spectrum of ionized oxirane is clarified on the basis of the electronic absorption spectra of ionized tetramethyloxirane and 9,10-octalineoxide. The results favour a ring-opened structure for oxirane molecular cation, resulting from C—C bond cleavage and being iso-π-electronic to allyl radical.
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  • 147
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Acylation of Acetylenes with β,γ-Unsaturated Acid Chlorides, A New Synthesis of 5-Substituted 2-CyclopentenonesThe acylation of acetylenes with α,α-disubstituted, β,γ-unsaturated acid chlorides under Friedel-Crafts-type conditions leads to 5-substituted 2-cyclopentenones. Phenols are formed with β,γ-unsaturated acid chlorides bearing at least one α-H-atom. These transformations are explained by the intramolecular cyclization of the initially formed vinyl cation, which, in the cases of α,α-disubstituted acid chlorides, is followed by ring contraction. The reaction leading to 2-cyclopentenones is applied to the synthesis of some spiro[4.4]nona- and spiro[4.5]deca-2,6-dienones.
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  • 148
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    Helvetica Chimica Acta 67 (1984), S. 113-119 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Arylazonaphthalenes with all the potential cyclopalladation sites (one peri- and three ortho-positions) substituted by methyl or ethyl groups react with stoicheiometric or catalytic amounts of sodium tetrachloropalladate(II) to the corresponding 2-arylbenzo[g]indazoles. Possible mechanisms for the catalytic cyclization reaction are proposed.
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  • 149
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1n, π*-Excitation of the γ,δ-epoxy-enone (E)-3 leads exclusively to the conformers (Z)-3A + B. On 1π, π*-excitation of (E)-3, in addition to (Z)-3A + B, products 6-9 arising from a carbene intermediate e are formed. However, products of an isomerization via C(γ), O-bond cleavage of the oxirane were not formed on either mode of excitation. On thermolysis, at 80° the conformer (Z)-3A is transformed into (Z)-3B, which on photolysis returns to (Z)-3A and (E)-3. At 160°, however, (Z)-3B rearranges to the isomers 6, 10 and 11.
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  • 150
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    Helvetica Chimica Acta 67 (1984), S. 866-869 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective oxidation of benzylic methylene groups through UV irradiation in acetone/water/FeCl3 mixtures is reported. This method applied to a series of model compounds, provides an easy access to the corresponding 1-oxo derivative. Thus, tetralin gives a 100% yield of 1-tetralone, indane leads to 60% of 1-indanone, and diphenylmethane is oxidized to benzophenone with 80% yield. However, under the same conditions, alkyl-substituted aromatic hydrocarbons such as toluene, ethyl- and propylbenzene lead to low yields of aldehydes or ketones. Isochromane furnishes a mixture of two substances which can be interconverted, namely the expected l-isochromanone (9%) and the corresponding hydroxy acid (23%). We failed to apply the method to nitrogen heterocycles containing benzylic groups such as 1,2,3,4- and 5,6,7,8-tetrahydroquinoline as they do not react due to the formation of complexes which precipitate from the solutions.
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  • 151
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.
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  • 152
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Business C,D,E,F,G,H,J,K,L und M, Ten New Tetranortriterpenes from Entandrophragma Bussei HarmsTen new tetranortriterpenes, busseins C, D, E, F, G., H, J, K, L and M have been isolated from the petroleum ether extract of the timber of Entandrophragma bussei Harms. utilizing separation by high-pressure liquid chromatography (HPLC). The structural assignments are based mainly on spectral evidence. For the 1H-NMR spectroscopy extensive use of nuclear Overhauser effects (NOE) was made.
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  • 153
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    Helvetica Chimica Acta 67 (1984), S. 928-930 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 154
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alcohols and phenols are efficiently nitrated with thionyl chloride nitrate or thionyl nitrate, even in the presence of an aromatic moiety. While thionyl chloride nitrate is suitable for nitration of primary OH-groups in carbohydrates, thionyl nitrate is reactive enough to react with secondary OH-groups as well. These reagents permit the highly selective nitration of the 5′-,2′5′- and 3′, 5′-OH-groups of ribonucleosides to produce either mono-or diprotected nitro derivatives in high yields. Carbon acids and the enol form of some ketones are efficiently nitrated with trifluoromethanesulfonyl nitrate/potassium tert-butoxide. Lutidine N-oxide (2,6-(CH3)2C5H3N O) was found to have a marked effect on nitration reactions. Similarly, thionyl chloride nitrite and thionyl nitrite exhibit an excellent capacity for nitrosation of the aforementioned substrates.
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  • 155
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    Helvetica Chimica Acta 67 (1984), S. 934-938 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The radical cations and the radical of 1,2-bis(phenalen-1-ylidene)ethane (1), 1,2-bis(phenalen-1-ylidene)ethene (2) and pentaleno[1,2,3-cd: 4,5,6-c′ d′]diphenalene (3) have been characterized by ESR and ENDOR spectroscopy. The ease of formation of these radical ions and their π-spin distributions are interpreted in terms of a simple model correlates the frontier orbitals of 1, 2 and 3 with the nonbonding MO's of two phenalenyl π-systems.
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  • 156
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    Helvetica Chimica Acta 67 (1984), S. 939-946 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of 1-(2-propynyl)pyridinium salts 3 described. Compounds 3 react with a second pyridine molecule, in the presence of the corresponding hydrochloride, to form products of type 4, Certain bases cause the 1-(2-propynyl)pyridinium salts 3 to rearrange into 1-propadienylpyridinium salts. 5. Diethylamine converts compounds 3 into 1-acetonylpyridinium salts 8. Moreover, treatment of 3 or 5 with sodium methoxide gives enol ether sof type 9, which can be hydrolyzed to teh ketones 8. Addition of bromine to some of teh unsaturated compounds is also reported.
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  • 157
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    Helvetica Chimica Acta 67 (1984), S. 953-958 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: IR-spectroscopic investigations of light-induced rearrangement reactions of nitrosooxymethane (CH3ONO3), nitrosooxyethane (CH3CH2ONO) and N,N-dimethylnitrosamine ((CH3)2NNO) in low-temperature rare-gas matrices have established that these molecules are transformed in two photolysis steps to the previously unknown C-nitroso compounds nitrosomethanol (CH2(OH)(NO)), 1-nitrosoethanol (CH3CH(OH)(NO)), and methyl(nitrosomethyl)amine CH2(NO)(NH)(CH3). Evidence for a similar rearrangement reaction has been advanced for N-Nitrosopyrrolidine which is converted to C-nitrosopyrrolidine . The matrix-isolation technique in combination with wavelength-selective irradiation allowed to trap and characterize an intermediate of rearrangement which revealed to be nitroxyl (HNO) complex (CH2…HNO, CH3CHO…HNO, CH3N = CH2…HNO, and ). Since these findings have a close resemblance with rearrangement reactions of more complex nitrosooxy compounds, nitrosamines, or nitrosohydrazines used in organic synthesis, it is suggested that also in these reactions nitroxyl is present as an intermediate species.
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  • 158
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    Helvetica Chimica Acta 67 (1984), S. 964-967 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Isolation of 1,2-Epoxy-1,2-dihydrolycopene from TomatoesThe optically active, 1,2-epoxy-1,2-dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.
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  • 159
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Epoxycarotenoids: Synthesis, 1H-NMR and CD Studies of (S)-1,2-Epoxy-1,2-dihydrolycopene and (S)-1′,2′-Epoxy-1′, 2′ -dihydro-γ-caroteneThe synthesis of (S)-1,2-epoxy-1,2-dihydrolycopene ((S)-1) and (S)-1′, 2′ -epoxy- 1′, 2′ -dihydro-γ-carotene ((S)-2) are described. The CD spectra of the (all-E)-isomers and of the isomers (7Z, S)-1 and (7′Z, S)-2 are discussed. The comparison of the CD spectra of the synthetic (S)-1 and the compound isolated from the tomatoes proves the (S)-configuration of the natural product.
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  • 160
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    Helvetica Chimica Acta 67 (1984), S. 1003-1011 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Plectranthons A, B, C, and D. Diterpenoid Phenanthrene-1,4-diones from Leaf-glands a Plectranthus sp. (Labiatae)The following structures of four new 1,4-phenanthraquionones, isolated in minute amounts from the coloured leaf-glands of a Plectranthus sp. obtained from the borders of Lake Kiwu2, Rwanda, are proposed: plectranthon A (1; 3-hydroxy-5, 7,8-trimethyl-2-(2-propenyl)phenanthrene-1, 4-dione), plectranthon B (2; 2-(2ξ-acetoxypropyl)-3-hydroxy-5,7,8-trimethylphenanthrene-1,4-dione), plextranthon C (3; 3-hydroxy- 7,8-diemethyl-2-(2-propenyl)phenanthrene-1,4-dione), and plectranthon D (4; 3-hydroxy-7,8,10-trimethyl-2-(2-propenyl)phenanthrene-1,4-dione). 2-(2ξ-Hydroxypropyl)-3,6-dihydroxy-5,7,8-trimethylphenanthrene-1,4-dione (11), a compound very similar to 1-4, was prepared by a Wagner-Meerwein, rearrangement of coleon E (5). Biogenetically, the plectranthons are derived from abietanoic precursors. The compounds 1, 2 and 4 are the first natural C20-phenanthrenes of diterpenoid origin.
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  • 161
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    Keywords: Chemistry ; Organic Chemistry
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    Topics: Chemistry and Pharmacology
    Notes: Oxidative hydroboration of exo- (1) and end-Fe(CO)3 (2) complexes of 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene are highly stereoselective and give endo -alcohol 3 and exo -alcohol 4 as major products, respectively, Collins oxidations of 3 and 4 furnish the corresponding exo -Fe(CO)3 -complexed 5,6-dimethylidene-2-bicyclo-[2.2.2]octanone 7 and 8. NaBH4 reduction of exo-complexes 7 gives a mixture of 3 and isomeric exo-alcohol 18, whereas reduction of endo-complexes 8 gives the endo-alcohol, endo-complexes 19, as the sole product. The base-catalyzed H/D exchange of 7 and 8 afford the dideuterated exo-complex 35 and the monodeuterated endo-complex 32, respectively. Oxidative hydroborations of the exo-(9) and endo-Fe(CO)3 (10) complexes of 5,6-dimethylidenebicyclo[2.2.1]hept-2-ene give the corresponding exo-alcohols 39 and 40. Oxidation of 39 and 40 gives the exo- and endo-complexes 41 and 42, respectively, of 5,6-dimethylidene-2-bicyclo[2.2.]heptanone. Only Hexo —C(3) can be exchanged in 42, wheres both H-atoms at C(3) in 41 are exchangeable. The endo-Fe(CO)3 group in 8 and 42 blocks the base-catalyzed H/D exchange of Hendo —C(3), thus providing a test for the configuration of Fe(CO)3 group in these systems. These studies have led to a revision of the iron configurations proposed by Hansen et al, [2] for 1, 2, 9 and 10.
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    Helvetica Chimica Acta 67 (1984), S. 361-364 
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    Keywords: Chemistry ; Organic Chemistry
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    Topics: Chemistry and Pharmacology
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  • 163
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvolysis rate constants in MeOH and t-BuOh are compared for β-methyl and β-phenyl derivatives of two cycloakyl systems. It appears that the β-phenyl derivatives solvolyse at te same rate as the β-methyl ones. The lack of deceleration is attributed to phenyl assistance. It is established by configurational analysis of the reaction products, that those products which necessarily originate from a cationic species are the most abundant ones. It is suggested that these reactions could proceed through ion-pair intermediates, which are nucleophilically solvated by phelyl or by the solvent. A parallel between phenyl assistance and ‘SN2 (intermediate)’ mechanism, suggested by Bentely & Schleyer, is drawn.
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  • 164
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    Helvetica Chimica Acta 67 (1984), S. 361-372 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of the water self-diffusion coefficients (D), as well as those of low- and high-field (stationary and time-dependent) specific conductivities (K), have been determined in the percolation regime of ternary mixtures of water, AOT, and oil. For the first time a pronounced similarity in the behavior of D and κ was detected giving instructive hints about the large variations in the specific conductivities of these systems. Results from kinetic and stationary experiments are consistent with a network-structure model of micro phases in the percolation regime in which the micro phases retain their discrete character.
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  • 165
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    Topics: Chemistry and Pharmacology
    Notes: Facile synthesis of derivatives of 2,4-diphenyl-3-azabicyclo[3.3.1]nonane and 7,9-diphenyl-8-azabicyclo[4.3.1]decaneThe facile synthesis of hydantoins, cyanhydrins and aminonitriles derived from 2,4-diphenyl-3-azabicyclo[3.3.1]nonanone and 7,9-diphenyl-8-azabicyclo[4.3.1]decanone is described. Configurations at C(9) or C(10) of the new compounds wth pharmaceutical and synthetical utility is deduced from their spectral properties.
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  • 166
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    Helvetica Chimica Acta 67 (1984), S. 1328-1347 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the D-arabino- and D-ribo-ortholactones 13a-f and 15b-f and their treatment with Zn leading to the unsaturated esters 14a-d and 16a-d are described. Possible fragmentation mechanisms are discussed. The results were only compatible wit a concerted, nonsynchronous process, where both the axial lone pair of the ring oxygen atom and the lone pair formed during rupture of the C(5), O-bond participate in the elimination of the axial and of the equatorial C(1)-alkoxy groups, respectively.
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  • 167
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    Helvetica Chimica Acta 67 (1984), S. 1368-1373 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This communication reports ESR-spectroscopic investigations of the radical anion of 1,8-dimethyl[14]annulene (1) which possesses a flexible molecular framework allowing configurational and conformational mobility. The ESR and ENDOR spectra indicate that at higher temperatures (T 〉 160 K), \documentclass{article}\pagestyle{empty}\begin{document}$ 1^{- \atop \dot{}} $\end{document} exists as a mixture of several distinct isomers. One of them, the sole product at T 〈 160 K, is found to be energetically preferred. The configuration and the conformation of this species can be determined by interpretation of the hyperfine data in terms of a singly occupied MO of the 14-membered π-perimeter.
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  • 168
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    Helvetica Chimica Acta 67 (1984), S. 1386-1396 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-(tert-Butyl)-3,7-dehydrotropone (7-(tert-butyl)bicyclo[3.2.0]hepta-1(7),2,4-trien-6-one; 1) was found to dimerize reversibly to 2A by [2 + 4]-cycloaddition/cycloreversion reaction. The equilibrium lies on the side of the highly strained dimer 2A in the solid state, and on the side of the monomer 1 in solution. The [2 + 4]-reaction is fully perisite-, regio- and stereoselective. Above room temperature, 1 irreversibly formed a decarbonylated dimer 6, probably via the intermediate 9A or 9B, which resulted either from a dimerisation of 1 by [4 + 6]-cycloaddition or from a sigmatropic rearrangement of the originally formed dimer 2A or 2B. Similary, the 6-bromo derivative 14 afforded the corresponding decarbonylated dimer 15. Should the formation of 6 and 15 be due to a primary cycloaddition then that reaction is fully peri-, site- and regioselective. Mild LiAlH4-reduction of 6 and subsequent acetylation yielded the acetate 11, the structure of which was established by an X-ray analysis. More vigorous LiAlH4-treatment also reduced the terminal fulvenoid double bond of 6 and acetylation of the crude product led to the acetated 12 and 13.
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    Helvetica Chimica Acta 67 (1984), S. 1427-1428 
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    Keywords: Chemistry ; Organic Chemistry
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    Helvetica Chimica Acta 67 (1984), S. 1427-1438 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electromotive Behaviour of Liquid-membrane Electrode Assemblies Based on Enantiomer-selective Chiral IonophoresA comprehensive theoretical treatment is given for the potentiometric behavior of enantiomer-selective membrane electrodes based on chiral ionophores and plasticizers. The membrane model allows for free and complexed enantiomeric or racemic ions (e.g. ephedronium and l-phenylethylammonium ions) as well as for achiral interfering ions. Experiments are derived for the determination of the stoichiometry and the relative stability of enantiomeric ion/enantiomeric ligand complexes, and for the analytical measurement of the enantiomeric excess of ions in solution.
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  • 171
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    Topics: Chemistry and Pharmacology
    Notes: Water exchange of square-planar Pd(H2O)24+ has been studied as a function of temperature (240 to 345 K) and pressure (0.1 to 260 MPa, at 324 K) by measuring the 17/O-FT-NMR line-widths of the resonance from coordinated water at 27.11 and 48.78 MHz. The following exchange parameters were obtained: k298ex = (560 ± 40) s-1, ΔH* = (49.5 ± 1.9) kJ mol-1, ΔS* = - (26 ± 6) J K-1 mol-1 and ΔV* = - (2.2 ± 0.2) cm3 mol-1. The values refere to an aqueous perchlorate medium with an ionic strength between 2.0 and 2.6 m and a perchloric-acid concentration between 0.8 and 1.7 m, and are interpreted in terms of an associative (a) activation for the exchange. The exchange rate for Pd(H2O)24+ is 1.4 × 106 times faster than for Pt(H2O)24+ at 298 K. A comparison with reactions between other nucleophiles and Pd(H2O)24+ is also made.
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  • 172
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    Topics: Chemistry and Pharmacology
    Notes: Studies of Organometallic Compounds, XX. Selectivity of 1,4-Addition of Benzyltitanium Compounds with BenzylildenacetoneTetrabenzyltitanium and dialkoxydibenzyltitanium compounds give essentially 1,4- addition with trans-4-phenyl-3-buten-2-one.
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aminative Reductive Coupling of Aromatic Aldehydes to N,N,N′,N′-Tetraalkyl-1,2-diarylethylenediamines, Induced by Tris(dialkylamino)methylvanadium (IV)In a novel type of reaction, certain aromatic aldehydes (benzaldehyde, p-methoxybenzaldehyde, 1-naphthaldehyde, furan-2-carbaldehyde) and secondary amines are coupled to give N,N,N′,N′-tetraalkyl-1,2-diarylethylenediamines 1-6. The reagents are tris(dialkylamino)methylvanadium(IV) compounds (cf. Eqn. 2). These are generated in situ either from isolable chlorotris(dialkylamino) vanadium(IV) (Eqn. 3), or preferably, from an Et2O/pentane solution of VCl4 which is treated sequentially with 3 equiv. of lithium dialkylamide, 1 equiv. of MeLi, and 0.8 equiv. of an aromatic aldehyde, to give the products 1-6 in a one-pot preparation (Scheme 2). The yields range from 14 to 54%. The diastereoisomeric mixtures (meso- and (±)-forms) obtained are separated by chromatography (Al2O3, petroleum ether/Et2O/Et3N), and the pure stereoisomers fully characterized. A mechanism of the reductive coupling induced by CH3V (NR2)3 is proposed (Scheme 1).
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  • 174
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    Helvetica Chimica Acta 67 (1984), S. 1506-1514 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several oxidative, reductive and C,C-cleavage reactions were performed starting from the three bicyclo[4.2.1]nona-3,7-diene-2-one derivatives 1, 5 and 18. The oxidations were selective and led to the diols 2,8 and 9, and the epoxides 6,9, and 20. The reductions were selective only in the case of 20 21; otherwise they led to mixtures of the alcohols 10 and 11, and of the dienes 14 and 15. The periodate ring cleavages afforded the functionalized cycloheptane derivatives 3, 12, 13 and 16. Configurational assignments were made on the basis of detailed 1H-NMR and X-ray analysis of 20.
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  • 175
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    Helvetica Chimica Acta 67 (1984), S. 1531-1534 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Red-Coloured Abietanoids from Leaf-Glands of Plectranthus strigosus BENTH.Chromatographic examination of the red-coloured diterpenoids from the South-African title plant yielded the following compounds: parviflorone A(1), parviflorone B (2), parviflorone C(3), parviflorone E (4) parviflorone D (5), parviflorone F (6), parviflorone G (7), and parviflorone H (8). Compounds 7 and 8 represent new variants of these quinone methides.
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  • 176
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    Notes: Polar Diterpenoids from Leaf-Glands of Plectranthus argentatus S. T. BLAKEFrom the red leaf-glands of the Australian Plectranthus argentatus the following novel diterpenoids were isolated: coleon-U-quinone (1), 8α,9α-epoxycoleon-U-quinone (3), 6β-formyloxy-7α-hydroxyroyleanone (7), and 5,6-dihydrocoleon U (10), besides the already known compounds 6β, 7α-dihydroxyroyleanone (4), 7α-acetoxy-6β-hydroxyroyleanone (5), and 7α-formyloxy-6β-hydroxyroyleanone (6). Epoxydation of 1 by perborate led in 32% yield to the epoxyquinone 3.
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  • 177
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    Helvetica Chimica Acta 67 (1984), S. 1568-1571 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partially protected 4- or 5-hydroxy-sugar oximes were transformed into 5- or 6-membered 1-C-nitroglycosyl chlorides, respectively, by reaction with NaOCl under phase-transfer conditions. With the exception of the oxidation of the gluco-derivative 1 giving the anomers 6 and 7, the reactions were completely diastereoselective.
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  • 178
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    Helvetica Chimica Acta 67 (1984), S. 1572-1579 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and the liquid-crystal temperatures of sixty 4-cyano-2-fluorophenyl and 4-cyano-3-fluorophylen 4-substituted benzoates are described. The nematic-isotropic liquid transition temperatures of the most of these novel esters are only marginally lower than those of the corresponding esters containing an H-atom in place of the F-substituent. In several instances, the clearing points of the F-substiuted-phenyl esters are higher than those of the non-substituted-phenyl esters. The nematic ranges of several of the new esters are markedly broader than those of the analogous non-F-substituted-phenyl esters.
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  • 179
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    Helvetica Chimica Acta 67 (1984), S. 1588-1592 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-NMR and vapor-pressure osmometry results are presented, which indicate the occurrence of a rapid equilibrium involving the head-to-head dimerization of β44-helices in chloroform solutions of HCO-L-Ile-(D-AIle-L-Ile)4-OMe. This equilibrium typifies the one that, in Urry's view, would be responsible for the formation and breaking down of the ion-conducting channels formed by gramicidin A in lipid bilayers.
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  • 180
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    Topics: Chemistry and Pharmacology
    Notes: The synthesis and liquid-crystal transition temperatures of forty ester derivatives of 2-fluoro-4-hydroxybenzonitrile and 3-fluoro-4-hydroxybenzonitrile are reported. The esters contain the trans-1,4-disubstituted cyclohexane or the 1,4-disubstituted bicyclo[2.2.2]octane rings (some contain an additional phenyl ring). Many of the novel F-substituted esters exhibit substantially higher nematic-isotropic transition temperatures than the corresponding unsubstituted esters. The order of clearing points of these laterally substiuted esters differing only in the presence of a benzene ring and the above-mentioned rings id established.
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  • 181
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    Helvetica Chimica Acta 67 (1984), S. 1598-1602 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of New Morphine Partial Structure 15,16-SecomorphinanThe synthesis of a new morphine partial structure, 15,16-secomorphinan, is described. One of the series, (±)-15, 16-secocyclorphan (5), has the analgesic potency of morphine and exhibits good binding to the opiate receptor.
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  • 182
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    Topics: Chemistry and Pharmacology
    Notes: Diastereoselective Synthesis of Novel Mannich (Bases1) through Titanium ReagentsTrichlorotitanium dialkylamino-alkoxides (2; titanates of N, O-hemiacetals) are generated either from the corresponding lithium alkoxides and titanium tetrachloride (Scheme 1) or by addition of trichloro-dialkuylamino-titanium to aldehydes. The electrophilic (dialkylamino) alkylating reagents 2 are used to convert lithium enolates to β-dialkylamino-ketones and -esters 5 (Mannich bases), see Scheme 2 and Table. One diastereoisomer of the products 5g-5p thus obtained with cyclohexenolate is formed preferentially (66-84%). The configuration of the products of this first diastereoselective version of the Mannich reaction could not yet be determined. A typical procedure for carrying out the reaction is given.
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    Helvetica Chimica Acta 67 (1984), S. 1612-1615 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new, practical method for the optical resolution of bicyclic ketones if illusttrated by the preparation of (+)-(1R,4R)-7-oxabicyclo[2.2.1]bept-5-en-2-one ((+)-1) and (+)-(1R, 2S,4R)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yul acetate ((+)-4). It involves the diastereoselective formation of a brucine complex with the corresponding cyanhydrine mixture.
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  • 184
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    Topics: Chemistry and Pharmacology
    Notes: A series of three-coordinate bis(dialkylphosphinomethyl)benzo[c]phenanthrene Ag(I) complexes, alkyl= t-Bu, (1b), and cyclohexyl, (1c), anion = BF4, CIO4, CIO4, NO3, Cl, Br, I, have been prepared and thier 31P-NMR characteristics recorded. The solid state structures of [Ag(1b)Br], [Ag(1b)Cl] and [Ag(1b)CIO4] have been determined by X-ray diffraction. The Ag atom in these complexes shows distorted trigonal geometry. Selected bond lengths and angles are as follows: Ag-P = 2.463(4) Å and 2.433(5) Å, P-Ag-P=141.6(2)° in the bromo complex, Ag-P = 2.457(2) Å and 2.427(2) Å, P-Ag-P = 142.6(1)° ion the chloro complex, and Ag-P = 2.394(2) and 2.393 (2) Å, P-AG-P = 161.5(1)° in the perchlorato complex.
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    Helvetica Chimica Acta 67 (1984), S. 1625-1629 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new syntheses of verrucarinic acid (2S, 3R-dihydroxy-3-methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (-)-(S)-malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.
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  • 186
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    Topics: Chemistry and Pharmacology
    Notes: Control of the Catalytic Synthesis of Pyridine from Alkynes and Nitriles by the (η6-Borinato)-Nigands at Cobaltη6-Borinato groups as ligands at cobalt have unique effects on the chemo- and negioselectivity of the catalytic co-cyclization of alkynes and nitriles. The turnover number of the conversion of acrylonitrile and acetylene to give 2-vinylpyridine is considerably enhanced. Cyano compounds wih polar substitutents such as amino or thio groups can also be reacted. The homogeneous reaction of HCN with acetylene giving pyridine has been achieved for the first time.
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  • 187
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The endocyclic double bond C(2), C(3) in 5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene (1) can he coordinated selectively on its exo-face before complexation of the exocyclic s-cis-butadiene moiety. Irradiation of Ru3(CO)12 or Os3(CO)12 in the presence of 1 gave tetracarbonyl [(1R,2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]-hept-2-ene)]ruthenium (6) or -osmium (8). Similarly, irradiation of Cr(CO)6 or W(CO)6 in the presence of 1 gave pentacarbonyl[(1R, 2R, 3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]chromium (10) or -tungsten (11). Irradiation of complexes 6 and 11 in the presence of 1 led to further CO substitution giving bed-tricarbonyl-ae-bis[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene)]ruthenium (7) and trans-tetracarbonyl[(1R,2R,3S,4S)-2,3-η-(5,6-dimethylidene-7-oxabicyclo-[2.2.1]hept-2-ene)]tungsten (12), respectively. The diosmacyclobutane derivative cis-m̈-[(1R,3R,3S,4S)-(5,6-dimethylidene-7-oxabicyclo[2.2.1]hepta-2,3-diyl)]bis(tetracarbonyl-osmium) (Os-Os) (9) wa also obtained. The Diels-Alder reactivity of the exocyclic s-cis-butadiene moiety in complexs 7 and 8 was found to be significantly higher than that of the free triene 1.
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    Notes: The products generated by heating 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene (1) with Fe2(CO)9, Ru3(CO)12, Os3(CO)12, Cr(CO)3(MeCN)3, (or W(CO)5(MeCN) or by treatment with Fe-atoms have been characterized by spectroscopic methods. Apart from the expected η2- and η4-complexes of the triene 1, condensation products are formed which arise from the formal [4 + 2]-cyclodimerization of 1 involving the endocyclic double bond of one molecule and the diene moiety of a second. The [4 + 2]-cyclodimerization is catalyzed by Os3(CO)12 in MeOH and gives 1,4-epoxy-7-methoxy-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene (15)). Fe-Atoms induce a stereoselective [2 + 2]-cyclodimerization pf 1 which involves its endocyclic double bond and produces the dimer 8.
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    Helvetica Chimica Acta 67 (1984), S. 1647-1649 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of 2,3-Unsubstituted N-Acylindoles by [3,3]-Rearrangement of the N-Phenyl-O-vinylhydroxylamine DerivativesSummary, Treatment of N-phenylhydroxamic acids with vinylacetate in the presence of Li2PdCl4 affords 2,3-unsubstituted N-acylindoles via hetero-Cope-rearrangement of the intermediate N-O-vinylhydroxylamine derivatives.
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    Helvetica Chimica Acta 67 (1984), S. 1669-1669 
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    Keywords: Chemistry ; Organic Chemistry
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    Helvetica Chimica Acta 67 (1984) 
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  • 192
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    Notes: Irradiation of (RS,SR)-3-Phenyl-6-hepten-2-ol (3n) gave the photoproducts 6n-10n. Some reactions of 6n and 8n are reported. The regio- and diastereoselectivity observed in the photoreaction of substituted 5-phenylpentenes is discussed with respect to conformational preferences of the compounds to be irradiated.
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  • 193
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    Notes: A new convenient synthesis of dihydrolysergic acid is described, which allows the preparation of substituted derivatives, especially those with different substitutents in the aromatic ring. Starting from appropriately substituted 5-nitro-2-tetralones, the synthesis leads via a tricyclic isonitrile to the indole-ring closure as the last step, thus circumventing the troublesome protection/deprotection of the latter.
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  • 194
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    Notes: The portions of the N3H3 singlet potential energy surface corresponding to triaziridines (1), azimines (2) and triazenes (3) have been calculated by ab initio SCF using 3-21G, 6-31G, and 6-31G** basis sets. Minima and transition states were located by force gradient geometry optimization. The most important computation results are: (1) Triaziridines (1): The configuration at the 3 N-atoms is pyramidal. There are 2 stereoisomers, 1a and 1b. The c,t-isomer 1a has less energy than the c,c-isomer 1b. The 2 stereoisomerizations by N-inversion hve rather high activation energies. The N,N bonds in 1 are longer and weaker (STO-3G estimation) than in hydrazine. The N-homocycle 1 exhibits less ring strain than the C-homocycle cyclopropane or three-membered heterocycles. (2) Azimine (2): All 6 Atoms are in the same plane. There are 3 stereoisomers, 2a, 2b, and 2c. The order of ground state energies is (Z,Z) 〈 (E,Z) ≫ (E,E). The 2 N,N bond lengths correspond to multiplicity 1½. The electronic structure of 2 corresponds to a 1,3-dipole with almost equal delocalization of the 4 π-electrons over all 3 N-atoms. The negative net charge at the central N-atom is much less than that at the terminal N-atoms. Azimines should behave as π-donors in complexation with transition metals (3) Triazene (3): All 6 atoms are in the same plane. There are 2 stereoisomers, 3a and 3b. The order of ground-state energies is (E) 〈 (Z). The stereoisomerization proceeds as pure N-inversion. N-Inversion has a high energy barrier inversion at N(1) is faster than at N(2). One of the N,N bond lengths is typical for a double, the other for a single bond. The electronic structure of triazene 3 entails rather localized π- and p-electron pairs at N(1),N(2) and at N(3). Triazenes should behave as p-donors in complexation with transition metals. (4) -N3H3-Isomers: The order of ground-state energies is 3 〈 2 〈 1. The energy differences between these constitutional isomers are much larger than between the stereoisomers of each. The [1,2]-H shifts for conversions of 2 to 3 and the [1,3]-H shift for tautomerization of 3 have relatively high activation energies; both shifts can be excluded as modes of thermal, unimolecular transformations.
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    Helvetica Chimica Acta 67 (1984), S. 1952-1956 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of 4-hydroperoxy-2,4,6-trimethylcyclohexa-2,5-dienone with acetaldehyde using trimethylsilyl trifluoromethanesulfonate as catalyst gives 1,1′-bis[(1,3,5-trimethyl-4-oxo-2,5-cyclohexadienyl) peroxy]diethyl ether (7) in 70% yield. The structure of this unusual acetal was determined by X-ray analysis.
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  • 196
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    Notes: The structures of the antimalarials dihydroqinghaosu (2), artemether (3), and artesunic acid (7a) derived from qinghaosu were elaborated by 1H-NMR spectroscopy, and supported with X-ray data obtained for 2 and 3. Several new derivatives, useful for the chemical characterization of dihydroqinghaosu (2) and artesunic acid (7a), were prepared.
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    Helvetica Chimica Acta 67 (1984), S. 1562-1567 
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    Keywords: Chemistry ; Organic Chemistry
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    Topics: Chemistry and Pharmacology
    Notes: The chain elongation of the deoxy-nitroribose 6 by a Michael addition to the vinyl-phosphonate 7 followed by a solvolysis gave the heptulosephosphonate 11 (87%). From 11, the key intermediates 15 and 16 (77%) were obtained by a highly diastereoselective reduction, followed by detritylation, periodate cleavage, and silylation. Methoxycarbonylation of 15 and 16 gave 17 and 18 which were converted into methyl shikimate (21; 79%) by intramolecular olefination and partial deprotection. Similarly, phosphonoylation of 16 gave 22 (99%) which was transformed into the diethyl phosphashikimate 2 (53% from 6).
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    Helvetica Chimica Acta 67 (1984), S. 2029-2030 
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    Keywords: Chemistry ; Organic Chemistry
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    Helvetica Chimica Acta 67 (1984), S. 2028-2028 
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    Keywords: Chemistry ; Organic Chemistry
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    Helvetica Chimica Acta 67 (1984) 
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