- Azodioxide radical cations
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This report provides the first examples of solution-stable azodioxide radical cations and describes their direct spectroscopic observation and, in one case, their thermal chemistry. The formal oxidation potentials, Eo′, for N,N′-dioxo-2,3-diazabicyclo[2.2.2]oct-2-ene (3), N,N′-dioxo-2,3-diazabicyclo[2.2.1]hept-2-ene (4), and N,N′-dioxo-1,1′-azobis(norbornane) (5) are 1.65, 1.68, and 1.54 V vs SCE, respectively. ESR spectroscopy shows the intermediate cations to be π radicals. Radical cation 5?+ (red, λm 510 nm) has a five-line ESR spectrum of a(2N) 1.1 G, while 3?+ (bronze) has a nine-line ESR spectrum simulated as a(4H) 0.86 and a(2N) 1.22 G. Both 3?+ and 5?+ decay in seconds to minutes at room temperature. Thermal decomposition of 5?+ results in C,N and N,N bond cleavage, yielding 1-norbornyl cation (trapped by solvent) and NO+ (trapped in low yield by the oxidant under chemical oxidation conditions). Two viable mechanisms are presented for 5?+'s thermal decay, both of which invoke nitrosoalkane monomer 5m as an intermediate. In a related study, oxidation of nitrosoalkane 2m is found to mediate its facile denitrosation. This work affords the first examples of electron-transfer-mediated C,N bond cleavage of azodioxides and of nitrosoalkanes. Substantial bond weakening is shown to accompany electron loss from these substrates. For 5, π oxidation leads ultimately to σ C,N bond activation.
- Greer, Melinda L.,Sarker, Haripada,Mendicino, Maria E.,Blackstock, Silas C.
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- 1-Norbornyllithium as a precursor for the synthesis of novel organic 1-bicyclo[2.2.1]heptane derivatives and for the improved preparation of 1-chloro-bicyclo[2.2.2]octane
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An improved strategy for synthesis of 1-chloro-bicyclo[2.2.2]octane is described in which the key compounds 1-norbornyl substituted ethyl formate or 1-norbornylcarbaldehyde were prepared from 1-norbornyllithium. The latter appeared as a useful precursor for the synthesis of various organic bridgehead substituted derivatives.
- Kostova,Dimitrov
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- CARBOCYCLIC PROLINAMIDE DERIVATIVES
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This invention is directed to novel carbocyclic prolinamide derivatives of Formula (I), and pharmaceutically acceptable salts, solvates, solvates of the salt and prodrugs thereof, useful in the prevention (e.g., delaying the onset of or reducing the risk
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Paragraph 0202; 0203
(2018/04/11)
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- DERMATOLOGICAL COMPOSITIONS AND METHODS
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Disclosed are methods and compositions for regulating the melanin content of mammalian melanocytes; regulating pigmentation in mammalian skin, hair, wool or fur; treating or preventing various skin and proliferative disorders; by administration of various compounds, including alcohols, diols and/or triols and their analogues.
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- Treatment of neurodegenerative diseases
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Disclosed are methods for increasing the differentiation of mammalian neuronal cells for purposes of treating neurodegenerative diseases or nerve damage by administration of various compounds including alcohols, diols and/or triols and their analogues.
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- Treatment of diseases mediated by the nitric oxide/cGMP/protein kinase G pathway
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Disclosed are methods and compositions for stimulating cellular nitric oxide (NO) synthesis, cyclic guanosine monophosphate levels (cGMP), and protein kinase G (PKG) activity for purposes of treating diseases mediated by deficiencies in the NO/cGMP/PKG signal transduction pathway, by administration of various compounds including alcohols, diols and/or triols and their analogues.
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- Bicyclonon-1-ene: Matrix Isolation and Spectroscopic Characterization of a Moderately Strained Bridgehead Olefin
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Bicyclonon-1-ene was generated in low-temperature matrices and in fluid solutions by photodecomposition of bicyclooct-1-yldiazomethane and its photorearrangement product, 3-(bicyclooct-1-yl)diazirine.It was characterized by IR and UV absorption and by 1H and 13C NMR spectroscopy.Further evidence for the proposed structure was provided by self-trapping and by the spectral effects of deuteration on the olefinic carbon.Observed IR spectra and isotopic shifts agree well with the results of semiempirical (MNDO) and ab initio (SCF/6-31G*) calculations.
- Gudipati, Murthy S.,Radziszewski, Juliusz G.,Kaszynski, Piotr,Michl, Josef
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p. 3668 - 3674
(2007/10/02)
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- cis-Diazenes. Pressure Effects on Their Thermal Deazatization and Isomerization Reactions
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Effects of pressure on solution-phase rates of overall thermal decomposition, deazatization, and isomerization of several symmetric cis-diazenes (cis-azoalkanes) have been determined in hexane and in ethanol.Increasing pressure decreases all the rates.The large positive activation volumes for deazatization (e.g., +16 to +22 cm3/mol) have been interpreted in terms of a one-bond scission mechanism and an intermediate diazenyl radical.The smaller positive activation volumes for isomerization (e.g., +5 to +7 cm3/mol) are consistent with a nonradical inversion mechanism.Dramatic differences in rates between polar and nonpolar solvents are consistent with these mechanisms.
- Neuman, Robert C.,Berge, Charles T.,Binegar, Glen Al.,Adam, Waldemar,Nishizawa, Yoshinori
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p. 4564 - 4568
(2007/10/02)
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- cis-Diazenes. Viscosity Effects, One-Bond Scission, and Cis-Trans Isomerization
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Effects of solvent viscosity on the rates of overall thermal decomposition, deazatization, and iomerization of several symmetric and unsymmetric cis-diazenes (cis-azoalkanes) have been determined in pure alkanes and mixtures of octane and mineral oil.Increasing viscosity decreases the overall decomposition and deazatization rates for all of these cis-diazenes.While isomerization rates also decrease with increasing viscosity for most of the diazenes, that for cis-N-tert-butyl-N'-1-norbornyldiazene (1) increases.These results are interpreted in terms of deazatization via one-bond scission and an intermediate diazenyl radical, isomerization via nonradical inversion, and the possibility of isomerization via a diazenyl radical for 1.
- Neuman, Robert C.,Grow, Richard H.,Binegar, Glen A.,Gunderson, Howard J.
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p. 2682 - 2688
(2007/10/02)
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- Interpretation of the Reactivity of Benzyl Free Radical towards Peroxyacids in Terms of Orbital Interactions. Competition between Energy Gap Control and Overlap Control
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The factors which control the reactivity of alkyl free radicals R. in reaction (i) are studied.The reactivity of R. in (i) depends on the key orbital interaction between the SOMO of the radical and the LUMO of the peroxyacid.This interaction involves two contributions: (i) the energy gap SOMO-LUMO and (ii) the overlap SOMO-LUMO.In reaction (i) the main factor is overlap control which depends on spin delocalisation in the radical R..This proves that reaction (i) does not involve electron transfer.The energy gap control, which depends on the nucleophilic character of R., is only observed when the first factor is constant along a series of R..
- Fossey, Jacques,Lefort, Daniel,Massoudi, Massoud,Nedelec, Jean-Yves,Sorba, Jeanine
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p. 781 - 786
(2007/10/02)
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- Decarboxylation of Bridgehead Carboxylic Acids by the Barton Procedure
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Reductive decarboxylation of a series of bicyclic and polycyclic acids in which the carboxyl group is attached to the bridgehead position has been investigated.Conversion of the acids into thiohydroxamic esters occurs via reaction of the derived acid chlorides with N-hydroxypyridine-2-thione.Decomposition of the esters proceeds smoothly in boiling benzene in the presence of 1-butyl mercaptan to give the reduced product in high yield.The procedure appears to be generally applicable, and is unaffected by functional groups such as esters and acetals.
- Della, Ernest W.,Tsanaktsidis, John
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p. 2061 - 2066
(2007/10/02)
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- ETUDE DU CARACTERE NUCLEOPHILE DES RADICAUX LORS DE LA REACTION DE TRANSFERT SUR LA LIAISON O-O DES PERACIDES
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Peracids RCO3H yield free radicals R. which react either with the peracid or with solvent giving the alcohol ROH and the hydrocarbon RH.The nucleophilic character of the free radicals was modified either by substitution of the carbon bearing the odd electron by inductive groups or by changing the free radical hybridation by the means of blocked structures such as cyclic or bicyclic free radicals.For each R., the measurement of the ratio ROH/RH establishes a reactivity scale for R. with the peracid O-O bond.This reactivity does not depend on free radical stability but depends strongly on nucleophilic character.A primary free radical is less reactive than a secondary one, and is much less reactive than a tertiary one.A bridgehead free radical as the bicycloheptyle-1 does not react with the peracid.These results are interpreted to indicate a transition state with charge transfer (polar effect), the peracid being electrophilic and the free radical nucleophilic; PMO theory is discussed.
- Fossey, Jacques,Lefort, Daniel
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p. 1023 - 1036
(2007/10/02)
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