- Functionalization of the Methyl Group of 1,4-Dimethyl-1,4-dihydronaphthalene-1,4-endoperoxide
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The acid-catalysed cleavage of 1,4-dimethyl-1,4-dihydronaphthalene-1,4-endoperoxide gives the 4-hydroxy, methoxy, trifluoroacetoxy, formyloxy, bromo, and chloro methyl derivatives of 1-methylnaphthalene in yields of 36, 38, 52, 76, 77, and 100percent respectively when water, methanol, trifluoroacetic, formic, hydrobromic, or hydrochloric acids are used as reagents.
- Jefford, Charles W.,Rossier, Jean-Claude,Kohmoto, Shigeo,Boukouvalas, John
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- Anticoagulant activity of singlet oxygen released from a water soluble endoperoxide by thermal cycloreversion
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Singlet oxygen generated by photosensitization has limited potential in vivo due to light attenuation in tissues. However, controlled chemical generation of this reactive oxygen species is likely to open new therapeutic spaces to explore. The fact that its activity is limited by the rate of cycloreversion reaction and the diffusion distance of the excited state molecular oxygen species, is a clear advantage, considering the serious side effects of off-target anticoagulants. In this work, we present novel 1,4-naphthalene endoperoxides as potential anti-coagulant agents due to thermal release of singlet oxygen. This journal is
- Liu, Meina,Ucar, Esma,Liu, Ziang,Wang, Lei,Yang, Li,Xu, Jiawei,Wang, Lei
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- Intramolecular photocycloaddition reactions of 2- and 4-(5-arylpent-4-enyl)-1-cyanonaphthalenes
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Photoreactions of 1-cyanonaphthalene derivatives containing 5-arylpent-4-enyl groups at C-2 or C-4 of the naphthalene ring were investigated. Photoreactions of C-2 derivatives in benzene or CH3CN generated intramolecular [2 + 2] and [3 + 2] photocycloadducts. Substances bearing electron-rich and electron-poor phenyl groups produced respective [2 + 2] and [3 + 2] photocycloadducts preferentially. In contrast, photoreactions of C-4 linked 1-cyanonaphthalenes produced intramolecular [4 + 2] photocycloadducts as main products along with stereoisomers of tricyclic compounds as minor products. The formation of [4 + 2] photocycloadducts was promoted by using benzophenone or Michler's ketone triplet photosensitization, and quenched by O2 or ferrocene. Intramolecular singlet exciplexes, which serve as important intermediates in the mechanistic pathways for these reactions, governed the site-selectivities in photoreactions of both of the 2- and 4-(5-arylpent-4-enyl)-1-cyanonaphthalenes. In addition, [4 + 2] photocycloadducts were observed to undergo di-π-methane rearrangement under irradiation conditions to produce angular triquinane derivatives.
- Maeda, Hajime,Enya, Kouhei,Negoro, Naoki,Mizuno, Kazuhiko
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p. 173 - 184
(2019/02/15)
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- Resonance energy of diradicals - 1,8-naphthoquinodimethane
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From the racemization of 19c and the temperature and NO dependence of the trapping rate of 20b between 218 and 288°C the energy profile for the equilibrium 19b ? 20b is derived. The singlet-triplet splitting of the diradical is 2.5 kcal · mol-1 with the triplet being the ground state. By comparison of the experimental reaction enthalpy with the analogous value for 25, 26 or a hypothetical model reaction with non-interacting radicals it is shown that the stabilizing interaction of the radicals in the singlet state of 20b is negligible making the stabilization of the triplet equivalent to the singlet-triplet splitting. By using literature data it is shown by an analogous analysis that the interaction of the radicals in the bisallyl diradical 28 and in the triplet state of the trimethylenmethane derivative 29 is also negligible whereas in the singlet state of 29 the interaction is strongly destabilizing. VCH Verlagsgesellschaft mbH, 1996.
- Roth, Wolfgang R.,Unger, Christian,Wasser, Thorsten
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p. 2155 - 2169
(2007/10/03)
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- Photobromination of Side-Chain Methyl Groups on Arenes with N-Bromosuccinimide - Convenient and Selective Syntheses of Bis(bromomethyl)- and (Bromomethyl)methylarenes -
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Photobromination of side-chain methyl groups on arenes with N-bromosuccinimide (NBS) was investigated.Visible light irradiation in benzene solvent was extremely effective in increasing the selectivity of the reaction and the efficiency for product purification.The photobromination of 1,4-, 1,8, 2,3-, and 2,6-dimethylnaphthalenes, 4,4'-dimethylbiphenyl, and p-xylene with 2.2 mol equivalents of NBS quantitatively afforded the corresponding bis(bromomethyl)arenes, respectively.The (bromomethyl)methylarenes were also obtained in good yields in the photobromination reactions of the above dimethylarenes with 1.1 mol equivalents of NBS.
- Futamura, Shigeru,Zong, Zhi-Min
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p. 345 - 348
(2007/10/02)
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- 187. Acid-Catalyzed Cleavage of 1,4-Dimethyl-1,4-dihydronaphthalene 1,4-Endoperoxide. Reactivity of the Resulting Hydroxyperoxy Carbocation with Nucleophiles
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In the presence of acids, 1,4-dimethyl-1,4-dihydronaphthalene 1,4-endoperoxie readily reacts with nucleophiles to produce methyl- and ring-substituted naphthalenes in high yields.The regioselectivity observed depends on the nucleophile.The key intermediate is shown to be the corresponding hydroperoxy carbocation which could be intercepted in certain cases prior to aromatization.The hydroperoxide also undergoes Hock-type cleavage and dimerization giving 2,3-dihydro-1-benzoxepins, 4-methyl-1-naphthol, and 1,2,5,6-tetraoxocane as by-products.
- Jefford, Charles W.,Rossier, Jean-Claud,Kohmoto, Shigeo,Boukouvalas, John
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p. 1804 - 1814
(2007/10/02)
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- Preparation of a series of substituted fluoromethylnaphthalenes
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A series of 22 3- and 4-substituted 1-fluoromethylnaphthalenes have been synthesized.Details of practical procedures for the preparation of all intermediates are described, and physical properties for all of the substituted naphthalenes synthesized, and spectral parameters for 51 previously unknown compounds, are given.
- Dixon, Elisabeth A.,Fischer, Alfred,Robinson, Frank P.
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p. 2629 - 2641
(2007/10/02)
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