- Ambident Reactivity of Phenolate Anions Revisited: A Quantitative Approach to Phenolate Reactivities
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Prompted by the observation that the regioselectivities of phenolate reactions (C versus O attack) are opposite to the predictions by the principle of hard and soft acids and bases, we performed a comprehensive experimental and computational investigation of phenolate reactivities. Rate and equilibrium constants for the reactions of various phenolate ions with benzhydrylium ions (Aryl2CH+) and structurally related quinone methides have been determined photometrically in polar aprotic solvents. Quantum chemical calculations at the SMD(MeCN)/M06-2X/6-31+G(d,p) level confirmed that O attack is generally favored under kinetically controlled conditions, whereas C attack is favored under thermodynamically controlled conditions. Exceptions are diffusion-limited reactions with strong electrophiles, which give mixtures of products arising from O and C attack, as well as reactions with metal alkoxides in nonpolar solvents, where oxygen attack is blocked by strong ion pairing. The Lewis basicity (LB) and nucleophilicity (N, sN) parameters of phenolates determined in this work can be used to predict whether their reactions with electrophiles are kinetically or thermodynamically controlled and whether the rates are activation- or diffusion-limited. Comparison of the measured rate constants for the reactions of phenolates with carbocations with the Gibbs energies for single-electron transfer manifests that these reactions proceed via polar mechanisms.
- Mayer, Robert J.,Breugst, Martin,Hampel, Nathalie,Ofial, Armin R.,Mayr, Herbert
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p. 8837 - 8858
(2019/07/08)
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- Novel substituted [1,4] benzodioxino[2,3-e] isoindole derivatives, method for preparing and pharmaceutical compositions containing same
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Compounds of formula (I): wherein: A is as defined in the description, Y represents a group selected from an oxygen atom and a methylene group, R2 represents a hydrogen atom and in that case: R3 represents a group selected from a hydrogen atom and the groups linear or branched (C1-C6)alkyl, aryl, aryl-(C1-C6)alkyl (in which the alkyl moiety is linear or branched) and SO2CF3, or R2 and R3 form a bond, R1 represents a group selected from a hydrogen atom and the groups linear or branched (C1-C6)alkyl, aryl and aryl-(C1-C6)alkyl (in which the alkyl moiety is linear or branched) or a linear or branched (C1-C6)alkylene chain, Z1 and Z2 each represent a hydrogen atom or Z1 and Z2, together with the carbon atoms carrying them, form a phenyl group. Medicaments.
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Page/Page column 12-13
(2010/10/19)
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- Therapeutic diphenyl ether ligands
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This invention is directed to compounds of formula Ia, Ib or Ic and to pharmaceutical compositions thereof: or a prodrug thereof and a pharmaceutically acceptable carrier, wherein the R groups are defined in the specification; and, in which the dashed line represents an optional double bond. The invention is also directed to methods of treating, diagnosing, and preventing disorders of the central nervous system that are associated with 5HT receptors, including obesity, attention deficit disorder, migraine, depression, epilepsy, anxiety, Alzheimer's disease, withdrawal from drug abuse, pain, schizophrenia, stress-related disorders, panic disorder, sleep disorders, phobias, obsessive compulsive disorder, post-traumatic-stress syndrome, immune system depression, stress-induced gastrointestinal dysfunction, stress-induced cardiovascular dysfunction, and sexual dysfunction.
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Page/Page column 36
(2010/10/20)
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- Benzocarbapenems from indoles
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The 8,8a-dihydroazeto[1,2-a]indol-2(1H)-ones (benzocarbapenems) 1a, 16, 17, 22, 27, 35 and 36 have been prepared by cyclodehydration of the corresponding β-amino acids, these amino acids being obtained by reduction of the analogous 2-substituted or 2,7-disubstituted indoles. The hydroxy group of compound 36 is designed to mimic the carboxylic acid function of the carbapenems on the basis of molecular modelling. The azetidinones 1a and 27, which are unsubstituted at the methylene group of the four-membered ring, are unstable and highly susceptible to ring opening by nucleophiles but the compounds 22,35 and 36 with two methyl substituents at this position are much more stable. The carbonyl stretching frequency in the IR is close to 1770 cm-1 for all the azetidinones except the phenol 36 for which the absorption is at 1735 cm-1. An X-ray crystal structure of compound 36 is reported.
- Coulton, Steven,Gilchrist, Thomas L.,Graham, Keith
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p. 1193 - 1202
(2007/10/03)
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- The synthesis of 7-alkoxyindoles
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A number of protected 7-hydroxyindoles was prepared by reaction of the protected 2-nitrophenols with vinylmagnesium bromide. Benzhydryl was shown to be the protecting group of choice, giving good yields of the indole and being readily removed for subsequent transformations of the 7-hydroxy function.
- Dobson,Todd,Gilmore
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p. 611 - 617
(2007/10/02)
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