293308-66-4Relevant academic research and scientific papers
FUSED-RING DERIVATIVE AND MEDICAL APPLICATION OF SAME
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Paragraph 0086, (2013/03/26)
The present invention provides compounds useful as agents for the prevention or treatment of a disease associated with abnormal plasma uric acid level and the like. The present invention relates to fused ring derivatives represented by the following formula (I) having xanthine oxidase inhibitory activities and useful as agents for the prevention or treatment of a disease associated with abnormality of plasma uric acid level, prodrugs thereof, salts thereof or the like. In the formula (I), X1 and X2 represent CH or N; ring U represents aryl or heteroaryl; m represents integral number from 0 to 2; n represents integral number from 0 to 3; R1 represents a hydroxy group, amino or C1-6 alkyl; R2 represents C1-6 alkyl, C1-6 alkoxy C1-6 alkyl or the like.
Acid-catalyzed dehydration of naphthalene-cis-1,2-dihydrodiols: Origin of impaired resonance effect of 3-substituents
Kudavalli, Jaya Satyanarayana,Boyd, Derek R.,Sharma, Narain D.,More O'Ferrall, Rory A.
supporting information; experimental part, p. 9338 - 9343 (2012/01/03)
Acid-catalyzed dehydrations of substituted naphthalene-cis-1,2-dihydrodiols occur with loss of the 1- or 2-OH group to form 2- and 1-naphthols, respectively. Effects of substituents MeO, Me, H, F, Br, I, and CN at 3-, 6-, and 7-positions of the naphthalene ring are consistent with rate-determining formation of β-hydroxynaphthalenium ion (carbocation) intermediates. For reaction of the 1-hydroxyl group the 3-substituents are correlated by the Yukawa-Tsuno relationship with ρ = -4.7 and r = 0.25 or by σp constants with ρ = -4.25; for reaction of the 2-hydroxyl group the 3-substituents are correlated by σm constants with ρ = -8.1. The correlations for the 1-hydroxyl imply a surprisingly weak resonance interaction of +M substituents (MeO, Me) with a carbocation reaction center but are consistent with the corresponding correlation for acid-catalyzed dehydration of 3-substituted benzene-cis-1,2-dihydrodiols for which ρ = -6.9 and r = 0.43. Substituents at the 6- and 7-positions of the naphthalene rings by contrast are correlated by σ+ with ρ = -3.2 for reaction of the 1-hydroxyl group and ρ = -2.7 for reaction of the 2-hydroxyl group. The unimpaired resonance implied by these substituent effects appears to be inconsistent with a previous explanation of the weak resonance of the 3-substituents in terms of imbalance of charge development and/or nonplanarity of the benzenium ring in the transition state. An alternative possibility is that the adjacent hydroxyl group interferes sterically with conjugation of +M substituents. "Hyperaromaticity" of the arenium ion intermediates does not appear to be a factor influencing this behavior.
