- B(C6F5)3-Catalyzed Hydrosilylation of Vinylcyclopropanes
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A hydrosilylation of vinylcyclopropanes (VCPs) catalyzed by the strong boron Lewis acid B(C6F5)3 is reported. For the majority of VCPs, little or no ring opening of the cyclopropyl unit is observed. Conversely, for VCPs with bulky R groups, such as ortho-substituted aryl rings or branched alkyl residues, ring opening is the exclusive reaction pathway. This finding is explained by the thwarted hydride delivery to a sterically shielded, β-silicon-stabilized cyclopropylcarbinyl cation intermediate.
- He, Tao,Long, Peng-Wei,Oestreich, Martin
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supporting information
p. 7383 - 7386
(2020/10/12)
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- Br?nsted acid mediated intramolecular cyclopropane ring expansion/[4 + 2]-cycloaddition
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A cascade reaction of 3-hydroxy-2-phenylisoindolin-1-one and cyclopropyl ketone has been developed via a Br?nsted acid-promoted ring-opening/intramolecular cross-cycloaddition/[4 + 2]-cycloaddition process. The developed methodology provides straightforward access to pentacyclic isoindolin-1-one derivatives under simple reaction conditions.
- Li, Jian,Zhu, Shangrong,Xu, Qiuneng,Liu, Li,Yan, Shenghu
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p. 10004 - 10008
(2019/12/23)
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- Continuous flow synthesis of ketones from carbon dioxide and organolithium or grignard reagents
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We describe an efficient continuous flow synthesis of ketones from CO 2 and organolithium or Grignard reagents that exhibits significant advantages over conventional batch conditions in suppressing undesired symmetric ketone and tertiary alcohol byproducts. We observed an unprecedented solvent-dependence of the organolithium reactivity, the key factor in governing selectivity during the flow process. A facile, telescoped three-step-one-flow process for the preparation of ketones in a modular fashion through the in-line generation of organometallic reagents is also established.
- Wu, Jie,Yang, Xiaoqing,He, Zhi,Mao, Xianwen,Hatton, T. Alan,Jamison, Timothy F.
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supporting information
p. 8416 - 8420
(2014/08/18)
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- α-Methylation at benzylic fragment of N-aryl-N′-benzyl ureas provides TRPV1 antagonists with better pharmacokinetic properties and higher efficacy in inflammatory pain model
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SAR studies for N-aryl-N′-benzyl urea class of TRPV1 antagonists have been extended to cover α-benzyl alkylation. Alkylated compounds showed weaker in vitro potencies in blocking capsaicin activation of TRPV1 receptor, but possessed improved pharmacokinetic properties. Further structural manipulations that included replacement of isoquinoline core with indazole and isolation of single enantiomer led to TRPV1 antagonists like (R)-16a with superior pharmacokinetic properties and greater potency in animal model of inflammatory pain.
- Gomtsyan, Arthur,Bayburt, Erol K.,Keddy, Ryan,Turner, Sean C.,Jinkerson, Tammie K.,Didomenico, Stanley,Perner, Richard J.,Koenig, John R.,Drizin, Irene,McDonald, Heath A.,Surowy, Carol S.,Honore, Prisca,Mikusa, Joe,Marsh, Kennan C.,Wetter, Jill M.,Faltynek, Connie R.,Lee, Chih-Hung
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p. 3894 - 3899
(2008/02/09)
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- DFT evidence for a stepwise mechanism in the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals
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(Chemical Equation Presented) Hybrid DFT calculations of the potential energy surface (PES) relative to the O-neophyl rearrangement of a series of ring-substituted 1,1-diarylalkoxyl radicals have been carried out at the UB3LYP/6-31G(d) level of theory. On the basis of the computational data, the rearrangement can be described as a consecutive reaction of the type a ? b → c (see above graphic), and the steady-state approximation could be applied in all cases to the intermediate b. The first-order rearrangement rate constants [kobs = k1k2/(k-1 + k 2)] were thus obtained from the computed activation free-energies and were compared with the experimental rate constants measured previously in MeCN solution by laser flash photolysis. An excellent agreement is observed along the two series, which strongly supports the hypothesis that the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals proceeds through the formation of the reactive 1-oxaspiro [2,5]octadienyl radical intermediate. This is in contrast to previous hypotheses that involve either a long-lived intermediate or the absence of this intermediate along the reaction path. The calculated rearrangement free-energies decrease upon going from the methoxy-substituted radical (ΔG° = -16.4 kcal·mol-1) to the nitro-substituted one (ΔG° = -21.8 kcal·mol-1), which follows a trend that is similar to the one observed for the C Ar-O bond dissociation enthalpies (BDEs) of ring-substituted anisoles. This evidence indicates that in the O-neophyl rearrangement the effect of ring substituents on the strength of the newly formed CAr-O bond plays an important role.
- Bietti, Massimo,Ercolani, Gianfranco,Salamone, Michela
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p. 4515 - 4519
(2008/02/05)
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- The effect of ring substitution on the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals. A product and time-resolved kinetic study
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A product and time-resolved kinetic study of the effect of ring substitution on the reactivity of 1,1-diarylalkoxyl radicals has been carried out. The radicals undergo an O-neophyl shift to give the isomeric 1-aryl-1-aryloxyalkyl radicals from which the corresponding aromatic ketones are formed. The rearrangement rate constants are influenced by ring substitution, increasing in the presence of electron-withdrawing substituents and decreasing in the presence of electron-donating ones. From the results of product and kinetic studies, the following migratory aptitudes have been obtained: 4-trifluoromethylphenyl > phenyl ? 4-methylphenyl > 4-methoxyphenyl. Excellent Hammett-type correlations between the σ+ substituent constants and both the visible absorption band maxima and the rearrangement rate constants have been obtained. The experimental results indicate that the rearrangement is governed by electronic effects in the starting 1,1-diarylalkoxyl radicals, whereas the stability of the rearranged carbon-centered radical plays a minor role, in line with a reactant-like transition state, strongly supporting the hypothesis that the O-neophyl rearrangement of 1,1-diarylalkoxyl radicals proceeds through a concerted mechanism.
- Aureliano Antunes, Carla S.,Bietti, Massimo,Ercolani, Gianfranco,Lanzalunga, Osvaldo,Salamone, Michela
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p. 3884 - 3891
(2007/10/03)
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- Fused azabicyclic compounds that inhibit vanilloid receptor subtype 1 (VR1) receptor
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Compounds of formula (I) are novel VR1 antagonists that are useful in treating pain, inflammatory thermal hyperalgesia, urinary incontinence and bladder overactivity, wherein X1, X2, X3, X4, X5, R5, R6, R7, R8a, R8b, R9, Z1, Z2 and L are as defined in the description.
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- Fused azabicyclic compounds that inhibit vanilloid receptor subtype 1 (VR1) receptor
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Compounds of formula (I) are novel VR1 antagonists that are useful in treating pain, inflammatory thermal hyperalgesia, urinary incontinence and bladder overactivity.
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Page/Page column 43
(2010/02/11)
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- Fused azabicyclic compounds that inhibit vanilloid receptor subtype 1 (VR1) receptor
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Compounds of formula (I) are novel VR1 antagonists that are useful in treating pain, inflammatory thermal hyperalgesia, urinary incontinence and bladder overactivity.
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- 1,4-diaryl-1-cyclopropyl-4-substituted butanes as insecticides and acaricides
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The 1,4-diaryl-1-cyclopropyl-4-substituted butane pesticides of the following formula are effective as insecticides and acaricides: STR1 in which X and Y are independently hydrogen, halogen, alkyl, alkoxy, cycloalkylalkoxy, alkylcarbonyl, alkoxycarbonyl,
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- Insecticidal cyclopropyl-substituted di(aryl) compounds
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Compounds of the formula STR1 in which Ar is substituted or unsubstituted phenyl, naphthyl, or thienyl; Z is oxygen, sulfur, or methylene; and Ar' is 2-methyl[1,1'-biphenyl]-3-yl, 3-phenoxyphenyl, 4-fluoro-3-phenoxyphenyl, or 6-phenoxy-2-pyridyl exhibit pyrethroid-like insecticidal and acaricidal activity and are relatively harmless to aquatic fauna.
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