- Pd-Catalyzed ipso, meta-Dimethylation of ortho-Substituted Iodoarenes via a Base-Controlled C-H Activation Cascade with Dimethyl Carbonate as the Methyl Source
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A methyl group can have a profound impact on the pharmacological properties of organic molecules. Hence, developing methylation methods and methylating reagents is essential in medicinal chemistry. We report a palladium-catalyzed dimethylation reaction of ortho-substituted iodoarenes using dimethyl carbonate as a methyl source. In the presence of K2CO3 as a base, iodoarenes are dimethylated at the ipso- and meta-positions of the iodo group, which represents a novel strategy for meta-C-H methylation. With KOAc as the base, subsequent oxidative C(sp3)-H/C(sp3)-H coupling occurs; in this case, the overall transformation achieves triple C-H activation to form three new C-C bonds. These reactions allow expedient access to 2,6-dimethylated phenols, 2,3-dihydrobenzofurans, and indanes, which are ubiquitous structural motifs and essential synthetic intermediates of biologically and pharmacologically active compounds.
- Wu, Zhuo,Wei, Feng,Wan, Bin,Zhang, Yanghui
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p. 4524 - 4530
(2021/05/04)
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- Dual Ligand-Enabled Nondirected C-H Cyanation of Arenes
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Aromatic nitriles are key structural units in organic chemistry and, therefore, highly attractive targets for C-H activation. Herein, the development of an arene-limited, nondirected C-H cyanation based on the use of two cooperatively acting commercially available ligands is reported. The reaction enables the cyanation of arenes by C-H activation in the absence of directing groups and is therefore complementary to established approaches.
- Chen, Hao,Mondal, Arup,Wedi, Philipp,Van Gemmeren, Manuel
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p. 1979 - 1984
(2019/02/19)
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- Acetonitrile as a cyanating reagent: Cu-catalyzed cyanation of arenes
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A novel approach to the Cu-catalyzed cyanation of simple arenes using acetonitrile as an attractive cyano source has been documented. The C-H functionalization of arenes without directing groups involves a sequential iodination/cyanation to give the desired aromatic nitriles in good yields. A highly efficient Cu/TEMPO system for acetonitrile C-CN bond cleavage has been discovered. TEMPO is used as a cheap oxidant and enables the reaction to be catalytic in copper. Moreover, TEMPOCH2CN 6 has been identified as the active cyanating agent and shows high reactivity for forming the -CN moiety.
- Zhu, Yamin,Zhao, Mengdi,Lu, Wenkui,Li, Linyi,Shen, Zengming
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supporting information
p. 2602 - 2605
(2015/06/16)
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- NOVEL COMPOUNDS FOR TREATMENT OF NEURODEGENERATION ASSOCIATED WITH DISEASES, SUCH AS ALZHEIMER'S DISEASE OR DEMENTIA
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The present invention relates to novel compounds of formula (I) and their pharmaceutical compositions. In addition, the present invention relates to therapeutic methods for the treatment and/or prevention of Aβ-related pathologies such as Downs syndrome, β- amyloid angiopathy such as but not limited to cerebral amyloid angiopathy or hereditary cerebral hemorrhage, disorders associated with cognitive impairment such as but not limited to MCI ("mild cognitive impairment"), Alzheimer Disease, memory loss, attention deficit symptoms associated with Alzheimer disease, neurodegeneration associated with diseases such as Alzheimer disease or dementia including dementia of mixed vascular and degenerative origin, pre-senile dementia, senile dementia and dementia associated with Parkinson's disease, progressive supranuclear palsy or cortical basal degeneration.
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Page/Page column 74-75
(2011/02/24)
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- Seeking passe-partout in the catalytic asymmetric aziridination of imines: Evolving toward substrate generality for a single chemzyme
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The asymmetric catalytic aziridination reaction (AZ reaction) of imines derived from dianisylmethyl (DAM) amine and tetra-methyldianisylmethyl (MEDAM) amine were examined with boroxinate catalysts prepared from both the VANOL and VAPOL ligands. This included an evaluation of different protocols for the preparation of the catalyst. The AZ reaction of DAM and MEDAM imines prepared from nine different aryl and aliphatic aldehydes were examined. The MEDAM imines were superior to the DAM imines in the AZ reaction, giving much higher asymmetric inductions and higher overall yields of aziridines. The MEDAM imines were found to also be superior to the previously studied diphenylmethyl (benzhydryl or Bh) and tetra-tert-butyldianisylmethyl (BUDAM) imines especially for imines derived from aliphatic aldehydes. The average asymmetric induction over the nine different MEDAM imines studied was 97% ee with the VAPOL catalyst and 96% ee with the VANOL catalyst. The MEDAM imines can be deprotected to give N-H aziridines in all cases except for some electron-rich aryl aldehydes. The MEDAM imines are much more reactive than benzhydryl imines, and this was most evident when a diazoacetate ester is replaced by a diazoacetamide. The less reactive diazoacetamides give very low yields in their reactions with benzhydryl imines but high yields with MEDAM imines.
- Mukherjee, Munmun,Gupta, Anil K.,Lu, Zhenjie,Zhang, Yu,Wulff, William D.
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supporting information; experimental part
p. 5643 - 5660
(2010/11/18)
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- Mapping the active site in a chemzyme: Diversity in the N-substituent in the catalytic asymmetric aziridination of imines
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(Chemical Equation Presented) The active site of the aziridination catalyst derived from either the VANOL or VAPOL ligand and B(OPh)3 is larger than expected and can accommodate not only significant substitution on the diarylmethyl unit of the imine but also that alkyl (but not perfluorylalkyl) substituents on the aryl groups lead to enhanced rates and enantioselection. The screen of diarylmethyl N-substituents on the imine revealed that the 3,5-di-tert-butyldianisylmethyl group (BUDAM) gave exceptionally high asymmetric inductions for imines of aryl aldehydes.
- Zhang, Yu,Lu, Zhenjie,Desai, Aman,Wulff, William D.
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supporting information; experimental part
p. 5429 - 5432
(2009/06/20)
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- Antipicornavirus Activity of Tetrazole Analogues Related to Disoxaril
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A series of tetrazole analogues of Win 54954, a broad-spectrum antipicornavirus compound, has been synthesized to address the acid lability of the oxazoline ring of this series of compounds.The results of X-ray crystallography studies of several members o
- Diana, Guy D.,Cutcliffe, David,Volkots, Deborah L.,Mallamo, John P.,Bailey, Thomas R.,et al.
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p. 3240 - 3250
(2007/10/02)
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