- Catalyst-Controlled Selective Functionalization of Unactivated C-H Bonds in the Presence of Electronically Activated C-H Bonds
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A new chiral dirhodium tetracarboxylate catalyst, Rh2(S-2-Cl-5-BrTPCP)4, has been developed for C-H functionalization reactions by means of donor/acceptor carbene intermediates. The dirhodium catalyst contains four (S)-1-(2-chloro-5-bromophenyl)-2,2-diphenylcyclopropane-1-carboxylate ligands, in which all four 2-chloro-5-bromophenyl groups are on the same face of the catalyst, leading to a structure, which is close to C4 symmetric. The catalyst induces highly site selective functionalization of remote, unactivated methylene C-H bonds even in the presence of electronically activated benzylic C-H bonds, which are typically favored using earlier established dirhodium catalysts, and the reactions proceed with high levels of diastereo- and enantioselectivity. This C-H functionalization method is applicable to a variety of aryl and heteroaryl derivatives. Furthermore, the potential of this methodology was illustrated by sequential C-H functionalization reactions to access the macrocyclic core of the cylindrocyclophane class of natural products.
- Liu, Wenbin,Ren, Zhi,Bosse, Aaron T.,Liao, Kuangbiao,Goldstein, Elizabeth L.,Bacsa, John,Musaev, Djamaladdin G.,Stoltz, Brian M.,Davies, Huw M. L.
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supporting information
p. 12247 - 12255
(2018/09/27)
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- Nickel-Catalyzed C-O Bond-Cleaving Alkylation of Esters: Direct Replacement of the Ester Moiety by Functionalized Alkyl Chains
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Two efficient protocols for the nickel-catalyzed aryl-alkyl cross-coupling reactions using esters as coupling components have been established. The methods enable the selective oxidative addition of nickel to acyl C-O and aryl C-O bonds and allow the aryl-alkyl cross-coupling via decarbonylative bond cleavage or through cleavage of a C-O bond with high efficiency and good functional group compatibility. The protocols allow the streamlined, unconventional utilization of widespread ester groups and their precursors, carboxylic acids and phenols, in synthetic organic chemistry.
- Liu, Xiangqian,Jia, Jiaqi,Rueping, Magnus
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p. 4491 - 4496
(2017/07/24)
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- Synthesis and evaluation of some substituted heterocyclic fluconazole analogues as antifungal agents
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A new series of fluconazole analogues of 1-(1H-1,2,4-triazol-1-yl)-2-(2,4- difluoro-phenyl)-3-4-(substituted-heterocyclic ring-1H-1,2,3- triazol-1-yl)-2-propanols (1-10) were designed, synthesized and evaluated as antifungal agents. Preliminary antifungal tests showed that most of the title compounds exhibited moderate activity with broad spectrum against eight human pathogenic fungi in vitro, compounds 1 and 6 had the best antifungal activity against Candida albicans with the value of MIC80 = 0.5 μg/mL respectively.
- Wang, Shudong,Zhang, Lei,Jin, Yongsheng,Tang, Jin Hao,Su, Hua,Yu, Shichong,Ren, Haixiang
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p. 2362 - 2364
(2014/06/09)
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- PIFA-mediated esterification reaction of alkynes with alcohols via oxidative cleavage of carbon triple bonds
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A metal-free esterification of alkynes via C≡C triple bond cleavage has been developed. In the presence of phenyliodine bis(trifluoroacetate), a diverse range of alkyne and alcohol substrates undergoes triple bond cleavage to produce carboxylic ester motifs in moderate to good yields. The transformation is proposed to proceed via hydroxyethanones and ethanediones as intermediates on the basis of mechanistic studies and exhibits a broad substrate scope and good functional group tolerance.
- Jiang, Qing,Zhao, An,Xu, Bin,Jia, Jing,Liu, Xin,Guo, Cancheng
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p. 2709 - 2715
(2014/04/17)
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- Role of the CAI-1 fatty acid tail in the Vibrio cholerae quorum sensing response
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Quorum sensing is a mechanism of chemical communication among bacteria that enables collective behaviors. In V. cholerae, the etiological agent of the disease cholera, quorum sensing controls group behaviors including virulence factor production and biofilm formation. The major V. cholerae quorum-sensing system consists of the extracellular signal molecule called CAI-1 and its cognate membrane bound receptor called CqsS. Here, the ligand binding activity of CqsS is probed with structural analogues of the natural signal. Enabled by our discovery of a structurally simplified analogue of CAI-1, we prepared and analyzed a focused library. The molecules were designed to probe the effects of conformational and structural changes along the length of the fatty acid tail of CAI-1. Our results, combined with pharmacophore modeling, suggest a molecular basis for signal molecule recognition and receptor fidelity with respect to the fatty acid tail portion of CAI-1. These efforts provide novel probes to enhance discovery of antivirulence agents for the treatment of V. cholerae.
- Perez, Lark J.,Ng, Wai-Leung,Marano, Paul,Brook, Karolina,Bassler, Bonnie L.,Semmelhack, Martin F.
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p. 9669 - 9681
(2013/01/16)
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- Convenient synthesis of arylpropargyl aldehydes and 4-aryl-3-butyn-2-ones from arylacetylenes and amide acetals
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The reaction of arylacetylenes 1 and N,N-dimethylformamide dimethylacetal (2a, DMF-DMA) afforded the corresponding arylpropargyl aldehydes 3 in moderate yields. Similarly, the reaction of 1 and N,N-dimethylacetamide dimethylacetal (2b, DMA-DMA) gave 4-aryl-3-butyn-2-ones 4.
- Lee, Ka Young,Lee, Mi Jung,GowriSankar, Saravanan,Kim, Jae Nyoung
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p. 5043 - 5046
(2007/10/03)
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