- Palladium-Catalyzed ortho-C-H Glycosylation/ ipso-Alkenylation of Aryl Iodides
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This report describes the first example of palladium-catalyzed ortho-C-H glycosylation/ipso-alkenylation of aryl iodides, and the easily accessible glycosyl chlorides are used as a glycosylation reagent. The reaction is compatible with the functional groups of the substrates, and a series of C-aryl glycosides have been synthesized in good to excellent yield and with excellent diastereoselectivity. It is found that a cheap 5-norbornene-2-carbonitrile as a transient mediator can effectively promote this reaction. In addition, ipso-arylation and cyanation were also realized by the strategy.
- Ding, Ya-Nan,Shi, Wei-Yu,Liu, Ce,Zheng, Nian,Li, Ming,An, Yang,Zhang, Zhe,Wang, Cui-Tian,Zhang, Bo-Sheng,Liang, Yong-Min
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p. 11280 - 11296
(2020/10/12)
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- Rapid Entry into Biologically Relevant α,α-Difluoroalkylphosphonates Bearing Allyl Protection-Deblocking under Ru(II)/(IV)-Catalysis
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A convenient synthetic route to α,α-difluoroalkylphosphonates is described. Structurally diverse aldehydes are condensed with LiF2CP(O)(OCH2CH-CH2)2. The resultant alcohols are captured as the pentafluorophenyl thionocarbonates and efficiently deoxygenated with HSnBu3, BEt3, and O2, and then smoothly deblocked with CpRu(IV)(π-allyl)quinoline-2-carboxylate (1-2 mol %) in methanol as an allyl cation scavenger. These mild deprotection conditions provide access to free α,α-difluoroalkylphosphonates in nearly quantitative yield. This methodology is used to rapidly construct new bis-α,α-difluoroalkyl phosphonate inhibitors of PTPIB (protein phosphotyrosine phosphatase-1B).
- Panigrahi, Kaushik,Fei, Xiang,Kitamura, Masato,Berkowitz, David B.
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supporting information
p. 9846 - 9851
(2019/12/24)
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- Mannose-binding geometry of pradimicin A
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Pradimicins (PRMs) and benanomicins are the only family of non-peptidic natural products with lectin-like properties, that is, they recognize D-mannopyranoside (Man) in the presence of Ca2+ ions. Coupled with their unique Man binding ability, t
- Nakagawa, Yu,Doi, Takashi,Taketani, Takara,Takegoshi,Igarashi, Yasuhiro,Ito, Yukishige
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supporting information
p. 10516 - 10525
(2013/08/23)
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- Analysis of the binding specificities of oligomannoside-binding proteins using methylated monosaccharides
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The binding specificities of the closely related lectins from Canavalia ensiformis and Dioclea grandiflora were examined using specifically O-alkylated mono- and disaccharides. Both lectins accept any substitution at the monosaccharide C2 hydroxyl group. The binding energy of C2-alkylated ligands-concanavalin A complexes increases by 1 kcal mol-1 for the C2-O-ethyl ligand, while the binding energies of the corresponding complexes with the Dioclea lectin are identical. Both lectins accept methyl, but not ethyl, substitution of the C3 hydroxyl, in contrast to earlier reports. The results are interpreted in terms of existing models of the concanavalin A binding site. While the results are consistent with a model of the concanavalin A extended binding site that places the non-reducing terminus of all disaccharides in the monosaccharide binding site, they point to the dangers of interpreting the binding behavior of unnatural saccharide ligands on the basis of crystallographic data obtained with native ligands.
- Chervenak, Mary C.,Toone, Eric J.
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p. 1963 - 1977
(2007/10/03)
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