共查询到20条相似文献,搜索用时 0 毫秒
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Ivan A. Gagarinov Tiehai Li Na Wei Javier SastreTorao Robert P. deVries Margreet A. Wolfert Geert‐Jan Boons 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(31):10657-10662
We describe a chemoenzymatic strategy that can give a library of differentially fucosylated and sialylated oligosaccharides starting from a single chemically synthesized tri‐N‐acetyllactosamine derivative. The common precursor could easily be converted into 6 different hexasaccharides in which the glucosamine moieties are either acetylated (GlcNAc) or modified as a free amine (GlcNH2) or Boc (GlcNHBoc). Fucosylation of the resulting compounds by a recombinant fucosyl transferase resulted in only modification of the natural GlcNAc moieties, providing access to 6 selectively mono‐ and bis‐fucosylated oligosaccharides. Conversion of the GlcNH2 or GlcNHBoc moieties into the natural GlcNAc, followed by sialylation by sialyl transferases gave 12 differently fucosylated and sialylated compounds. The oligosaccharides were printed as a microarray that was probed by several glycan‐binding proteins, demonstrating that complex patterns of fucosylation can modulate glycan recognition. 相似文献
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Aijie Cai Arjan W. Kleij 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(42):15086-15091
We describe here the first general asymmetric synthesis of sterically encumbered α,α‐disubstituted allylic sulfones via Pd‐catalyzed allylic substitution. The design and application of a new and highly efficient phosphoramidite ligand ( L10 ) proved to be crucial, and a wide variety of challenging allylic sulfones featuring quaternary stereocenters could be obtained in good yields and with good to excellent levels of regio‐ and enantioselectivities under attractive process conditions. The developed methodology employs easily accessible chemical feedstock including racemic allylic precursors and sodium sulfinates. The utility of the method is further demonstrated by the synthesis of the sesquiterpene (?)‐Agelasidine A. 相似文献
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Dawei Chen Ridao Chen Ruishan Wang Jianhua Li Kebo Xie Chuancai Bian Lili Sun Xiaolin Zhang Jimei Liu Lin Yang Fei Ye Xiaoming Yu Jungui Dai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(43):12869-12873
The catalytic promiscuity of the novel benzophenone C‐glycosyltransferase, MiCGT, which is involved in the biosynthesis of mangiferin from Mangifera indica, was explored. MiCGT exhibited a robust capability to regio‐ and stereospecific C‐glycosylation of 35 structurally diverse druglike scaffolds and simple phenolics with UDP‐glucose, and also formed O‐ and N‐glycosides. Moreover, MiCGT was able to generate C‐xylosides with UDP‐xylose. The OGT‐reversibility of MiCGT was also exploited to generate C‐glucosides with simple sugar donor. Three aryl‐C‐glycosides exhibited potent SGLT2 inhibitory activities with IC50 values of 2.6×, 7.6×, and 7.6×10−7 M , respectively. These findings demonstrate for the first time the significant potential of an enzymatic approach to diversification through C‐glycosidation of bioactive natural and unnatural products in drug discovery. 相似文献
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Da Zhao Jiji Zhang Zuowei Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(47):13116-13120
o‐Carboryne can undergo α‐C H bond insertion with tertiary amines, thus affording α‐carboranylated amines in very good regioselectivity and isolated yields. In this process, the nucleophilic addition of tertiary amines to the multiple bond of o‐carboryne generates a zwitterionic intermediate. An intramolecular proton transfer, followed by a nucleophilic attack leads to the formation of the final product. Thus, regioselectivity is highly dependent upon the acidity of α‐C H proton of tertiary amines. This approach serves as an efficient methodology for the preparation of a series of 1‐aminoalkyl‐o‐carboranes. 相似文献
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Ruocheng Sang Stamatis E. Korkis Wanqi Su Fei Ye Pascal S. Engl Florian Berger Tobias Ritter 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16307-16312
Herein, we report a two‐step process forming arene C?O bonds in excellent site‐selectivity at a late‐stage. The C?O bond formation is achieved by selective introduction of a thianthrenium group, which is then converted into C?O bonds using photoredox chemistry. Electron‐rich, ‐poor and ‐neutral arenes as well as complex drug‐like small molecules are successfully transformed into both phenols and various ethers. The sequence differs conceptually from all previous arene oxygenation reactions in that oxygen functionality can be incorporated into complex small molecules at a late stage site‐selectively, which has not been shown via aryl halides. 相似文献
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The asymmetric formal hydroamination of enamines using a CuH catalyst is reported. The method provides a straightforward and efficient approach to the synthesis of chiral 1,2‐dialkyl amines in good yields with high levels of enantioselectivities for a broad range of substrates, and should have significant value for the preparation of molecules bearing a 1,2‐diamine motif. 相似文献
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Zhong‐Jian Cai Chen‐Xu Liu Qing Gu Chao Zheng Shu‐Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2171-2175
Asymmetric C?H bond functionalization reaction is one of the most efficient and straightforward methods for the synthesis of optically active molecules. Herein we disclose an asymmetric C?H/C?H cross‐coupling reaction of ferrocenes with azoles such as oxazoles and thiazoles. Palladium(II)/monoprotected amino acid (MPAA) catalytic system which exhibits excellent reactivity and regioselectivity for oxazoles and thiazoles. This method offers a powerful strategy for constructing planar chiral ferrocenes. Mechanistic studies suggest that the C?H bond cleavage of azoles is likely proceeding through a SEAr process and may not be a turnover limiting step. 相似文献
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Richard Y. Liu Yang Yang Stephen L. Buchwald 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(45):14283-14286
A copper‐catalyzed, chemoselective hydrometalation process enables the use of simple allenes as allylmetal nucleophile surrogates in imine allylation reactions. By modulating the nitrogen‐protecting group, either highly branched‐ or linear‐selective addition can be achieved from the same allene. Both reactions exhibit excellent diastereoselectivity and broad functional‐group tolerance. Preliminary results indicate that good enantioselectivity can also be achieved in the linear‐selective reaction. Finally, a mechanistic model for the regiodivergence is proposed on the basis of density functional theory calculations. 相似文献
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Regio‐ and Enantio‐selective Chemo‐enzymatic C−H‐Lactonization of Decanoic Acid to (S)‐δ‐Decalactone
Jack Manning Michele Tavanti Joanne L. Porter Nico Kress Sam P. DeVisser Nicholas J. Turner Sabine L. Flitsch 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(17):5724-5727
The conversion of saturated fatty acids to high value chiral hydroxy‐acids and lactones poses a number of synthetic challenges: the activation of unreactive C?H bonds and the need for regio‐ and stereoselectivity. Here the first example of a wild‐type cytochrome P450 monooxygenase (CYP116B46 from Tepidiphilus thermophilus) capable of enantio‐ and regioselective C5 hydroxylation of decanoic acid 1 to (S)‐5‐hydroxydecanoic acid 2 is reported. Subsequent lactonization yields (S)‐δ‐decalactone 3 , a high value fragrance compound, with greater than 90 % ee. Docking studies provide a rationale for the high regio‐ and enantioselectivity of the reaction. 相似文献
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