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981.
Identification of HcgC as a SAM‐Dependent Pyridinol Methyltransferase in [Fe]‐Hydrogenase Cofactor Biosynthesis
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Dr. Takashi Fujishiro Liping Bai Dr. Tao Xu Dr. Xiulan Xie Dr. Michael Schick Jörg Kahnt Prof. Dr. Michael Rother Prof. Dr. Xile Hu Dr. Ulrich Ermler Dr. Seigo Shima 《Angewandte Chemie (International ed. in English)》2016,55(33):9648-9651
Previous retrosynthetic and isotope‐labeling studies have indicated that biosynthesis of the iron guanylylpyridinol (FeGP) cofactor of [Fe]‐hydrogenase requires a methyltransferase. This hypothetical enzyme covalently attaches the methyl group at the 3‐position of the pyridinol ring. We describe the identification of HcgC, a gene product of the hcgA‐G cluster responsible for FeGP cofactor biosynthesis. It acts as an S‐adenosylmethionine (SAM)‐dependent methyltransferase, based on the crystal structures of HcgC and the HcgC/SAM and HcgC/S‐adenosylhomocysteine (SAH) complexes. The pyridinol substrate, 6‐carboxymethyl‐5‐methyl‐4‐hydroxy‐2‐pyridinol, was predicted based on properties of the conserved binding pocket and substrate docking simulations. For verification, the assumed substrate was synthesized and used in a kinetic assay. Mass spectrometry and NMR analysis revealed 6‐carboxymethyl‐3,5‐dimethyl‐4‐hydroxy‐2‐pyridinol as the reaction product, which confirmed the function of HcgC. 相似文献
982.
Metal‐Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent‐Iodine‐Promoted Oxidative C−C Bond Formation
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Mio Shimogaki Prof. Dr. Morifumi Fujita Prof. Dr. Takashi Sugimura 《Angewandte Chemie (International ed. in English)》2016,55(51):15797-15801
The enantioselective oxyarylation of (E)‐6‐aryl‐1‐silyloxylhex‐3‐ene was achieved using a lactate‐based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved. 相似文献
983.
Thermally Induced Intra‐Carboxyl Proton Shuttle in a Molecular Rack‐and‐Pinion Cascade Achieving Macroscopic Crystal Deformation
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Dr. You‐Gui Huang Yoshihito Shiota Sheng‐Qun Su Shu‐Qi Wu Zi‐Shuo Yao Guo‐Ling Li Shinji Kanegawa Soonchul Kang Takashi Kamachi Kazunari Yoshizawa Prof. Katsuhiko Ariga Prof. Osamu Sato 《Angewandte Chemie (International ed. in English)》2016,55(47):14628-14632
Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra‐carboxyl proton shuttle can be generated in a molecular assembly akin to a rack‐and‐pinion cascade via a thermally induced single‐crystal‐to‐single‐crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4′‐azopyridine (azpy) molecule connects to two biphenyl‐3,3′,5,5′‐tetracarboxylic acid (H4BPTC) molecules to form a functional molecular system with switchable mechanical properties. A temperature change reversibly triggers a molecular movement akin to a rack‐and‐pinion cascade, which mainly involves 1) an intra‐carboxyl proton shuttle coupled with tilting of the azo molecules and azo pedal motion and 2) H4BPTC translation. Moreover, both the molecular motions are collective, and being propagated across the entire framework, leading to a macroscopic crystal expansion and contraction. 相似文献
984.
[structure: see text]. We have developed a cationic rhodium(I)/Solphos complex-catalyzed asymmetric one-pot transesterification and [2 + 2 + 2] cycloaddition of 1,6-diyne esters with tertiary propargylic alcohols leading to enantioenriched tricyclic 3,3-disubstituted phthalides. The present method represents a versatile new route to the synthesis of enantioenriched tricyclic 3,3-disubstituted phthalides in view of the easy access to both coupling partners. 相似文献
985.
Direct arylation of aryl(azaaryl)methanes with aryl halides takes place at the benzylic position in the presence of a hydroxide base under palladium catalysis to yield triarylmethanes. 相似文献
986.
987.
988.
Solid-phase synthesis of epigallocatechin gallate derivatives 总被引:1,自引:0,他引:1
Tanaka H Miyoshi H Chuang YC Ando Y Takahashi T 《Angewandte Chemie (International ed. in English)》2007,46(31):5934-5937
989.
990.