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991.
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994.
Platinum‐Catalyzed Cascade Rearrangement Reaction of 1,5‐Diynyl Esters: Unusual Regioselective 1,5‐Hydride Migration 下载免费PDF全文
A highly regioselective sequential 1,3‐acyloxy migration/pentannulation/1,5‐hydride migration reaction is disclosed which provides an efficient access to (E)‐2‐vinyl‐3‐oxo‐1‐methyleneindenes under neutral and mild reaction conditions. The migrated hydrogen atom was derived from an unactivated alkyl group, and the long‐range 1,5‐H shift was confirmed through related deuterium experiments. 相似文献
995.
996.
Dual Functioning Thieno‐Pyrrole Fused BODIPY Dyes for NIR Optical Imaging and Photodynamic Therapy: Singlet Oxygen Generation without Heavy Halogen Atom Assistance 下载免费PDF全文
Dr. Ryan L. Watley Dr. Samuel G. Awuah Dr. Moses Bio Robert Cantu Habtom B. Gobeze Dr. Vladimir N. Nesterov Dr. Sushanta K. Das Prof. Dr. Francis D'Souza Prof. Dr. Youngjae You 《化学:亚洲杂志》2015,10(6):1335-1343
We discovered a rare phenomenon wherein a thieno‐pyrrole fused BODIPY dye (SBDPiR690) generates singlet oxygen without heavy halogen atom substituents. SBDPiR690 generates both singlet oxygen and fluorescence. To our knowledge, this is the first example of such a finding. To establish a structure–photophysical property relationship, we prepared SBDPiR analogs with electron‐withdrawing groups at the para‐position of the phenyl groups. The electron‐withdrawing groups increased the HOMO–LUMO energy gap and singlet oxygen generation. Among the analogs, SBDPiR688, a CF3 analog, had an excellent dual functionality of brightness (82290 m ?1 cm?1) and phototoxic power (99170 m ?1 cm?1) comparable to those of Pc 4, due to a high extinction coefficient (211 000 m ?1 cm?1) and balanced decay (Φflu=0.39 and ΦΔ=0.47). The dual functionality of the lead compound SBDPiR690 was successfully applied to preclinical optical imaging and for PDT to effectively control a subcutaneous tumor. 相似文献
997.
Victoria L. Challinor Ryne C. Johnston Paul V. Bernhardt Reginald P. Lehmann Elizabeth H. Krenske James J. De Voss 《Chemical science》2015,6(10):5740-5745
A series of novel sesterterpenes (2–6) have been isolated from the roots of Aletris farinosa and structurally characterized by MS, NMR, and X-ray crystallography in conjunction with computational modeling. Their structures provide new insights into the mechanisms of sesterterpene biosynthesis. Specifically, we propose with support from density functional theory computations that the configuration at a single stereocenter determines the fate of a key tetracyclic carbocationic intermediate, derived from an oxidogeranylfarnesol precursor. Whereas one epimer of the carbocation undergoes H+ elimination to give 6, the other undergoes a spectacular cascade of seven 1,2-methyl and hydride migrations leading to the previously unreported carbon skeleton of 5. Theoretical calculations suggest that the cascade is triggered by substrate preorganization in the enzyme active site. 相似文献
998.
Xinchen Kang Wenting Shang Qinggong Zhu Jianling Zhang Tao Jiang Buxing Han Zhonghua Wu Zhihong Li Xueqing Xing 《Chemical science》2015,6(3):1668-1675
We proposed a strategy to synthesize mesoporous inorganic salt particles using the special properties of ionic liquid (IL) mixtures, and hollow mesoporous LaF3, NdF3, and YF3 particles were synthesized and characterized using different techniques. The size of the mesopores in the salt particles was about 4 nm, and the materials were full of crystal defects. The LaF3, NdF3 and YF3 particles were used as the catalysts for the cyanosilylation reaction of benzaldehyde using trimethylsilyl cyanide, and Ru/LaF3 and Ru/NdF3, in which Ru nanocatalysts were supported on the LaF3 and NdF3 particles with mesopores, were used to catalyze hydrogenations of benzene to cyclohexane and levulinic acid (LA) to γ-valerolactone (GVL). It was discovered that the activities of these catalysts were unprecedentedly high for these reactions. Detailed study showed that both the crystal defects and the mesopores in the salt particles played crucial roles for the extremely high catalytic activity. 相似文献
999.
Sarah A. Shepherd Chinnan Karthikeyan Jonathan Latham Anna-Winona Struck Mark L. Thompson Binuraj R. K. Menon Matthew Q. Styles Colin Levy David Leys Jason Micklefield 《Chemical science》2015,6(6):3454-3460
Flavin-dependent halogenases are potentially valuable biocatalysts for the regioselective halogenation of aromatic compounds. These enzymes, utilising benign inorganic halides, offer potential advantages over traditional non-enzymatic halogenation chemistry that often lacks regiocontrol and requires deleterious reagents. Here we extend the biocatalytic repertoire of the tryptophan halogenases, demonstrating how these enzymes can halogenate a range of alternative aryl substrates. Using structure guided mutagenesis we also show that it is possible to alter the regioselectivity as well as increase the activity of the halogenases with non-native substrates including anthranilic acid; an important intermediate in the synthesis and biosynthesis of pharmaceuticals and other valuable products. 相似文献
1000.
Jeffrey F. Van Humbeck Michael L. Aubrey Alaaeddin Alsbaiee Rob Ameloot Geoffrey W. Coates William R. Dichtel Jeffrey R. Long 《Chemical science》2015,6(10):5499-5505
A new family of solid polymer electrolytes based upon anionic tetrakis(phenyl)borate tetrahedral nodes and linear bis-alkyne linkers is reported. Sonogashira polymerizations using tetrakis(4-iodophenyl)borate, tetrakis(4-iodo-2,3,5,6-tetrafluorophenyl)borate and tetrakis(4-bromo-2,3,5,6-tetrafluorophenyl)borate delivered highly cross-linked polymer networks with both 1,4-diethynylbeznene and a tri(ethylene glycol) substituted derivative. Promising initial conductivity metrics have been observed, including high room temperature conductivities (up to 2.7 × 10–4 S cm–1), moderate activation energies (0.25–0.28 eV), and high lithium ion transport numbers (up to t
Li+ = 0.93). Initial investigations into the effects of important materials parameters such as bulk morphology, porosity, fluorination, and other chemical modification, provide starting design parameters for further development of this new class of solid electrolytes. 相似文献