- An Additive-Free, Base-Catalyzed Protodesilylation of Organosilanes
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We report an additive-free, base-catalyzed C-, N-, O-, and S-Si bond cleavage of various organosilanes in mild conditions. The novel catalyst system exhibits high efficiency and good functional group compatibility, providing the corresponding products in good to excellent yields with low catalyst loadings. Overall, this transition-metal-free process may offer a convenient and general alternative to current employing excess bases, strong acids, or metal-catalyzed systems for the protodesilylation of organosilanes.
- Yao, Wubing,Li, Rongrong,Jiang, Huajiang,Han, Deman
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p. 2250 - 2255
(2018/02/23)
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- Tandem catalytic C(sp3)-H amination/sila-sonogashira-hagihara coupling reactions with iodine reagents
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A new tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations. I(003) is a double agent: A tandem C-N and C-C bond-forming reaction has been achieved through RhII/Pd0 catalysis. The sequence first involves an iodine(III) oxidant, then the in situ generated iodine(I) by-product is used as a coupling partner. The overall process affords complex building blocks with high yields, and demonstrates the synthetic value of iodoarenes produced in trivalent iodine reagent mediated oxidations.
- Buendia, Julien,Darses, Benjamin,Dauban, Philippe
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p. 5697 - 5701
(2015/06/16)
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- One-pot synthesis of 1,3-enynes with a CF3 group on the terminal sp2 carbon by an oxidative Sonogashira cross-coupling reaction
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Oxidative Sonogashira cross-coupling reactions of (E)-trimethyl(3,3,3-trifluoroprop-1-enyl)silane with arylacetylene were achieved using silver fluoride and a palladium catalyst, to afford high yields of various 1,3-enynes with a CF3 group on the terminal sp2 carbon. Silver fluoride promoted C-Si bond dissociation and oxidation of palladium, enabling catalytic use of palladium.
- Ikeda, Akari,Omote, Masaaki,Kusumoto, Kana,Tarui, Atsushi,Sato, Kazuyuki,Ando, Akira
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p. 8886 - 8892
(2015/08/24)
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- Reactivity switch enabled by counterion: Highly chemoselective dimerization and hydration of terminal alkynes
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A counterion-controlled reactivity tuning in Pd-catalyzed highly chemoselective and regioselective dimerization and hydration of terminal alkynes is reported. The use of acetate as counterion favors the formation of an alkenyl alkynyl palladium intermediate which forms hitherto less reported 1,3-diaryl-substituted conjugated enynes after reductive elimination. Using chloride, which is a better leaving group, leads to anion exchange on the alkenylpalladium intermediate with hydroxide which after reductive elimination and tautomerization delivered the hydration products.
- Xu, Caixia,Du, Weiyuan,Zeng, Yi,Dai, Bin,Guo, Hao
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p. 948 - 951
(2014/03/21)
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- Substituted 5-alkynyl pyrimidines having neurotrophic activity
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The present invention relates to a series of novel substituted 5-alkynyl pyrimidines, pharmaceutical compositions which contain them, methods for their preparation, and their use in therapy, particularly in the treatment of neurodegenerative or other neurological disorders of the central and peripheral nervous systems, including age related cognitive disorders such as senility and Alzheimer's disease, nerve injuries, peripheral neuropathies, and seizure disorders such as epilepsy.
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- Synthesis and Physical Properties of Asymmetric Diphenyldiacetylenic Liquid Crystals
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Fifty-six asymmetric diphenyl-diacetylene liquid crystal homologs including dialkyl, alkyl-alkoxy, cyano-alkyl, chloro-alkyl, fluoro-alkyl, difluoro-alkyl, lateral chloro-substituted fluoro-alkyl (or alkoxy), lateral fluoro-substituted asymmetric dialkyl, and vinyl-alkyl are synthesized and their physical properties evaluated.Among these asymmetric diphenyl-diacetylene liquid crystals, many dialkyl homologs exhibit low melting point, wide nematic range, and low heat of fusion.They are ideal host candidates for formulating eutectic mixtures.The polar groups make important contributions to the phase transition temperature, dielectric anisotropy, refractive indices and viscosity.Detailed effects depend on the position of the substitution.These new liquid-crystals compounds and mixtures are particularly useful for electro-optic modulation of infrared radiation. - Keywords: Diphenyl-diacetylenes, eutectic mixtures, electro-optic modulation, physical properties
- Meng, H.-H. B.,Dalton, L. R.,Wu, S.-T.
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p. 303 - 314
(2007/10/02)
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- Substituted benzofurans and benzothiophenes
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The compounds of this invention are substituted benzofurans and benzothiophenes having pharmacological activity. In particular, these compounds have coronary vasodilator activity and are useful in the treatment angina pectoris.
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