- Catalytic Syn-Selective Nitroaldol Approach to Amphenicol Antibiotics: Evolution of a Unified Asymmetric Synthesis of (-)-Chloramphenicol, (-)-Azidamphenicol, (+)-Thiamphenicol, and (+)-Florfenicol
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A unified strategy for an efficient and high diastereo- and enantioselective synthesis of (-)-chloramphenicol, (-)-azidamphenicol, (+)-thiamphenicol, and (+)-florfenicol based on a key catalytic syn-selective Henry reaction is reported. The stereochemistry of the ligand-enabled copper(II)-catalyzed aryl aldehyde Henry reaction of nitroethanol was first explored to forge a challenging syn-2-amino-1,3-diol structure unit with vicinal stereocenters with excellent stereocontrol. Multistep continuous flow manipulations were carried out to achieve the efficient asymmetric synthesis of this family of amphenicol antibiotics.
- Chen, Fener,Cheng, Dang,Huang, Huashan,Jiang, Meifen,Liu, Minjie,Qu, Hongmin,Xia, Yingqi,Xiong, Tong,Zhang, Yan
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supporting information
p. 11557 - 11570
(2021/09/02)
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- Custom-Made Pyrene Photocatalyst-Promoted Desulfonylation of Arylethenyl Sulfones Using Green-Light-Emitting Diodes
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The Sonogashira coupling of 1,3,6,8-tetrabromopyrene with 4-[(-)-β-citronellyloxy]phenylethyne was employed to synthesize 1,3,6,8-tetra[4-(citronellyloxy)phenylethynyl]pyrene. The pyrene derivative catalyzed the reductive desulfonylation of ethenyl sulfones via visible-light irradiation (514 nm green light-emitting diodes) in the presence of i -Pr 2NEt. The β-citronellyloxy groups provided the sufficient solubility to the highly π-expanded pyrene catalyst, and their polar oxygen functionalities enabled the easy separation of the catalyst from the products via column chromatography.
- Watanabe, Hikaru,Nakajima, Kazuki,Ekuni, Kento,Edagawa, Ryota,Akagi, Yuta,Okuda, Yasuhiro,Wakamatsu, Kan,Orita, Akihiro
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p. 2984 - 2994
(2021/03/04)
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- NEW COMPOUNDS SUITABLE AS CATALYSTS FOR POLYMERIZATION REACTIONS
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The invention relates to a compound of formula (I) and a process for synthesizing said compound. The invention further relates to the use of said compound as a catalyst, preferably for polymerization, such as, olefin polymerization. The invention also relates to the polymers produced using said catalyst and articles comprising said polymers.
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- Oxidative Dephosphorylation of Benzylic Phosphonates with Dioxygen Generating Symmetrical trans-Stilbenes
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Under a dioxygen atmosphere, benzylphosphonates and related phosphoryl compounds can readily produce the corresponding trans-stilbenes in high yields with high selectivity upon treatment with bases. Various functional groups were tolerable under the reaction conditions.
- Huang, Tianzeng,Chen, Tieqiao,Han, Li-Biao
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p. 2959 - 2965
(2018/03/09)
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- Enantioselective Ethylation of Various Aldehydes Catalyzed by Readily Accessible Chiral Diols
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Four chiral C2-symmetric diols were synthesized in a straightforward three-step reaction and demonstrated excellent enantioselectivities and good overall yields. Their catalytic activities were examined via the addition of diethylzinc to various aldehydes. The enantioselective addition of diethylzinc to 2-methoxybenzaldehyde gave the corresponding chiral secondary alcohol with high yields (up to 95%) and moderate to good enantiomeric excess (up to 88%). All synthesized ligands were evaluated in the addition of diethylzinc to various aldehydes in the presence of an additional metal such as Ti(IV) complexes. Chirality 28:593–598, 2016.
- G?k, Ya?ar,Kili?arslan, Seda,G?k, Halil Zeki,Karayi?it, ?lker ümit
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p. 593 - 598
(2016/08/27)
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- Cyanostilbene deriv., light-emitting element, the light emitting device, lighting device and electronic device
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PROBLEM TO BE SOLVED: To provide such a novel stilbene derivative which permits the luminescence of a shorter wavelength, as is useful for a light-emitting element of a high luminous efficiency, a light-emitting device having an excellent color reproducibility and having an electric power consumption decreased, or the like. SOLUTION: This stilbene derivative is expressed by formula G11 (in the formula, with regard to R10through R12, at least one of them is a tert-butyl group, and the remainder is a hydrogen atom; with regard to R13through R15, at least one of them is a tert-butyl group, and the remainder is a hydrogen atom; and Ar4to Ar5are each a (6-25)C aryl group). COPYRIGHT: (C)2013,JPOandINPIT
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Paragraph 0457; 0462; 0463; 0464
(2019/05/01)
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- Stilbene derivative, light emitting element material, light emitting element, light emitting device and electronic appliance
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An object of the present invention to provide a novel stilbene derivative having a large energy gap. In addition, it is another object of the present invention to provide a novel light emitting element material having a large energy gap which is suitable for a host material in a light emitting layer. Further in addition, it is another object of the present invention to provide a novel light emitting element material having a large energy gap and an electron transporting property. The present invention provides a stilbene derivative represented by a following general formula (3) and a light emitting element material including the stilbene derivative represented thereby: wherein, n is an integer of 0 or more and 2 or less and m is an integer of 1 or more and 2 or less.
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Page/Page column 14
(2008/06/13)
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- Synthesis of a novel silicon-bridged [2.2]metacyclophan-9-ene and its photolytic transannular reaction
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A novel [2.2]metacyclophane in which two benzene rings are linked together with a carbon-carbon double bond and a disilane unit was prepared. Photolysis of the cyclophane in the presence of oxygen afforded the 4,5-dihydro-4,5- disilapyrene derivative via
- Oba, Makoto,Iida, Minoru,Nagoya, Tomoki,Nishiyama, Kozaburo
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p. 1151 - 1153
(2007/10/03)
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- Synthesis of trans-stilbenes utilising decarbonylation of α-chloro chloroformates mediated by samarium diiodide
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A new synthesis of trans-stilbenes has been achieved by decarbonylation of α-chloro chloroformates mediated by samarium diiodide in THF; this one pot reaction is completed within a few minutes at room temperature.
- Li, Zhifang,Zhang, Yongmin
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p. 340 - 341
(2007/10/03)
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- SULFURIC ACID ESTERS OF SUGAR ALCOHOLS
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The present invention is concerned with novel sulfuric acid esters of sugar alcohols and sugar alcohol-like compounds of the formula STR1 Also described are methods for the treatment and/or prophylaxis of arteriosclerotic changes in the vascular wall as well as a process for the manufacture of the compounds of formula I and their salts.
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- Palladium(0) complex-catalyzed debrominative coupling of (tribromomethyl)- and (dibromomethyl)benzenes to diarylacetylenes and 1,2-diarylethenes
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Palladium(0)-triphenylphosphine complex-catalyzed debrominative coupling reaction of (tribromomethyl)benzenes gave diarylacetylenes or a mixture of (E)- and (Z)-α,β-dibromostilbenes depending upon the substrate and the solvent being used. On the other hand, (dibromomethyl)benzenes afforded (E)-stilbenes selectively under the same reaction conditions.
- Mataka,Liu,Tashiro
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p. 133 - 135
(2007/10/02)
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- Evidence for Bromine-Lithium Exchange in a Local High Concentration Gradient
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The product ratios for bromine-lithium exchange of 3,3'-dibromostilbene (6) with one equivalent of n-butyl lithium, s-butyl lithium or t-butyl lithium in THF and in Et2O to give after quenching with methanol 3-bromostilbene (7) and stilbene (8), have been investigated.In the reactive cases the ratio of 8:7 is significantly greater than expected for a statistical reaction.The apparently accelerated exchange of 7-Li relative to 6 is attributed to reaction in a high local concentration of the butyl lithium reagent.
- Beak, Peter,Liu, Chao
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p. 5999 - 6004
(2007/10/02)
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- MAGNETIC COUPLING BETWEEN TWO PHENOXYL RADICALS ATTACHED TO THE PHENYL RINGS OF CIS- AND TRANS-STILBENES
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Magnetic coupling between two sterically protected phenoxyl radicals through the cis- and trans-stilbene chromophores was studied by means of their EPR fine structures.While the zero-field splitting parameters D, which are governed by the magnitude of dip
- Mitsumori, Teruyuki,Koga, Noboru,Iwamura, Hiizu
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- Semiempirical Investigation of Stilbene-Linked Diradicals and Magnetic Study of Their Bis(N-tert-butylnitroxide) Variants
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The electronic states of open-shell stilbene diradicals were studied.Previously used semiempirical MO-CI methods were applied to stilbenes having dimethylene, dioxyl, and dinitroxide centers in o,o'-, o,m'-, o,p'-, m,m'-, m,p'-, and p,p'-substitution patterns, and the various singlet-triplet energy gaps were computed to predict qualitative ground state spin multiplicities.Singlet and triplet spin states were essentially degenerate in the m,m'-isomers of disjoint connectivity, while nondisjoint o,m'- and m,p'-isomers had triplet computed ground states.Nitroxide-based diradicals showed considerably smaller computational exchange coupling energies than did other diradicals models studied.As a tests of these computations, stilbenes with two N-tert-butyl nitroxide groups at the o,m'-, m,m'-, and m,p'-positions were prepared, and their magnetic properties were studied by ESR and magnetic susceptibility measurements.The m,m'- and m,p'-isomers were found experimentally to have singlet and triplet ground states, respectively, in accord with the qualitative computed predictions.
- Yoshioka, Naoki,Lahti, Paul M.,Kaneko, Takashi,Kuzumaki, Yoshihiro,Tsuchida, Eishun,Nishide, Hiroyuki
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p. 4272 - 4280
(2007/10/02)
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