- The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
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The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
- Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
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supporting information
p. 13695 - 13700
(2020/08/24)
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- Method for synthesizing trans-4-alkylcyclohexyl benzene structure liquid crystal intermediates and monomers
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The invention discloses a method for synthesizing trans-4-alkylcyclohexyl benzene structure liquid crystal intermediates and monomers and belongs to the technical field of trans-cyclohexyl benzene liquid crystal. The method comprises the following steps:
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Paragraph 0042-0044
(2018/03/01)
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- LIQUID CRYSTALLINE COMPOUND HAVING DIFLUOROMETHYLENEOXY GROUP, LIQUID CRYSTAL COMPOSITION, AND LIQUID CRYSTAL DISPLAY ELEMENT
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PROBLEM TO BE SOLVED: To provide a liquid crystalline compound having at least one sufficient property in physical properties such as high stability to heat or light, a high clear point (or high maximum temperature), a low minimum temperature of a liquid
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Paragraph 0158-0159
(2018/04/03)
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- Fluorinated compounds containing naphthalene structure
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PROBLEM TO BE SOLVED: To provide a compound concurrently having a large dielectric anisotropy (Δε), a high clear point (T) and a low viscosity (η), and to provide a liquid crystal composition and a liquid crystal display element including the above compou
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Paragraph 0140
(2016/11/17)
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- Compound having 2-fluorophenyloxymethane structure
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There is provided a compound having a good miscibility with another liquid crystal compound and having a combination of a low viscosity (η), high storage stability, and high T?i even after being used to produce a liquid crystal composition. In
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Page/Page column 168; 169; 171
(2015/12/01)
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- ORTHO ESTER DERIVATIVE, LIQUID CRYSTAL COMPOSITION, AND LIQUID CRYSTAL DISPLAY ELEMENT
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The invention is to provide a liquid crystal compound having a large dielectric anisotropy, a high voltage holding ratio and stability to heat, light and so forth, maintaining a nematic phase in a wide temperature range, having a suitable optical anisotropy and an excellent compatibility with other liquid crystal compounds, particularly, to provide a liquid crystal compound having a large dielectric anisotropy. The invention provides compound (1): In the formula, for example, R1 is alkyl and having 1 to 20 carbons; ring A1, ring A2, ring A3, ring A4, ring A5 and ring A6 are independently 1,4-cyclohexylene or 1,4-phenylene; Z1, Z2, Z3, Z4, Z5, Z6 and Z7 are independently a single bond, - (CH2) 2-, -COO-, -OCO-, CF2O-, -OCF2- or -CH=CH-; X1 is fluorine, -CF3 or -OCF3; and Y1 and Y2 are independently hydrogen or fluorine.
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Paragraph 0395
(2014/02/15)
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- COMPOUND HAVING 2-FLUOROPHENYLOXYMETHANE STRUCTURE
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The present invention relates to a compound having a 2-fluorophenyloxymethane structure and useful for organic electronic materials and medical and agricultural chemicals, particularly materials for liquid crystal display elements. A problem to be solved
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Paragraph 0145; 0149
(2014/09/30)
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- Highly birefringent nematic liquid crystals for reflective STN applications
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An important parameter of any LCD containing portable electronic device is a low power requirement. The reflective STN display mode offers a moderate to high information content display with low power consumption. One method to realise colour in this mode is to use a large retardation (dΔn) value in the cell. For a cell gap of 6 μm, and a retardation of ~1.5, a birefringence (Δn) of greater than +0.2 is necessary. To achieve such a value in an STN LC mixture, materials with broad nematic range, good solubility and a Δn value of +0.25 are required. A study of the trans-cyclohexyldifluorophenyltolane core structure was made and a large number of dialkyl, alkenyl-alkyl and alkoxy materials were synthesised and characterised. These materials possess low to moderate melting points, broad purely nematic mesophases, a high An and very good solubility in nematic LC hosts. They are suitable materials for inclusion in mixtures for colour reflective STN displays.
- Goulding, Mark,Reiffenrath, Volker,Hirschmann, Harald
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p. 899 - 910
(2007/10/03)
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