- Enantioselective Construction of Tertiary Fluoride Stereocenters by Organocatalytic Fluorocyclization
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1,1-Disubstituted styrenes with internal oxygen and nitrogen nucleophiles undergo oxidative fluorocyclization reactions with in situ generated chiral iodine(III)-catalysts. The resulting fluorinated tetrahydrofurans and pyrrolidines contain a tertiary carbon-fluorine stereocenter. Application of a new 1-naphthyllactic acid-based iodine(III)-catalyst allows the control of tertiary carbon-fluorine stereocenters with up to 96% ee. Density functional theory calculations are performed to investigate the details of the mechanism and the factors governing the stereoselectivity of the reaction.
- Biosca, Maria,Eriksson, Lars,Hedberg, Martin,Himo, Fahmi,Lübcke, Marvin,Szabó, Kálmán J.,Wang, Qiang
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supporting information
p. 20048 - 20057
(2020/11/27)
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- Method for asymmetrically synthesizing (R)-cinacalcet
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The invention discloses a new method for asymmetrically synthesizing (R)-cinacalcet. The method includes: taking racemic 2-bromo-propionic acid (4-methoxybenzyl) ester as a starting raw material, andbeing in asymmetric Negishi cross coupling reaction with 2-nathphyl zinc bromide under catalysis of CoI2 and chiral ligand to generate (R)-2-(1-nathphyl) propionic acid (4-methoxybenzyl) ester; beingin reaction with oxalyl chloride through LiOH reduction to generate (R)-2-(1-nathphyl) propionyl chloride; being reaction with ammonia water to generate (R)-2-(1-nathphyl) propionamide, and allowing Hofmann degradation to obtain (R)-1-nathphalene ethylamine; being in reaction with 3-(trifluoromethyl) phenylpropionic acid to generate (R)-N-(1-nathphalene ethyl)-3-(3-trifluoromethylphenyl) propionamide, and allowing LiAlH4 reduction to obtain (R)-cinacalcet. Cobalt catalyzed asymmetric Negishi cross coupling reaction is utilized for the first time to build the chiral center of (R)-cinacalcet, the method is mild in reaction condition and environment-friendly, and optical purity of (R)-cinacalcet is high (99%ee).
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Paragraph 0026-0028
(2019/03/28)
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- Bismuth-catalyzed synthesis of polycyclic aromatic hydrocarbons (PAHs) with a phenanthrene backbone via cyclization and aromatization of 2-(2-arylphenyl)vinyl ethers
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The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.
- Murai, Masahito,Hosokawa, Naoki,Roy, David,Takai, Kazuhiko
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supporting information
p. 4134 - 4137
(2014/09/30)
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- METHOD OF PRODUCING AN ORGANIC SILICON COMPOUND
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A method of producing an organic silicon compound includes a step of reaction of the following: (A) a reactive silane compound represented by General Formula (1) below: R1mSiY(4-m) (wherein R1 is a monovalent organic group (except for the group represented by Y) or a hydrogen atom; Y indicates a chlorine atom or a group represented by -OR2; R2 indicates a monovalent hydrocarbon group having 1 to 30 carbon atoms; and m is a number in the range of 0 to 3), (B) a halogenated organic compound represented by General Formula (2) below: R3-X (wherein R3 indicates a monovalent organic group; and X is a halogen atom), and (C) metallic magnesium (Mg) in the presence of (D) an organic solvent containing at least one type of ether type compound.
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Paragraph 0053
(2013/07/19)
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- Heteroatom bridged metallocene compounds for olefin polymerization
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This invention relates to a transition metal compound represented by the formula: wherein M is a group 3, 4, 5 or 6 transition metal atom, or a lanthanide metal atom, or actinide metal atom; E is: 1) a substituted or unsubstituted indenyl ligand that is bonded to Y through the four, five, six or seven position of the indenyl ring, or 2) a substituted or unsubstituted heteroindenyl ligand that is bonded to Y through the four, five or six position of the heteroindenyl ring, provided that the bonding position is not the same as the position of the ring heteroatom, or 3) a substituted or unsubstituted fluorenyl ligand that is bonded to Y through the one, two, three, four, five, six, seven or eight position of the fluorenyl ring, or 4) a substituted or unsubstituted heterofluorenyl ligand that is bonded to Y through the one, two, three, four, five or six position of the heteroindenyl ring, provided that the bonding position is not the same as the position of the ring heteroatom; A is a substituted or unsubstituted cyclopentadienyl ligand, a substituted or unsubstituted heterocyclopentadienyl ligand, a substituted or unsubstituted indenyl ligand, a substituted or unsubstituted heteroindenyl ligand, a substituted or unsubstituted fluorenyl ligand, a substituted or unsubstituted heterofluorenyl ligand, or other mono-anionic ligand; Y is a Group 15 or 16 bridging heteroatom substituent that is bonded via the heteroatom to E and A; and X are, independently, univalent anionic ligands, or both X are joined and bound to the metal atom to form a metallocycle ring, or both X join to form a chelating ligand, a diene ligand, or an alkylidene ligand. This invention further relates to catalyst systems comprising the above transiotioon metal compounds, activators and optional supports and their use to polymerize or oligomerize olefins.
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- Arylzinc species by microwave assisted Grignard formation-transmetallation sequence: Application in the Negishi coupling
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Arylmagnesium species can be efficiently generated from magnesium turnings and aryl chlorides or aryl bromides under dielectric heating conditions. Subsequent microwave assisted transmetallation using ZnCl2-TMEDA afforded the corresponding arylzinc reagents. A sequential microwave assisted arylmagnesium formation-transmetallation-Negishi coupling protocol suitable for automated multiple parallel synthesis has been developed.
- Mutule, Ilga,Suna, Edgars
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p. 11168 - 11176
(2007/10/03)
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- 1-Naphthyltropylium Ions Having Condensed Aromatic Rings at the 8-Position: Dependence of the Intramolecular Charge-Transfer Interaction upon Gemetry of the Donor
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A series of 1-aryl-8-tropylionaphthalene cations (aryl = 1-naphthyl (8a), 2-naphthyl (8b), 1-pyrenyl (8c), and 2-pyrenyl (8d) have been synthesized, in which the condensed aromatic system and a tropylium ring are placed at a face-to-face arrangement.The 1H NMR spectra of these cations exhibit remarkable upfield shift for the tropylium ring protons in accord with such molecular geometry; this geometry is further supported by theoretical calculations both by MMP2 and by AM1.The cations 8a-d show the intramolecular charge-transfer (CT) band at 510 (sh) (8a), 525 (sh) (8b), 585 (8c), and 600 (sh) nm (8d) in dichloromethane, indiacting a correlation of the CT transition energy with the donor's ionzation potential regardless of the relative geometry with the acceptor.In contrast, the indicies of cation's thermodynamic stability, pKR+ (6.27 for 8a, 5.45 for 8b, 6.28 for 8c, and 5.75 for 8d), and reduction potential (-0.649 V vs Ag/Ag+ for 8a, -0.601 for 8b, -0.665 for 8c, and -0.625 V for 8d) are highly dependent on the mutual geometry of donor and acceptor, reflecting the effectiveness in overlap of donor's HOMO and acceptor's LUMO.
- Tsuji, Ryotaro,Komatsu, Koichi,Inoue, Yoichiro,Takeuchi, Ken'ichi
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p. 636 - 641
(2007/10/02)
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- 4-Naphthyl derivatives of 7-aminoalkylenoxy-2H-chromene
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Compounds of the formula (I): STR1 and pharmaceutically acceptable salts thereof wherein X is an alkylene group of 2 - 4 carbon atoms; Y is CH2 or 0; R1 is a hydrogen atom or a C1-6 alkyl group; R2 is a hydrogen
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