- Approaches to prepare perfluoroalkyl and pentafluorophenyl copper couples for cross-coupling reactions with organohalogen compounds
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The reactions of iodoperfluoroalkanes CnF2n+1I (n = 2, 3, 4) and n-BuLi at low temperatures give NMR spectroscopic evidence for LiCnF2n+1 which were converted into LiCu(CnF2n+1)2 derivatives upon treatment with 0.5 mol copper(i) bromide, CuBr. An alternative route to obtain perfluoroorgano copper couples, Cu(Rf)2Ag (Rf = n-C3F7, n-C4F9, C6F5) was achieved from the reactions of the corresponding perfluoroorgano silver(i) reagents, AgRf, and elemental copper through redox transmetallations. The composition of the resulting reactive intermediates was investigated by means of 19F NMR spectroscopy and ESI mass spectrometry. Perfluoro-n-propyl and perfluoro-n-butyl copper-silver reagents prepared by the oxidative transmetallation route exhibited good properties in C-C bond formation reactions with acid chlorides even under moderate conditions. Substitution of bromine directly bound to aromatics for perfluoroalkyl groups was achieved at elevated temperatures, while success in halide substitution reactions using lithium copper couples remained poor.
- Kremlev, Mikhail M.,Mushta, Aleksej I.,Tyrra, Wieland,Yagupolskii, Yurii L.,Naumann, Dieter,Sch?fer, Mathias
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p. 19693 - 19699
(2015/11/27)
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- Phosphate management with small molecules
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This invention relates to methods and small molecules having a phosphate group that can be used to inhibit phosphate transport and to treat or prevent diseases that are related to disorders in the maintenance of normal serum phosphate levels.
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Page/Page column 27
(2015/12/17)
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- Efficient synthesis of tetradecafluoro-4-phenylheptan-4-ol by a Cannizzaro-type reaction and application of the alcohol as a bulky Martin ligand variant for a new anti-apicophilic phosphorane
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Alcohols 8 bearing two identical perfluoroalkyl groups were prepared by the reaction of the corresponding perfluoroalkyl phenyl ketones 7 with 0.5 equivalents of t-BuOK via Cannizzaro-type disproportionation. Utilizing the new bulky bidentate ligand with two n-C3F7 groups generated from 8c, anti-apicophilic phosphorane 5a and its stable isomer 6a were synthesized. The crystal structures of 5a and 6a were slightly affected by the steric repulsion of heptafluoropropyl groups. Kinetic studies on the isomerization of 5a to 6a showed that the new ligand was effective for decreasing the isomerization rate compared with its C2F5 analog 3a to about half.
- Jiang, Xin-Dong,Matsukawa, Shiro,Kakuda, Ken-Ichiro,Fukuzaki, Yuta,Zhao, Wei-Li,Li, Lin-Song,Shen, Huai-Bin,Kojima, Satoshi,Yamamoto, Yohsuke
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experimental part
p. 9823 - 9829
(2011/01/07)
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- Palladium-catalyzed regio- and stereoselective formate reduction of fluorine-containing allylic mesylates. A new entry for the construction of a tertiary carbon attached with a fluoroalkyl group
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The regioselective palladium-catalyzed formate reduction of γ-fluoroalkylated allylic esters is described. Reduction of the allylic esters under the influence of palladium with a monodentate phosphine ligand proceeded preferentially at the γ position, the corresponding reduction products with a fluoroalkyl group at the tertiary carbon being afforded in high yields. When the chiral allylic ester was employed, complete chirality transfer was observed, leading to the optically active materials in high yields.
- Konno, Tsutomu,Takehana, Tsuyoshi,Mishima, Makoto,Ishihara, Takashi
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p. 3545 - 3550
(2007/10/03)
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- Chiral Synthesis Via Organoboranes. 38 Selective Reductions. 48. Asymmetric Reduction of Trifluoromethyl Ketones by B-Chlorodiisopinocampheylborane in High Enantiomeric Purity
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(-)-B-Chlorodiisopinocampheylborane TM,1>, introduced by us several years ago, has been shown to reduce prochiral aryl and alkyl perfluorinated ketones to the corresponding optically active alcohols in very high ee.For example, 2,2,2-trifluoroacetophenone, trifluoroacetyl-1-naphthalene, and trifluoroacetyl-2-naphthalene are all reduced with 1 within 1-3 d at rt in 90percent ee, 78percent ee and 91percent ee, respectively.The optical purity of 1-phenyl-2,2,2-trifluoroethanol is upgraded to = 99percent ee by crystallizing the initially formed products from pentane. 1,1,2,2,2- pentafluoropropiophenone and 1,1,2,2,3,3,3-heptafluorobutyrophenone are reduced in 3 d with 1 to the corresponding alcohols in 92percent ee and 87 percent ee, respectively.The reagent reduces alkyl trifluoromethyl ketones at a rate faster than that of the aryl derivatives, while still providing the product alcohols in very high ee.Thus, 1,1,1-trifluoroacetone, 1,1,1-trifluorononan-2-one, and 1,1,1-trifluorodecan-2-one are all reduced within 4 - 8 h in 89percent ee, 92percent ee, and 91percent ee, respectively.Even α-sec-alkyl trifluoromethyl ketones are handled by 1 very efficiently.Thus cyclohexyl trifluoromethyl ketone is reduced by 1 at rt in 12 h to the product alcohol in 87percent ee.In all of these cases the trifluoromethyl group acts as the enantiocontrolling larger group as compared to the aryl or alkyl group.This produces alcohol products with stereochemistry opposite to those obtained for the corresponding hydrogen analogs.The steric and electronic influence of the trifluoromethyl group in achieving enantiocontrol in assymmetric reductions is discussed.Keywords: asymmetric reduction; trifluoromethyl ketones; DIP-Chloride; high enantiomeric purity
- Ramachandran, P. Veeraraghavan,Teodorovic, Aleksandar V.,Brown, Herbert C.
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p. 1725 - 1738
(2007/10/02)
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- FLUORO-KETONES IV. SYNTHESIS OF PHENYLPERFLUOROALKYL KETONES - MECHANISM OF REACTION BETWEEN PHENYLLITHIUM AND FLUOROESTERS
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Although fluorine containing ketones (RfC(O)Rf and RfC(O)R, Rf = perfluoroalkyl) have been prepared from the reaction between organolithium reagents and perfluoroalkyl esters, the reaction has not found general applicability.Variable yields of ketones and co-production of secondary and tertiary alcohol by-products have in most instances been experienced.We have examined in more detail the factors e.g., temperature, mode of addition and perfluoroalkyl ester structure which influence ketone product and by-products formation.By controlling experimental conditions excellent yields of C6H5C(O)Rf compounds can be attained.A lithium salt of a hemiketal (II) has been isolated and shown to be the active intermediate in the production of the ketone.The stability of the salt and its potential reaction with the solvent dictates the type of reaction products.Low temperature favors stability of the lithium salt of the hemiketal whereby high yields of ketones are produced on hydrolysis.
- Chen, Loomis S.,Chen, Grace. J.,Tamborski, Christ
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p. 117 - 130
(2007/10/02)
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- POSSIBILITY OF USING ANTIMONY PENTAFLUORIDE INTERCALATED IN GRAPHITE AS CATALYSTS FOR REACTIONS OF THE FRIEDEL-CRAFTS TYPE
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Antimony pentafluoride intercalated in graphite, produced by the reaction of gaseous antimony pentafluoride with powdered graphite in a flow-type system at 140-160 deg C, exhibits the characteristics of liquid antimony pentafluoride in the temperature range of 50-100 deg C and can be used as a catalyst for various processes of the Friedel-Crafts type.The alkylation (by 1-bromooctane, cyclohexene, cyclopentene, and acylation by capryloyl, benzoyl, and perfluorobutyryl chlorides) of benzene were realized.The oxidative characteristics of antimony pentafluoride were used for the generation of the polyatomic doubly charged sulfur cation and electrophilic reagents from polyfluorodiaryl disulfide, lead thiocyanate, and mercuric oxide and their introduction into reaction with benzene.
- Gurin, G. G.,Avramenko, A. A.,Nikonorov, Yu. I.,Yakobson, G. G.
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p. 1340 - 1345
(2007/10/02)
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