- Diarylrhodates as promising active catalysts for the arylation of vinyl ethers with grignard reagents
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Anionic diarylrhodium complexes, generated by reacting [RhCl(cod)] 2 with 2 equiv of aryl Grignard reagents, were found to be effective active catalysts in cross-coupling reactions of vinyl ethers with aryl Grignard reagents, giving rise to the production of vinyl arenes. In this catalytic system, vinyl-O bonds were preferably cleaved over Ar-O or Ar-Br bonds. A lithium rhodate complex was isolated, and its crystal structure was determined by X-ray crystallography.
- Iwasaki, Takanori,Miyata, Yoshinori,Akimoto, Ryo,Fujii, Yuuki,Kuniyasu, Hitoshi,Kambe, Nobuaki
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supporting information
p. 9260 - 9263
(2014/07/21)
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- Mechanistic insight into halide oxidation by non-heme iron complexes. Haloperoxidase versus halogenase activity
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This work presents the first detailed study on mechanistic aspects of halide oxidation by non-heme iron complexes. We show that while iron(iii)-hydroperoxo complexes oxidise halides via oxygen atom transfer, the corresponding iron(iv)-oxo complex reacts via electron transfer. This journal is The Royal Society of Chemistry 2013.
- Vardhaman, Anil Kumar,Barman, Prasenjit,Kumar, Suresh,Sastri, Chivukula V.,Kumar, Devesh,De Visser, Sam P.
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p. 10926 - 10928
(2013/11/19)
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- Expanded substrate scope and improved reactivity of ether-forming cross-coupling reactions of organotrifluoroborates and acetals
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Mixed acetals and organotrifluoroborates undergo BF3· OEt2-promoted cross-couplings to give dialkyl ethers under simple, mild conditions. A survey of reaction partners identified a hydroxamate leaving group that improves the regioselectivity and product yield in the BF 3·OEt2-promoted coupling reaction of mixed acetals and potassium alkynyl-, alkenyl-, aryl- and heteroaryltrifluoroborates to access substituted dialkyl ethers. This leaving group enables the reaction to proceed rapidly under mild conditions (0 °C, 5-60 min) and permits reactions with electron-deficient potassium aryltrifluoroborates that are less reactive with other acetal substrates. A study of the reaction mechanism and characterization of key intermediates by NMR spectroscopy and X-ray crystallography identified a role for the hydroxamate moiety as a reversible leaving group that serves to stabilize the key oxocarbenium intermediate and the need for a slight excess of organodifluoroborane to serve as a catalyst. A secondary role for the boron nucleophile as an activating ligand was also considered. These studies provide the basis for a general class of reagents that lead to dialkyl ethers by a simple, predictable cross-coupling reaction.
- Vo, Cam-Van T.,Mitchell, T. Andrew,Bode, Jeffrey W.
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supporting information; experimental part
p. 14082 - 14089
(2011/10/12)
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- Chlorination of various substrates in subcritical carbon tetrachloride
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Various aliphatic hydrocarbons and the side chains of aromatic hydrocarbons were chlorinated in subcritical carbon tetrachloride. Chlorination of aromatic compounds including 1,4-disubstituted benzenes was investigated. Ketones and sulfones were stable under the employed conditions. Sulfoxides were converted into sulfides in a low to modest yields. The coupling adducts between olefins and carbon tetrachloride were obtained from the reactions of olefins.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Horaguchi, Takaaki
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experimental part
p. 2881 - 2888
(2010/06/16)
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- Chlorination of aliphatic hydrocarbons, aromatic compounds, and olefins in subcritical carbon tetrachloride
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The reactions of various substrates including aliphatic hydrocarbons, aromatic compounds, and olefins were investigated in subcritical carbon tetrachloride. Ketones and sulfones were stable under the employed conditions. The coupling adducts between olefins and carbon tetrachloride were obtained from the reactions of olefins.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Horaguchi, Takaaki
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scheme or table
p. 6419 - 6422
(2009/04/06)
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- Synthesis and nucleophilic substitution reactions of mono α-fluoro ethers
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Mono α-fluoro ethers have been prepared by cleavage of α-alkoxy sulfoxides with diethylaminosulfur trifluoride (DAST) and by an exchange reaction of the corresponding α-chloro ether with tetrabutylammonium fluoride (TBAF). The reactivity of different α-fluoro ethers in some nucleophilic substitution reactions has been investigated. Copyright Acta Chemica Scandinavica 1999.
- Ringom, Rune,Benneche, Tore
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- Intramolecular ortho and meta photocycloadditions of 3-alkyl-4-phenoxybut-1-enes
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Upon irradiation of 3-alkyl-4-phenoxybut-1-enes 1a-d at 254 nm in cyclohexane, ortho and meta photocycloadditions occur. The ortho photocycloadducts rearrange readily, while the meta photocycloaddition involves the 2′,6′-positions of the arene as directed
- Van Der Eycken, Erik,De Keukeleire, Denis,De Bruyn, Andre
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p. 3573 - 3576
(2007/10/02)
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- Substituted pyrimidin-2-ones and the salts thereof
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Compounds of the general formula: STR1 (wherein X represents a halogen atom or a trifluoromethyl group; R1 and R2 independently represent a hydrogen atom or a lower alkyl group; Z is --O--, --S--, --SO--, --SO2 -- or the group --NR4 -- wherein R4 is as defined for R hereinafter or represents the group COR5 in which R5 represents a hydrogen atom or an optionally substituted aryl, heterocyclic, aralkyl, lower alkyl or lower alkoxy group; R represents a C6-10 carbocyclic aromatic group or a heterocyclic group containing a 5-9 membered unsaturated or aromatic heterocyclic ring which ring contains one or more heteroatoms selected from O, N and S and optionally carries a fused ring which carbocyclic or heterocyclic group may carry one or more C1-4 alkyl or phenyl groups, said groups being optionally substituted; or, where Z represents the group >NR4, the group --ZR may represent a heterocyclic ring optionally carrying a fused ring and/or optionally substituted as defined for R; and R3 represents a hydrogen atom or a lower alkyl, lower alkenyl, lower alkynyl, lower alkanoyl, lower alkenoyl, C7-16 aralkyl or C6-10 arly group or a 5-9 membered unsaturated or aromatic heterocyclic ring); and, where acid or basic groups are present, the salts thereof; are useful in combating abnormal cell proliferation. The compounds of the invention are prepared by inter alia alkylation, ring closure and oxidation.
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- MECHANISMS OF EPOXIDATIONS AND CHLORINATIONS OF HYDROCARBONS BY INORGANIC HYPOCHLORITE IN THE PRESENCE OF A PHASE-TRANSFER CATALYST.
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Inorganic hypochlorite in the presence of a quarternary ammonium salt (phase-transfer catalyst) not only epoxidizes several arenes to arene oxides in high yields but also converts toluene to alpha -chlorotoluene, anisole to ring chlorinated anisoles, and alkenes to a complex mixture of chlorinated and oxidized products, including the epoxide. More detailed studies with this system indicate the following: (1) the high-yield conversion of toluenes to benzyl chlorides proceeds with a deuterium isotope effect of 3. 6 and a rho ** plus value of minus 1. 7: (2) p-chloroanisole is the major product from anisole and is formed in a 22-fold greater quantity than o-chloroanisole; (3) the epoxidation of cis- and trans-alkenes is stereoselective but not completely stereospecific; (4) the chlorination of saturated hydrocarbons occurs with a selectivity that is experimentally identical with that of chlorine monoxide.
- Fonouni,Krishnan,Kuhn,Hamilton
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p. 7672 - 7676
(2007/10/02)
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- Synthesis of α-Haloalkyl Aryl Ethers from O,S-Acetals
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α-Haloalkyl aryl ethers are prepared under mild conditions in high yileds by selective cleavage of O,S-acetals using sulfuryl chloride or bromine.The intermediate O,S-acetal is prepared from the phenol by O-alkylation using a readily accessible α-haloalkyl thioether.
- Benneche, Tore,Undheim, Kjell
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- 5-Fluorouracil derivatives
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5-Fluorouracil derivatives and a process for their preparation are provided. The 5-fluorouracil derivatives according to the invention have the general formula: STR1 R1 and R2 are the same or different and are hydrogen or STR2 with the proviso that both R1 and R2 are not hydrogen at the same time. A1, A2 and A3 are independently selected from hydrogen, and optionally substituted alkoxy and phenyloxy; at least one of A1, A2 and A3 being other than hydrogen. The 5-fluorouracil derivative is prepared by condensing 5-fluorouracil with a halide of the formula: STR3 in the presence of a base. The 5-fluorouracils according to the invention show anti-tumor activity.
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