- Palladium-catalyzed reaction of γ-silylated allyl acetates proceeding through 1,2-shift of a substituent on silicon
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The palladium-catalyzed reaction of γ-silylated allyl acetates with water in the presence of CsF induces a previously unprecedented 1,2-shift of a substituent on silicon to produce allylsilanes in situ. The catalytic activity of the palladium increased when using an electron-poor phosphine ligand possessing fluorinated substituents. Further investigation of the reaction revealed that the approximate order of the migratory aptitude of groups from silicon was PhC≡C, allyl > Bn > Ph, vinyl > alkyl (Me, Et). A density functional theory study was employed to explore the reaction mechanism. Finally, the Hosomi–Sakurai-type allylation of aldehydes with in situ-generated α,γ-disubstituted allylsilanes was also investigated.
- Horino, Yoshikazu,Ishibashi, Mayo,Nakasai, Kosuke,Korenaga, Toshinobu
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- Direct Substitution of Secondary and Tertiary Alcohols to Generate Sulfones under Catalyst- and Additive-Free Conditions
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An environmentally benign protocol that affords propargylic sulfones containing highly congested carbon centers from easily accessible alcohols and sulfinic acids with water as the only byproduct is reported. The reaction proceeded via an in situ dehydrative cross-coupling process by taking advantage of the synergetic actions of multiple hydrogen bonds rather than relying on an external catalyst and/or additives to achieve high product distribution.
- Liu, Yanan,Xie, Peizhong,Sun, Zuolian,Wo, Xiangyang,Gao, Cuiqing,Fu, Weishan,Loh, Teck-Peng
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supporting information
p. 5353 - 5356
(2018/09/13)
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- Developing asymmetric iron and ruthenium-based cyclone complexes; Complex factors influence the asymmetric induction in the transfer hydrogenation of ketones
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The preparation of a range of asymmetric iron and ruthenium-cyclone complexes, and their application to the asymmetric reduction of a ketone, are described. The enantioselectivity of ketone reduction is influenced by a single chiral centre in the catalyst, as well as by the planar chirality in the catalyst. This represents the first example of asymmetric ketone reduction using an iron cyclone catalyst.
- Hopewell, Jonathan P.,Martins, Jose E. D.,Johnson, Tarn C.,Godfrey, Jamie,Wills, Martin
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supporting information; experimental part
p. 134 - 145
(2012/01/12)
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- Heteropolyacid-catalyzed direct deoxygenation of propargyl and allyl alcohols
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The combination of H3[PW12O40] ?nH2O (1 mol %) and Et3SiH led to the direct catalytic deoxygenation of propargyl alcohols, in which proper solvent selection Cl(CH2)2Cl vs CF3CH2OH was the key to obtaining better product yields. Under similar conditions, the deoxygenation of allyl alcohols proceeded to give thermodynamically stable alkenes with migration of the double bonds in good yields.
- Egi, Masahiro,Kawai, Takuya,Umemura, Megumi,Akai, Shuji
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experimental part
p. 7092 - 7097
(2012/10/07)
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- Novel sequential 1,4-Brook rearrangement-Wittig reaction: New one-pot approach for silyl dienol ethers
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A novel one-pot synthetic method of silyl dienol ethers via 1,4-Brook rearrangement-Wittig reaction sequence has been developed. This tandem reaction proceeded via the intramolecular silyl migration step, which enabled stereoselective formation of phosphorane intermediates. The reaction is operationally simple and high yielding, thus providing a new useful formula for silyl dienol ether synthesis.
- Matsuya, Yuji,Koiwai, Azusa,Minato, Daishiro,Sugimoto, Kenji,Toyooka, Naoki
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supporting information
p. 5955 - 5957,3
(2020/07/31)
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- 1,4-Dialkynylbutatrienes: Synthesis, stability, and perspectives in the chemistry of carbo-benzenes
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The π-electron-rich C8-conjugated sequence of 1,4-dialkynylbutatrienes is identified as a fragile and fascinating motif occurring in carbo-benzene derivatives, and in Diederich's 1,4-bis(arylethynyl)- or 1,4-bis(triisopropylsilylethynyl)butatriene "capped" representatives, in particular, in tetraalkynylbutatriene. The family of symmetrical 1,4-dialkynylbutatrienes (E-C≡C)RC=C=C=CR(C≡C-E) is extended to functional caps (E=H, CH3, C≡CPh, CPh=CHBr, or CPh=CBr2) with non-alkynyl substituents at the sp2 vertices (R=Ph or CF3). The targets were selected for their potential in appealing retrosynthetic routes to carbo-benzenes, in which the aromatic C18 macrocycle would be directly generated by sequential metathesis or reductive coupling processes. The functional 1,4-dialkynylbutrienes were synthesized by either classical methods used for the preparation of generic butatrienes (R′Li/CuX-mediated reductive coupling of gem-dihaloenynes or SnCl2/HCl-mediated reduction of 3,6-dioxy-octa-1,4,7-triyne precursors). Their spectroscopic and electrochemical properties are compared and analyzed on the basis of the relative extent of total conjugation.
- Maraval, Valerie,Leroyer, Leo,Harano, Aya,Barthes, Cecile,Saquet, Alix,Duhayon, Carine,Shinmyozu, Teruo,Chauvin, Remi
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supporting information; experimental part
p. 5086 - 5100
(2011/06/09)
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- Facile one-pot syntheses of bromoacetylenes from bulky trialkylsilyl acetylenes
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Because haloalkynes are versatile intermediates in synthetic chemistry, the development of new efficient methods for the conversion of 1-trialkylsilylacetylenes to haloacetylenes in situ remains desirable, especially when the corresponding terminal acetyl
- Lee, Taeho,Kang, Hee Ryong,Kim, Shinae,Kim, Sanghee
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p. 4081 - 4085
(2007/10/03)
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- A direct and stereocontrolled route to conjugated enediynes
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A unified synthetic route to 3-hex-en-1,5-diynes, a key building block found in many of the enediyne antitumor agents and designed materials, was developed. The method, which relies on a carbenoid coupling-elimination strategy is tolerant of a wide range of functionalities, and was applied to the synthesis of a variety of linear and cyclic enediynes. Reaction parameters can be adjusted to control stereoselectivity of the process, producing linear enediynes from 1:12 to >100:1 E:Z ratio, and in the case of cyclic enediynes, giving the exclusively Z C-9, C-10, or C-11 products. Key features of the process are the ready availability of precursors and the mildness and efficiency of the reaction. Application of the process in the design of materials precursors and preparation of enediyne antitumor agents are presented.
- Jones, Graham B.,Wright, Justin M.,Plourde, Gary W.,Hynd, George,Huber, Robert S.,Mathews, Jude E.
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p. 1937 - 1944
(2007/10/03)
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