- Rh-Catalyzed Coupling of Aldehydes with Allylboronates Enables Facile Access to Ketones
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We present herein a novel strategy for the preparation of ketones from aldehydes and allylic boronic esters. This reaction involves the allylation of aldehydes with allylic boronic esters and the Rh-catalyzed chain-walking of homoallylic alcohols. The key to this successful development is the protodeboronation of alkenyl borylether intermediate via a tetravalent borate anion species in the presence of KHF2 and MeOH. This approach features mild reaction conditions, broad substrate scope, and excellent functional group tolerance. Mechanistic studies also supported that the tandem allylation and chain-walking process were involved.
- Zhang, Kezhuo,Huang, Jiaxin,Zhao, Wanxiang
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supporting information
(2022/02/21)
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- 4-Methyltetrahydropyran (4-MeTHP): Application as an Organic Reaction Solvent
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4-Methyltetrahydropyran (4-MeTHP) is a hydrophobic cyclic ether with potential for industrial applications. We herein report, for the first time, a comprehensive study on the performance of 4-MeTHP as an organic reaction solvent. Its broad application to organic reactions includes radical, Grignard, Wittig, organometallic, halogen-metal exchange, reduction, oxidation, epoxidation, amidation, esterification, metathesis, and other miscellaneous organic reactions. This breadth suggests 4-MeTHP can serve as a substitute for conventional ethers and harmful halogenated solvents. However, 4-MeTHP was found incompatible with strong Lewis acids, and the C?O bond was readily cleaved by treatment with BBr3. Moreover, the radical-based degradation pathways of 4-MeTHP, THP and 2-MeTHF were elucidated on the basis of GC-MS analyses. The data reported herein is anticipated to be useful for a broad range of synthetic chemists, especially industrial process chemists, when selecting the reaction solvent with green chemistry perspectives.
- Kobayashi, Shoji,Tamura, Tomoki,Yoshimoto, Saki,Kawakami, Takashi,Masuyama, Araki
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p. 3921 - 3937
(2019/11/11)
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- Preparation of α,n-dilithiotoluene equivalents. Synthesis of tamoxifen
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The successive reaction of chlorobenzyl alcohols with n-butyllithium and lithium powder in the presence of a substoichiometric amount of 4,4′-di-tert-butylbiphenyl (DTBB) at -78°C yields the expected (lithiooxymethyl)phenyllithium derivative, which is trapped by reaction with different ketones. The subsequent arene-catalysed lithiation at 25°C permits the one-pot chemoselective lithiation of the primary benzyl alcoholate in the presence of a tertiary one. These new functionalised benzyllithium derivatives react with different electrophilic compounds, such as aldehydes, ketones and chlorotrimethylsilane, to give after hydrolysis the expected functionalised benzyl alcohols. Some of these alcohols are successfully transformed into mono- or di-olefins by acidic treatment. This whole strategy is applied to the preparation of anti-cancer drug tamoxifen.
- Yus, Miguel,Ramón, Diego J.,Gómez, Inmaculada
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p. 3219 - 3225
(2007/10/03)
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- Regioselective Metallation of Propylbenzene with Superbase: A Convenient Route to Stilbene Derivatives
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The benzylic metallation of propylbenzene has been elaborated with LIC-KOR superbase; the method has been applied in a new synthesis of stilbene derivatives.
- Thurner, Angelika,Agai, Bela,Faigl, Ferenc
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p. 158 - 159
(2007/10/03)
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- Synthesis of Tamoxifen and 4-Hydroxytamoxifen using Super-base-metalated Propylbenzene
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Propylbenzene is metalated regioselectively at the α-carbon using the n-BuLi-t-BuOK-TMEDA super-base combination; the resulting carbanion condenses with functionalised benzophenones to provide direct syntheses of tamoxifen and 4-hydroxytamoxifen.
- Olier-Reuchet, Chantal,Aitken, David J.,Bucourt, Robert,Husson, Henri-Philippe
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p. 8221 - 8224
(2007/10/02)
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- Stereoselective Olefin Formation from the Dehydration of 1-(p-Alkoxyphenyl)-1,2-diphenylbutan-1-ols: Application to the Synthesis of Tamoxifen
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Acid-catalysed dehydration of either diastereoisomer of a 1-(p-alkoxyphenyl)-1,2-diphenylbutan-1-ol gives mainly the Z isomer of the but-1-ene via a common carbenium ion intermediate that can be regenerated by protonation of the (Z)- or (E)-butene with fluorosulphonic acid.Highly stereoselective syn eliminations were achieved by treatment of the butan-1-ols with base and carbon disulphide but dehydrations using N,N,N-triethylammonio-N'-methoxycarbonylsulphamidate proceeded mainly via a carbenium ion.Aspects of the stereoselectivity of the reactions are discussed.The methods can be applied to give simple stereoselective syntheses of the anti-cancer drug tamoxifen.
- McCague, Raymond
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p. 1011 - 1016
(2007/10/02)
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