- Metal-free tetrahydrofuranylation of alcohols with tertbutyl nitrite
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Metal-free tetrahydrofuranylation of alcohols in the presence of tertbutyl nitrite is described, providing a facile and green route for the protection of hydroxy groups. Mechanistic studies demonstrate that this transformation proceeds in a radical way, and involves alkyl nitrite of corresponding alcohol as the key intermediate.
- Bi, Kang,Cai, Yue-Ming,Lin, Junyue,Liu, Miao-Chang,Zhou, Yun-Bing
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supporting information
(2020/08/06)
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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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- Unexpected Mild Protection of Alcohols as 2-O-THF and 2-O-THP Ethers Catalysed by Cp2TiCl Reveal an Intriguing Role of the Solvent in the Single-Electron Transfer Reaction
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A method for the conversion of primary, secondary and tertiary alcohols into the corresponding THF ethers at room temperature and primary and secondary alcohols into the corresponding THP ethers, has been developed using titanium(III) species generated from a catalytic amount of titanocene dichloride or (4R,5R)-(-)-2,2-dimethyl-α,α,α′,α′-tetra(1-naphthyl)-1,3-dioxolane-4,5-dimethanolatotitanium(IV) dichloride:acetonitrile adduct together with manganese(0) as a reductant and bromoform in THF or THP as the solvent. A radical mechanism is proposed for this transformation revealing an intriguing role of the solvent in the single-electron transfer reactions catalysed by the low valent TiIII system. A set of primary, secondary and benzylic alcohols have been converted into the corresponding THF and THP ethers and tertiary alcohols into the corresponding THF ethers using a catalytic amount of titanium dichloride in good yields and mild reaction conditions.
- Durán-Pe?a, María Jesús,Botubol-Ares, José Manuel,Hanson, James R.,Hernández-Galán, Rosario,Collado, Isidro G.
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p. 6333 - 6340
(2015/10/06)
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- Re2O7-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles
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Re(VII) oxides catalyze the acetalization, monoperoxyacetalization, monothioacetalization and allylation of hemiacetals. The reactions, which take place under mild conditions and at low catalyst loadings, can be conducted using hemiacetals, the corresponding O-silyl ethers, and, in some cases, the acetal dimers. Aldehydes react under similar conditions to furnish good yields of dithioacetals. Reactions of hemiacetals with nitrogen nucleophiles are unsuccessful. 1,2-Dioxolan-3-ols (peroxyhemiacetals) undergo Re(VII)-promoted etherification but not allylation. Hydroperoxyacetals (1-alkoxyhydroperoxides) undergo selective exchange of the alkoxide group in the presence of either Re2O7 or a Bronsted acid.
- Sittiwong, Wantanee,Richardson, Michael W.,Schiaffo, Charles E.,Fisher, Thomas J.,Dussault, Patrick H.
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supporting information
p. 1526 - 1532
(2013/10/22)
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- Vanadium(III) chloride (VCl3): Efficient reagent for the introduction of tetrahydrofuran-based acetal protecting groups for alcohols
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Treatment of different types of alcohols with tetrahydrofuran (THF) in the presence of VCl3 and CCl4 smoothly afforded the corresponding THF-based acetals in excellent yields. The reaction is fast at room temperature, and several functional groups are tolerated, with no racemization being observed. A radical mechanism, based on Cl3C ? as the active species, is proposed for this novel kind of transformation, which complements the classical tetrahydro-2H-pyran-2-yl (THP) protocol.
- Das, Biswanath,Krishnaiah, Maddeboina,Reddy, Vtukuri Saidi,Laxminarayana, Keetha
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p. 2163 - 2166
(2008/03/18)
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- Tetrahydrofuranylation of alcohols using hypervalent iodine reagents
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Alcohols are converted to their corresponding 2-tetrahydrofuranyl ethers using (diacetoxyiodo)benzene in THF. Reactions are carried out under reflux, or, more effectively, under microwave irradiation. Yields up to 81% are reported without the use of chlorinated solvents.
- French, Andrew N.,Cole, Jonathan,Wirth, Thomas
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p. 2291 - 2294
(2007/10/03)
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- Tetrahydrofuranylation of alcohols catalyzed by alkylperoxy- λ3-iodane and carbon tetrachloride
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Reaction of primary and secondary alcohols with tetrahydrofuran and a catalytic amount of 1-tert-butylperoxy-1,2-benziodoxol-3(1H)-one in the presence of carbon tetrachloride at 50°C provides an efficient method for protecting the hydroxy group as 2-tetrahydrofuranyl ethers.
- Ochiai, Masahito,Sueda, Takuya
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p. 3557 - 3559
(2007/10/03)
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- Borane-induced radical reduction of 1-alkenyl- and 1-alkynyl-λ3-iodanes with tetrahydrofuran
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Exposure of 1-alkenyl(phenyl)- and 1-alkynyl(phenyl)-λ3-iodanes to THF at room temperature in the presence of a catalytic amount of trialkylborane results in smooth reduction to give 1-iodo-1-alkenes and 1-iodo-1-alkynes as major products, respectively. The key step in the reductions probably involves a single-electron transfer from α-tetrahydrofuryl radical to the λ3-iodanes, which generates the labile [9-I-2] iodanyl radicals.
- Ochiai, Masahito,Tsuchimoto, Yoshimi,Hayashi, Takanori
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p. 5381 - 5384
(2007/10/03)
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- A convenient synthesis of 2-tetrahydrofuranyl ethers.
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[reaction: see text] A wide spectrum of alcohols and phenols are readily transformed to the corresponding 2-tetrahydrofuranyl ethers in good to excellent yields using CrCl2 and CCl4 in THF under nearly neutral conditions at room temperature.
- Baati,Valleix,Mioskowski,Barma,Falck
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p. 485 - 487
(2007/10/03)
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- An efficient and extremely mild method for protecting alcohols as 2-tetrahydrofuranyl ethers
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Reaction of primary or secondary alcohols with BrCCl3 and tetrahydrofuran, usually in the presence of 2,4,6-collidine, leads to the formation of 2-tetrahydrofuranyl ethers in good to excellent yield (56-92%). The reaction mechanism is believed to involve a free-radical chain reaction. (C) 2000 Elsevier Science Ltd.
- Barks,Gilbert,Parsons,Upeandran
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p. 6249 - 6252
(2007/10/03)
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- Direct Facile Tetrahydrofuranylation Of Alcohols Through Radical Coupling With (Bu4N)2S2O8
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Primary, secondary and tertiary alcohols can be converted in excellent yields into their 2-tetrahydrofuranyl-ethers in the presence of n-tetrabutylammonium peroxydisulfate under nearly neutral condition in tetrahydrofuran.
- Jung, Jae Chul,Choi, Hyun Chul,Kim, Yong Hae
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p. 3581 - 3584
(2007/10/02)
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