- Synthesis of β-acetoxy alcohols by PhI(OAc)2-mediated metal-free diastereoselective β-acetoxylation of alcohols
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β-Acetoxy alcohols can be synthesized in good yields with excellent diastereoselectivity from tertiary alcohols through PhI(OAc)2-mediated metal-free β-acetoxylation. Mechanistic studies showed that the β-acetoxylation process might undergo dehydration and sequential highly regioselective and diastereoseletive dioxygenation. Gram scale and diverse useful scaffolds could be prepared via this β-acetoxylation process.
- Zhao, Chun-Yang,Li, Liang-Gui,Liu, Qing-Rong,Pan, Cheng-Xue,Su, Gui-Fa,Mo, Dong-Liang
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p. 6795 - 6803
(2016/07/23)
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- Manganese(III)-Mediated Free-Radical Cyclization of Active Methylene Compounds, Alkenes and Molecular Oxygen. Syntheses of Sulfur- and Phosphorus-Containing 1,2-Dioxan-3-ols
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The reactions of β-keto sulfoxide, β-keto sulfones, or β-keto phosphinate with 1,1-disubstituted ethenes in the presence of manganese(III) acetate and molecular oxygen yielded 4-phenylsulfinyl-, 4-phenylsulfonyl-, or 4-phosphinoyl-1,2-dioxan-3-ols 3 in moderate-to-good yields. m-Chloroperbenzoic acid oxidation of 4-phenylsulfinyl-1,2-dioxan-3-ols gave the corresponding 4-phenylsulfonyl derivatives.The temperature dependence of the reactions was observed and the stereochemistry of the 1,2-dioxan-3-ols are discused.
- Qian, Chang-Yi,Nishino, Hiroshi,Kurosawa, Kazu
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p. 209 - 216
(2007/10/02)
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- Manganese(II)- and (III)-mediated Free-radical Cyclisation of Alkenes, β-Keto Esters and Molecular Oxygen
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The reactions of substituted ethenes with β-keto esters in the presence of a mixture of manganese(II) and manganese(III) acetates, and molecular oxygen yielded substituted 1,2-dioxan-3-ols 3 in 14-95percent yields.Cobalt(III) acetate, potassium permanganate, lead(IV) acetate, copper(II) acetate, chromium(VI) trioxide, thallium(III) acetate, ammonium cerium(IV) nitrate and iron(III) perchlorate were also used in place of manganese(III) acetate.Effects on the product yields of substituents in the alkenes and β-keto esters have been examined and reaction mechanisms are discussed.
- Yamada, Takashi,Iwahara, Yoko,Nishino, Hiroshi,Kurosawa, Kazu
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p. 609 - 616
(2007/10/02)
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- Formation of 1,2-Dioxanes by the Use of Tris(2,4-pentanedionato)manganese(III) or Manganese(III) Acetate
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The reactions of 1,1-diphenylethene, 1,1-bis(4-chlorophenyl)ethene, 1,1-bis(4-methoxyphenyl)ethene, 1,1-bis(4-methylphenyl)ethene, 1,1-bis(4-fluorophenyl)ethene, styrene, 1-octene, cyclohexene, and cyclooctene with tris(2,4-pentanedionato)manganese(III) () in acetic acid at room temperature give 4-acetyl-3-methyl-1,2-dioxan-3-ol in 8-92percent yields, together with 3-acetyl-4-hydroxy-3-hexene-2,5-dione.The similar reactions of 1,1-diphenylethene with 2,4-pentanedione, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 1-phenyl-1,3-butanedione, acetoacetanilide, and 1,3-cyclohexanedione in the presence of manganese(III) acetate also give the corresponding cyclic peroxide in good to moderate yields.The mechanisms of manganese(III)-induced 1,2-dioxane ring formation and concomitant radical side reaction are discussed.
- Nishino, Hiroshi,Tategami, Shin-ichi,Yamada, Takashi,Korp, James D.,Kurosawa, Kazu
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p. 1800 - 1809
(2007/10/02)
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- Olefin Oxidation Initiated by a Ground-State Electron Acceptor
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The reaction between 1,1-diphenylethylene (DPE) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF4) in air-saturated acetic acid mimics the photochemical electron-transfer oxidation of this olefin.However, the mechanism of the photooxidation is apparently quite different from that observed for the TCNQF4-mediated reaction.In the latter case a peroxide-initiated free-radical oxidation occurs.
- Peacock, Nancy J.,Schuster, Gary B.
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p. 3356 - 3358
(2007/10/02)
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- OXIDATION BY COBALT(III) ACETATE. PART 6. A NOVEL SYNTHESIS OF THE GLYCOL MONOACETATES FROM AROMATIC OLEFINS IN WET ACETIC ACID
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Oxidation of various aryl-conjugated olefins with cobalt(III) acetate in wet acetic acid under nitrogen affords the glycol monoacetates in moderate to good yields.None of the phenyl rearrangement product is formed in the present reactions.These results are best interpreted by assuming the formation of a Co-co-ordinated intermediate.
- Hirano, Masao,Morimoto, Takashi
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p. 1033 - 1036
(2007/10/02)
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