- Chiral-Substituted Poly-N-vinylpyrrolidinones and Bimetallic Nanoclusters in Catalytic Asymmetric Oxidation Reactions
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A new class of poly-N-vinylpyrrolidinones containing an asymmetric center at C5 of the pyrrolidinone ring were synthesized from l-amino acids. The polymers, particularly 17, were used to stabilize nanoclusters such as Pd/Au for the catalytic asymmetric oxidations of 1,3- and 1,2-cycloalkanediols and alkenes, and Cu/Au was used for C-H oxidation of cycloalkanes. It was found that the bulkier the C5 substituent in the pyrrolidinone ring, the greater the optical yields produced. Both oxidative kinetic resolution of (±)-1,3- and 1,2-trans-cycloalkanediols and desymmetrization of meso cis-diols took place with 0.15 mol % Pd/Au (3:1)-17 under oxygen atmosphere in water to give excellent chemical and optical yields of (S)-hydroxy ketones. Various alkenes were oxidized with 0.5 mol % Pd/Au (3:1)-17 under 30 psi of oxygen in water to give the dihydroxylated products in >93% ee. Oxidation of (R)-limonene at 25 °C occurred at the C-1,2-cyclic alkene function yielding (1S,2R,4R)-dihydroxylimonene 49 in 92% yield. Importantly, cycloalkanes were oxidized with 1 mol % Cu/Au (3:1)-17 and 30% H2O2 in acetonitrile to afford chiral ketones in very good to excellent chemical and optical yields. Alkene function was not oxidized under the reaction conditions. Mechanisms were proposed for the oxidation reactions, and observed stereo- and regio-chemistry were summarized.
- Hao, Bo,Gunaratna, Medha J.,Zhang, Man,Weerasekara, Sahani,Seiwald, Sarah N.,Nguyen, Vu T.,Meier, Alex,Hua, Duy H.
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supporting information
p. 16839 - 16848
(2017/01/10)
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- Microwave-assisted synthesis of α-hydroxy ketone and α-diketone and pyrazine derivatives from α-halo and α,α′-dibromo ketone
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A novel reaction of α-halo ketone (α-bromo and α-chloro ketone) with irradiation under microwave gave the corresponding α-hydroxyketone and pyrazine derivative in good yields. In the case of α,α′-dibromo ketone, α-diketone was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxyketone, α-diketone, α-chloro ketone and pyrazine derivative.
- Utsukihara, Takamitsu,Nakamura, Hiroaki,Watanabe, Masashige,Akira Horiuchi
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p. 9359 - 9364
(2008/01/27)
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- Photo-irradiation of α-halo carbonyl compounds: A novel synthesis of α-hydroxy- and α,α′-dihydroxyketones
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The reaction of α-halo ketones (α-iodocycloalkanones, α-bromocycloalkanones, α-iodo-β-alkoxy esters, and α-iodoacyclicketones) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketones in good yields. For α-bromoketones, it was found that α-hydroxylation does not occur. However, α-bromoketones were converted into α-hydroxyketones in the presence of KI. In the case of α,α′-diiodo ketones, α,α′-dihydroxyketones, which up to now have scarcely been reported, were obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′- dihydroxyketones.
- Chai, Wen,Takeda, Akihiro,Hara, Makoto,Ji, Shun-Jun,Horiuchi, C. Akira
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p. 2453 - 2463
(2007/10/03)
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- A novel synthesis of α-hydroxy- and α,α′- dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation
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A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′- diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′- dihydroxyketone.
- Horiuchi, C. Akira,Takeda, Akinori,Chai, Wen,Ohwada, Kishoh,Ji, Shun-Jun,Takahashi, T. Tomoyoshi
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p. 9307 - 9311
(2007/10/03)
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- Oxidation reactions catalysed by titanium- and chromium-containing silicalites
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While the titanium silicalite-1 (TS-1)-tert-butyl hydroperoxide (TBHP) combination exhibits remarkable activity and selectivity in the oxidative cleavage of the C-C double bond of silyl enol ethers to produce dicarboxylic acids, the chemoselective oxidation of thioethers to sulfoxides without generation of sulfones is achieved using chromium silicalite-2 (CrS-2)-H2O2.
- Raju, Satya V. N.,Upadhya,Ponrathnam,Daniel,Sudalai
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p. 1969 - 1970
(2007/10/03)
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- BAEYER-VILLIGER OXIDATION WITH Me3SiOOSiMe3 UNDER ASSISTANCE OF SnCl4 OR BF3-OEt2.
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Treatment of ketones with bis(trimethylsilyl) peroxide and Lewis acid such as SnCl//4 or BF//3-OEt//2 in dichloromethane at room temperature affords esters in fair to excellent yields. Jasmine lactone is synthesized from 2- left bracket (Z)-pentenyl right bracket cyclopentanine by means of Me//3SiOOSiMe//3-BF//3-OEt//2 system without any protection of the carbon-carbon double bond. The oxidation of enol acetates of ketones to alpha -hydroxy (or alpha -acetoxy) ketones with Me//3SiOOSiMe//3-FeCl//3 system is also disclosed.
- Matsubara,Takai,Nozaki
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p. 2029 - 2032
(2007/10/02)
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