- Catalytic Deprotection of Protected Alcohols in Water Using Low-Loading and Alkylated Polystyrene-Supported Sulfonic Acid
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Catalytic deprotection of various protected alcohols was efficiently conducted using a hydrophobic low-loading and alkylated polystyrene-supported sulfonic acid (LL-ALPS-SO3H) in water as the sole solvent. Transprotection of an alcohol from a silyl ether to the corresponding benzylic ether or ester also proceeded smoothly in water.
- Iimura, Shinya,Manabe, Kei,Kobayashi, Shu
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- Biomimetic ketone reduction by disulfide radical anion
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The conversion of ribonucleosides to 2′-deoxyribonucleosides is catalyzed by ribonucleoside reductase enzymes in nature. One of the key steps in this complex radical mechanism is the reduction of the 3′-ketodeoxynucleotide by a pair of cysteine residues, providing the electrons via a disulfide radical anion (RSSR??) in the active site of the enzyme. In the present study, the bioinspired conversion of ketones to corresponding alcohols was achieved by the intermediacy of disulfide radical anion of cysteine (CysSSCys)?? in water. High concentration of cysteine and pH 10.6 are necessary for high-yielding reactions. The photoinitiated radical chain reaction includes the one-electron reduction of carbonyl moiety by disulfide radical anion, protonation of the resulting ketyl radical anion by water, and H-atom abstraction from CysSH. The (CysSSCys)?? transient species generated by ionizing radiation in aqueous solutions allowed the measurement of kinetic data with ketones by pulse radiolysis. By measuring the rate of the decay of (CysSSCys)?? at λmax = 420 nm at various concentrations of ketones, we found the rate constants of three cyclic ketones to be in the range of 104–105 M?1s?1 at ~22?C.
- Barata-Vallejo, Sebastian,Bobrowski, Krzysztof,Chatgilialoglu, Chryssostomos,Ferreri, Carla,Marciniak, Bronislaw,Skotnicki, Konrad
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- Protodeboronation of (Hetero)Arylboronic Esters: Direct versus Prehydrolytic Pathways and Self-/Auto-Catalysis
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The kinetics and mechanism of the base-catalyzed hydrolysis (ArB(OR)2→ ArB(OH)2) and protodeboronation (ArB(OR)2→ ArH) of a series of boronic esters, encompassing eight different polyols and 10 polyfluoroaryl and heteroaryl moieties, have been investigated by in situ and stopped-flow NMR spectroscopy (19F,1H, and11B), pH-rate dependence, isotope entrainment,2H KIEs, and KS-DFT computations. The study reveals the phenomenological stability of boronic esters under basic aqueous-organic conditions to be highly nuanced. In contrast to common assumption, esterification does not necessarily impart greater stability compared to the corresponding boronic acid. Moreover, hydrolysis of the ester to the boronic acid can be a dominant component of the overall protodeboronation process, augmented by self-, auto-, and oxidative (phenolic) catalysis when the pH is close to the pKaof the boronic acid/ester.
- Hayes, Hannah L. D.,Wei, Ran,Assante, Michele,Geogheghan, Katherine J.,Jin, Na,Tomasi, Simone,Noonan, Gary,Leach, Andrew G.,Lloyd-Jones, Guy C.
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supporting information
p. 14814 - 14826
(2021/09/13)
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- Radical dehydroxylative alkylation of tertiary alcohols by Ti catalysis
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Deoxygenative radical C?C bond-forming reactions of alcohols are a long-standing challenge in synthetic chemistry, and the current methods rely on multistep procedures. Herein, we report a direct dehydroxylative radical alkylation reaction of tertiary alcohols. This new protocol shows the feasibility of generating tertiary carbon radicals from alcohols and offers an approach for the facile and precise construction of all-carbon quaternary centers. The reaction proceeds with a broad substrate scope of alcohols and activated alkenes. It can tolerate a wide range of electrophilic coupling partners, including allylic carboxylates, aryl and vinyl electrophiles, and primary alkyl chlorides/bromides, making the method complementary to the cross-coupling procedures. The method is highly selective for the alkylation of tertiary alcohols, leaving secondary/primary alcohols (benzyl alcohols included) and phenols intact. The synthetic utility of the method is highlighted by its 10-g-scale reaction and the late-stage modification of complex molecules. A combination of experiments and density functional theory calculations establishes a plausible mechanism implicating a tertiary carbon radical generated via Ti-catalyzed homolysis of the C?OH bond.
- Xie, Hao,Guo, Jiandong,Wang, Yu-Quan,Wang, Ke,Guo, Peng,Su, Pei-Feng,Wang, Xiaotai,Shu, Xing-Zhong
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supporting information
p. 16787 - 16794
(2020/11/09)
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- Rapid Deoxyfluorination of Alcohols with N-Tosyl-4-chlorobenzenesulfonimidoyl Fluoride (SulfoxFluor) at Room Temperature
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The deoxyfluorination of alcohols is a fundamentally important approach to access alkyl fluorides, and thus the development of shelf-stable, easy-to-handle, fluorine-economical, and highly selective deoxyfluorination reagents is highly desired. This work describes the development of a crystalline compound, N-tosyl-4-chlorobenzenesulfonimidoyl fluoride (SulfoxFluor), as a novel deoxyfluorination reagent that possesses all of the aforementioned merits, which is rare in the arena of deoxyfluorination. Endowed by the multi-dimensional modulating ability of the sulfonimidoyl group, SulfoxFluor is superior to 2-pyridinesulfonyl fluoride (PyFluor) in fluorination rate, and is also superior to perfluorobutanesulfonyl fluoride (PBSF) in fluorine-economy. Its reaction with alcohols not only tolerates a wide range of functionalities including the more sterically hindered alcoholic hydroxyl groups, but also exhibits high fluorination/elimination selectivity. Because SulfoxFluor can be easily prepared from inexpensive materials and can be safely handled without special techniques, it promises to serve as a practical deoxyfluorination reagent for the synthesis of various alkyl fluorides.
- Guo, Junkai,Kuang, Cuiwen,Rong, Jian,Li, Lingchun,Ni, Chuanfa,Hu, Jinbo
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supporting information
p. 7259 - 7264
(2019/05/10)
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- Catalyst and method for preparing 2-methyl-2,4-pentanediol by diacetone alcohol hydrogenation
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The invention provides a catalyst and a method for preparing 2-methyl-2,4-pentanediol by diacetone alcohol hydrogenation. The method includes that diacetone alcohol and hydrogen are subjected to reaction in the presence of a catalyst to generate 2-methyl-2,4-pentanediol, wherein the catalyst is a supported metal catalyst formed by loading of an active metal component on a hydroxyapatite carrier. The method can be implemented in an environment-friendly solvent as well as under a solvent-free condition, and the conversion rate of diacetone alcohol in preparation of 2-methyl-2,4-pentanediol is up to 100%; a reaction process for preparing 2-methyl-2,4-pentanediol from diacetone alcohol is simple, and simple equipment, simplicity and convenience in operation and mild reaction conditions are realized; the catalyst is simple in preparation and low in cost, large-scale production can be realized, and the catalyst prepared according to an ion exchange method is high in hydrothermal stability and recyclability; reaction products can be easily separated from the catalyst and a solvent system, and short reaction period, suitableness for industrial production and a promising application prospect are realized.
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Paragraph 0053; 0054; 0055; 0056; 0057; 0058; 0059-0080
(2017/10/22)
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- CATALYTIC METHOD OF MANUFACTURE OF COMPOUNDS OF THE DIOL TYPE
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The invention relates to a catalytic method for the industrial production of a diol compound, such as 2-methyl-2-4-pentanediol, also called 2,4-hexylene glycol (HGL), from a β-hydroxy carbonyl compound, Formula (I), in particular diacetone alcohol (DAA).
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Page/Page column 3
(2012/01/13)
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- Extracts of Isochrysis sp.
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The present invention relates to extracts of Isochrysis sp., preferably Tahitian Isochrysis, its cosmetic, dermatological and/or therapeutic uses and compositions and cosmetic, dermatological or therapeutic products comprising such an extract of Isochrysis sp., preferably Tahitian Isochrysis.
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- Extracts of isochrysis sp.
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The present invention relates to extracts of Isochrysis sp., preferably Tahitian Isochrysis, its cosmetic, dermatological and/or therapeutic uses and compositions and cosmetic, dermatological or therapeutic products comprising such an extract of Isochrysis sp., preferably Tahitian Isochrysis.
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- EXTRACTS OF TETRASELMIS SP.
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The present invention relates to extracts of Tetraselmis sp., preferably Tetraselmis suecica, its cosmetic, dermatological and/or therapeutic uses and compositions and cosmetic, dermatological or therapeutic products comprising such an extract of Tetraselmis sp., preferably Tetraselmis suecica.
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- Extracts of Tetraselmis sp. for cosmetic and therapeutic purposes
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The present invention relates to extracts of Tetraselmis sp., preferably Tetraselmis suecica, its cosmetic, dermatological and/or therapeutic uses and compositions and cosmetic, dermatological or therapeutic products comprising such an extract of Tetraselmis sp., preferably Tetraselmis suecica.
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- 1,3-Diol synthesis via controlled, radical-mediated C-H functionalization
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The invention of a method for the synthesis of 1,3-diols from the corresponding alcohols is described, via controlled, radical-mediated C-H functionalization. The sequence described herein entails near quantitative conversion to the corresponding trifluoroethyl carbamate, followed by a variant of the Hofmann-Loffler-Freytag reaction, cyclization, and hydrolysis to provide the 1,3-diols. In addition to the 10 examples presented herein, the syntheses of four natural products are facilitated by this directed oxyfunctionalization. This methodology is demonstrated to be orthogonal to other known C-H oxidations. Finally, this sequence is efficient, practical, inexpensive, and scalable. Copyright
- Chen, Ke,Richter, Jeremy M.,Baran, Phil S.
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p. 7247 - 7249
(2008/12/21)
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- Process for the hydrogenation of acetone
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Acetone is hydrogenated by a process comprising, conducting the liquid-phase hydrogenation of acetone in at least two hydrogenation process stages, thereby preparing isopropanol product with a high selectivity and in high purity.
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Page/Page column 1-2
(2008/06/13)
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- Enantioselective C-C bond formation with titanium(IV) alkoxides - An unusual alkylation
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Mobile hydrogen atoms: The hydrogen atoms of tertiary butyl groups are significantly more mobile than is generally assumed. Under very mild and acidic conditions aldehydes react with Ti(OtBu)4 to form diols in the presence of LiCIO4
- Mahrwald, Rainer
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p. 1361 - 1363
(2007/10/03)
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- Electrophilic reactions of carboyl compounds and derivatives thereof: XIII preparation of bifunctional compounds from aldehydes and olefins by acylation under acidic catalysis
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The reactions of aldehydes and their O-acylated derivatives (α-chloroesters, acylals) with olefins and α-ethoxystyrene in the presence of SnCl4 and ZnCl2 were investigated. The reactions afforded various bifunctional derivatives: diols, hydroxyesters, chloroesters, 1,3-ketoalcohols.
- Luk'yanov,Koblik,Murad'yan
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p. 1593 - 1599
(2007/10/03)
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- Intramolecular H-Transfer Reactions During the Decomposition of Alkylhydroperoxides in Hydrocarbons as the Solvents
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Eight defined primary and secondary alkylhydroperoxides were decomposed in n-alkanes as the solvent, mostly in the presence of manganese stearate.In all cases the corresponding alcohols and carbonyl compounds were formed as the main products with yields of 60-90percent.Besides, difunctional products were formed by an intramolecular H-transfer in the alkoxy radicals corresponding to the starting hydroperoxides.Products possibly formed by an intramolecular H-transfer in the corresponding alkylperoxy radical could be found only in the case of 4-methyl-2-hydroperoxy pentane.The amount of products formed by intramolecular H-transfer depended on the nature of the C-H bond in δ-position to the original hydroperoxy group and lay between 4percent (primary C-H in the case of 4-hydroperoxy heptane) and 13percent (tertiary C-H in the case of 2-hydroperoxy-5-methyl hexane) with respect to the starting hydroperoxide.The amount of products formed by oxidative attack of the alkoxy and alkylperoxy radicals at the normal paraffins used as the solvents was unexpectedly low (always less than 10percent with respect to the starting hydroperoxide).An increment system is proposed for the calculation of 13C-nmr shifts in alkyl hydroperoxides.
- Jinsheng, Li,Pritzkow, Wilhelm,Voerckel, Volkmar
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- Cadmium Chloride-Magnesium-Water: A New System For Reduction of Various Organic Functionalities
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Cadmium chloride-magnesium-THF-water efficiently reduced aldehydes and ketones to their corresponding alcohols, epoxide to mono-alcohol, benzyl halide to toluene, acid chloride to aldehyde and hydrolyzed thioketals to corresponding ketones. Key words: Cadmium chloride-magnesium-THF-H2O, reductions.
- Bordoloi, Manobjyoti
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p. 1681 - 1684
(2007/10/02)
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- AN O-XYLYL DIOL PROTECTING GROUP
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The use of an o-xylyl group as a bridged diol masking group is described.
- Poss, A. J.,Smyth, M. S.
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p. 3363 - 3366
(2007/10/02)
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- Catalysts for alkoxylation reactions
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Catalysts producing a sharply peaked alkoxylation distribution during the alkoxylation of organic materials comprise mixtures of BF3 and metal alkyls or metal alkoxides, SiF4 and metal alkyls or metal alkoxides, or mixtures of these catalysts.
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- Methods of alkoxylation
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Catalysts comprising mixtures of HF and metal alkoxides and mixed metal alkoxides produce a sharply peaked alkoxylation distribution during the alkoxylation of organic materials.
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- Catalysts for alkoxylation reactions
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Catalysts and a method of using said catalysts for the alkoxylation of a variety of materials is disclosed. Catalysts so described produce alkoxylates having a very sharp alkoxylate distribution. The catalysts are supported and unsupported dialkoxy and dialkyl metal fluorides and halides and alkyl metal difluorides and dihalides.
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- METHODS FOR THE INTERCONVERSION OF PROTECTIVE GROUOPS. TRANSFORMATION OF MEM ETHERS INTO ISOPROPYLTHIOMETHYL ETHERS OR CYANOMETHYL ETHERS
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This letter describes methods for the synthesis of isopropylthiomethyl and cyanomethyl ethers from the corresponding MEM ethers and also a process for the cleavage of MEM or MOM ethers of 1,2- and 1,3-diols which avoids cyclization to formals.
- Corey, E. J.,Hua, Duy H.,Seitz, Steven P.
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- DIISOPROPYLSILYL DITRIFLATE AND DI-tert-BUTYLSILYL DITRIFLATE: NEW REAGENTS FOR THE PROTECTION OF DIOLS
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Diisopropylsilyl ditriflate and di-tert-butylsilyl ditriflate, each available from the appropriate dialkylchlorosilane and triflic acid, react with 1,2-, 1,3-, and 1,4-diols usually at 25 deg C in the presence of 2,6-lutidine to provide the corresponding dialkylsilylene derivatives in high yield.These derivatives, which are readily deprotected under mild conditions, can be utilized for selective reactions of polyhydroxy compounds.
- Corey, E. J.,Hopkins, Paul B.
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p. 4871 - 4874
(2007/10/02)
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- COCONDENSATION OF ISOBUTYLENE WITH FORMALDEHYDE AND ACETALDEHYDE
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2,4,4-Trimethyl-1,3-dioxane is formed preferentially in the reaction of isobutylene, formaldehyde, and acetaldehyde in the presence of an acidic catalyst.In addition, 4-dimethyl- and 2,4,4,6-tetramethyl-1,3-dioxanes, 4-methyl-2,4-pentanediol and 3-methyl-1,3-butanediol were found in the reaction mass.The possibility of mutual transformations between the cyclic acetals and formal through the stage of the formation of consecutive-parallel reactions is proposed.
- Safarov, M. G.,Ogorodnikov, S. K.,Ibatullin, U.G.,Idlis, G. S.,Nigmatullin, N. G.
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p. 805 - 809
(2007/10/02)
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