- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- New strategy for production of primary alcohols from aliphatic olefins by tandem cross-metathesis/hydrogenation
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Primary alcohols are widely used in industry as solvents and precursors of detergents. The classic methods for hydration of terminal alkenes always produce the Markovnikov products. Herein, we reported a reliable approach to produce primary alcohols from terminal alkenes combining with biomass-derived allyl alcohol by tandem cross-metathesis/hydrogenation. A series of primary alcohol with different chain lengths was successfully produced in high yields (ca. 90percent). Computational studies revealed that self-metathesis and hydrogenation of substrates are accessible but much slower than cross-metathesis. This new methodology represents a unique alternative to primary alcohols from terminal alkenes.
- Jia, Ruilong,Zuo, Zhijun,Li, Xu,Liu, Lei,Dong, Jinxiang
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p. 1525 - 1529
(2019/11/11)
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- Stabilization of NaBH4 in Methanol Using a Catalytic Amount of NaOMe. Reduction of Esters and Lactones at Room Temperature without Solvent-Induced Loss of Hydride
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Rapid reaction of NaBH4 with MeOH precludes its use as a solvent for large-scale ester reductions. We have now learned that a catalytic amount of NaOMe (5 mol %) stabilizes NaBH4 solutions in methanol at 25 °C and permits the use of these solutions for the reduction of esters to alcohols. The generality of this reduction method was demonstrated using 22 esters including esters of naturally occurring chiral γ-butyrolactone containing dicarboxylic acids. This method permits the chemoselective reductions of esters in the presence of cyano and nitro groups and the reductive cyclization of a pyrrolidinedione ester to a fused five-membered furo[2,3-b]pyrrole and a (-)-crispine A analogue in high optical and chemical yields. Lactones, aliphatic esters, aromatic esters containing electron-withdrawing groups, and heteroaryl esters are reduced more rapidly than aryl esters containing electron-donating groups. The 11B NMR spectrum of the NaOMe-stabilized NaBH4 solutions showed a minor quartet due to monomethoxyborohydride (NaBH3OMe) that persisted up to 18 h at 25 °C. We postulate that NaBH3OMe is probably the active reducing agent. In support of this hypothesis, the activation barrier for hydride transfer from BH3(OMe)- onto benzoic acid methyl ester was calculated as 18.3 kcal/mol.
- Prasanth,Joseph, Ebbin,Abhijith,Nair,Ibnusaud, Ibrahim,Raskatov, Jevgenij,Singaram, Bakthan
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p. 1431 - 1440
(2018/02/09)
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- A Versatile Iridium(III) Metallacycle Catalyst for the Effective Hydrosilylation of Carbonyl and Carboxylic Acid Derivatives
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A versatile iridium(III) metallacycle catalysed rapidly and selectively the reduction of a large array of challenging esters and carboxylic acids as well as various ketones and aldehydes. The reactions proceeded in high yields at room temperature by hydrosilylation followed by desilylation. Although the reactions of various aldehydes and ketones resulted exclusively in alcohols, the hydrosilylation of esters led to alcohols or ethers, depending on the type of substrate. Regarding the carboxylic acids, again the nature of the reagent controlled the outcome of the hydrosilylation reaction, either alcohols or aldehydes being formed.
- Corre, Yann,Rysak, Vincent,Trivelli, Xavier,Agbossou-Niedercorn, Francine,Michon, Christophe
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supporting information
p. 4820 - 4826
(2017/09/07)
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- Reductive removal of methoxyacetyl protective group using sodium borohydride
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Herein, we have developed a mild and selective reductive deprotection method for the MAc protected alcohols using sodium borohydride. The new deprotection conditions provide a complete orthogonality between O-MAc and other protecting groups such as tert-butyl ester, N-Boc, Fmoc, Cbz, O-TBDMS, N-benzyl, O-benzyl, O-acetyl, N-acetyl, N-MAc, etc. In addition to O-MAc deprotection, this method is also applicable for S-MAc deprotection.
- Gadekar, Pradip K.,Hoermann, Maryann,Corbo, Faith,Sharma, Rajiv,Sarveswari,Roychowdhury, Abhijit
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p. 503 - 506
(2014/01/06)
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- The synthesis of one enantiomer of the α-methyl-trans-cyclopropane unit of mycolic acids
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We report the synthesis of a single enantiomer of an α-methyl-trans-cyclopropane unit present in a number of mycolic acids and its incorporation into a reported 1,2-dialkylcyclopropane meromycolate that contains one cis-1,2-dialkylcyclopropane and one α-methyl-trans-1,2-dialkylcyclopropane.
- Al-Dulayymi, Juma'a R.,Baird, Mark S.,Mohammed, Hayder,Roberts, Evan,Clegg, William
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p. 4851 - 4862
(2007/10/03)
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- Ovipositional responses of Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) to natural products from leaves of two maize (Zea mays L.) cultivars
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Ovipositional responses of Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) to hexane extracts of leaves of two maize (Zea mays L.) cultivars, one resistant (Kisan) and one susceptible (Basilocal), were studied in two-choice bioassays. Gravid females laid a significantly higher percentage of eggs on substrates smeared with extract of Basilocal leaves (HEBL) (69%) than on those smeared with extracts of Kisan leaves (HEKL) (31%). Several chemicals were isolated from HEKL, three of which were characterized as dotriacontanol, heptadecanol, and nonadecanol. These chemicals were either absent or were present in very small amounts in HEBL, but in HEKL they were detected in much larger amounts. Each isolated chemical was tested for its effect on C. partellus oviposition in two-choice bioassays. Maximum ovipositional deterrence (90%) was observed for the compound MR-22a, followed in decreasing order by nonadecanol, MR-7, and heptadecanol. The identity of the remaining compounds is being investigated. The results indicate that the relative resistance of Kisan maize compared to Basilocal is partly due to the presence of certain ovipositional deterrents in its leaves.
- Varshney, Anupam K.,Babu, B. Ravindra,Singh, Ashok K.,Agarwal, Hari C.,Jain, Subhash C.
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p. 4008 - 4012
(2007/10/03)
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- New bioactive sulfated metabolites from the Mediterranean tunicate Sidnyum turbinatum
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In addition to the known sodium 3,7,11,15-tetramethylhexadeca-1,19-diyl sulfate (4), the BuOH extract of the Mediterranean tunicate Sidnyum turbinatum was shown to contain four new metabolites: 1-heptadecanyl sulfate (1), 1-octadecanyl sulfate (2), sodium
- Aiello,Carbonelli,Fattorusso,Iuvone,Menna
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p. 219 - 221
(2007/10/03)
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- Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
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A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
- Fullana,Font,Conesa,Blasco
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p. 2092 - 2099
(2007/10/03)
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- Hair growth composition containing citric acid esters
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Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
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- Melting Behaviour of Fatty Alcohols and Their Binary Blends
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The m.p. of pure fatty alcohols from undecyl to nonadecyl are determined along with those of their corresponding pure fatty acids and their methyl esters ; alternation in m.ps. does not occur in fatty alcohol series unlike the other two.Eutectic formation does not take place in the binary blends of fatty alcohols, but a maximum depression of the m.p. of the lower homologue occurs in presence of 11.0 +/- 1.0 mole percent of higher one in the blend.
- Gaikwad, B. R.,Subrahmanyam, V. V. R.
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p. 513 - 515
(2007/10/02)
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