- Carbonylation of dialkylcyanocuprates with carbon monoxide: Synthesis of α-hydroxyketones
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Dialkylcyanocuprates, prepared from copper(I) cyanide and the corresponding alkyllithium or Gringard reagents, readily react with carbon monoxide in the presence of tri-n-butylphosphine at -78°C in THF to give α-hydroxyketones in high yields (65-85%).
- Kabalka, George W.,Li, Nan-Sheng,Yu, Su
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- Synthesis of pentafluorobenzene-based NHC adducts and their catalytic activity in the microwave-assisted reactions of aldehydes
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N-Heterocyclic carbenes (NHCs) have been widely used in organometallic chemistry as ligands, as well as standalone organocatalysts in various reactions, mostly using aromatic aldehydes as substrates. We have previously demonstrated the efficiency of azolium-2-carboxylate zwitterions in the hydroxymethylation of aldehydes, especially aliphatic aldehydes, under microwave irradiation. In the present work, we report a series of pentafluorobenzene-based NHC adducts and their efficiency in the hydroxymethylation and self-condensation of aliphatic and aromatic aldehydes using microwave irradiation. The free carbenes are released under the reaction conditions and 1,3-dimesityl-2-(perfluorophenyl)imidazolidine and 1,3-bis(2,6-dimethylphenyl)-2-(perfluorophenyl)imidazolidine proved to be the most potent precatalysts.
- Papadaki, Evanthia,Magrioti, Victoria
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supporting information
(2019/12/24)
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- NOVEL PROCESS FOR PREPARING SYNTHESIS INTERMEDIATES USING PRODUCTS OF NATURAL ORIGIN AND USE OF THE INTERMEDIATES OBTAINED
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Disclosed is a process for preparing a product of formula I: wherein the reaction is catalyzed both by thiamine or a thiamine salt and by ascorbic acid in a form which is free or salified or an organic acid salt of an alkaline metal, preferably sodium acetate, potassium tartrate, sodium succinate, or a reductone, preferably 2-hydroxypropanedial or 2,3-dihydroxycyclopent-2-ene-1-one in an organic solvent.
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Paragraph 0244-0246
(2017/12/15)
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- Decreasing Side Products and Increasing Selectivity in the Tandem Hydroformylation/Acyloin Reaction
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A highly selective catalyst system was developed for the recently discovered tandem hydroformylation/acyloin reaction by systematic investigations and changes of reaction conditions. This new catalyst system is characterized by an excellent selectivity of the desired reaction pathway with negligible amounts of side products. A successful application of the tandem hydroformylation/acyloin reaction to a variety of olefins is enabled with comparable excellent selectivities up to >99% for the first and second reaction step, therefore a general synthesis for the conversion of olefins into acyloins is found. Furthermore, very good to excellent yields for the intermediates and final acyloin products were observed within two catalysed reactions in one preparative step. The acyloin product was applied as a nonpolar precursor for surfactants. After attaching a polar head group to the acyloin and determination of tensiometric data, the molecule showed industrial relevant surface-active properties. Jointly successful: New catalyst systems for the tandem hydroformylation/acyloin reaction display excellent selectivities within two catalyzed reactions in one preparative step. A variety of olefins can be converted efficiently, and the acyloin product is applied successfully as a nonpolar precursor for surfactants.
- Ostrowski, Karoline A.,Fassbach, Thiemo A.,Vogelsang, Dennis,Vorholt, Andreas J.
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p. 2607 - 2613
(2015/09/15)
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- Tandem hydroformylation/acyloin reaction - The synergy of metal catalysis and organocatalysis yielding acyloins directly from olefins
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A novel, atom efficient, orthogonal tandem catalysis was developed yielding acyloin products (α-hydroxy ketones) directly from olefins under hydroformylation conditions. The combination of a metal-catalysed hydroformylation and an organocatalysed acyloin reaction provides three atom efficient C-C bond formations to linear, multifunctional molecules via linkage of the intermediate n-aldehydes. Additionally, the rhodium catalyst system gives a high n/bra ratio with an exclusive conversion of the terminal double bond in the hydroformylation and the n-aldehydes are converted selectively to their acyloins.
- Ostrowski, Karoline A.,Fassbach, Thiemo A.,Vorholt, Andreas J.
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supporting information
p. 1374 - 1380
(2015/07/07)
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- Product selectivity in the electroreduction of thioesters
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The electroreduction of differently substituted aromatic and aliphatic thioesters (RCOSR′) led to regioselective reactions depending on the nature of the substituents. Thus, the cleavage between the carbonyl group and the SR′ group afforded α-diketones an
- We?wer,Olivero,Du?ach
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p. 1709 - 1714
(2007/10/03)
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- Samarium diiodide promoted formation of 1,2-diketones and 1-acylamido-2-substituted benzimidazoles from N-acylbenzotriazoles
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N-Acylbenzotriazoles, when treated with samarium diiodide in THF, undergo self-coupling reaction to afford 1,2-diketones in good to excellent yields; while when treated with samarium diiodide in CH3CN, they undergo ring-opening reaction to afford 1-acylamido-2-alkyl (or aryl) benzimidazoles in reasonable to good yields. A plausible mechanism was suggested.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 4201 - 4207
(2007/10/03)
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- Formation of 1,2-diketones by samarium diiodide promoted reaction of N-acylbenzotriazoles
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Transformation of N-acylbenzotriazoles 1 into 1,2-diketones 2 in good to excellent yields has been realized by the use of samarium diiodide at room temperature.
- Wang, Xiaoxia,Zhang, Yongmin
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p. 5431 - 5433
(2007/10/03)
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- Ruthenium Tetroxide Oxidation of Alkenes. A More Complete Picture
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The ruthenium tetroxide oxidation of some linear and cyclic alkenes, representatives of five substitution patterns, has been performed in acetone-water (5:1) solution at -70 deg C using stoichiometric ammounts of the oxidant.The main reaction products are 1,2-diols and/or α-ketols depending on the nature of the substrate little amounts of scission products, aldehydes and/or carboxylic acids, are also obtained.Generally 1,2-diols predominate over α-ketols except in the oxidation of (-)-α-pinene that afforded the α-ketol in 51percent yield while no trace of the corresponding 1,2-diol was detected.All reactions prceeded through the formation of unstable brownish precipitates, presumably the intermediate ruthenium (VI) esters, which easily decomposed during the work-up step.Results from oxidation of trans-7-tetradecene and cis and trans-11-tetradecenyl acetate indicated that the reaction was syn stereospecific.In some cases, 1,3-dioxolane products, formed by condensation of the 1,2-diol and the aldehyde materials, were also obtained among the reaction products.Their possible origin is briefly discussed.
- Albarella, Laura,Piccialli, Vincenzo,Sica, Donato,Smaldone, Dina
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p. 2442 - 2456
(2007/10/03)
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- Catalytic action of azolium salts. VI. Preparation of benzoins and acyloins by condensation of aldehydes catalyzed by azolium salts
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Benzoins 4 (2-hydroxyethanones substituted with aryl groups at the 1- and 2-positions) were prepared by self-condensation of aromatic aldehydes 3 using catalytic amounts of azolium salts 1 and 2 in excellent yields. 1,3-Dimethylbenzimidazolium iodide (2) was an effective catalyst for the preparation of acyloins 6 (2-hydroxyethanones substituted with alkyl groups at the 1- and 2-positions) by self-condensation of aliphatic aldehydes 5. On the other hand, an attempt at the condensation of hexanal (5d) catalyzed by 1,3-dimethylimidazolium iodide (1) failed to yield the acyloin 6d, and instead the aldol-type condensed product 8d was obtained.
- Miyashita,Suzuki,Iwamoto,Higashino
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p. 2633 - 2635
(2007/10/02)
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- Photochimie en solution. XXIV. Mecanisme de l'addition des aldehydes aux double liaisons ethyleniques activees par des groupements attracteurs d'electrons
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The mechanism of the photochemical addition of aliphatic aldehydes to electron-deficient olefins has been rationalized.No addition to α,β-unsaturated ketones was observed when the latter were excited.The reaction can be explained by a first self-quenching step of the aliphatic aldehyde involving its lowest triplet state, which is reached with a moderate quantum yield (0.5).The radical R-C.=O produced in the self quenching process adds to the olefin at the more positively-charged carbon atom.The reaction ends by a hydrogen atom exchange between the radical produced by this addition and the radical R-C.HOH.The quantum yield of the product formation is much higher with benzaldehyde owing to the almost unity value of the intersystem crossing, but it competes with the formation of benzile.
- Kawenoki, Isabelle,Maurel, Daniele,Kossanyi, Jean
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p. 385 - 390
(2007/10/02)
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