- Cobalt-Catalyzed Oxygenation/Dearomatization of Furans
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The dearomatization of aromatic compounds using cobalt(II) acetylacetonate with triplet oxygen and triethylsilane converts furans, benzofurans, pyrroles, and thiophenes to a variety of products, including lactones, silyl peroxides, and ketones.
- Oswald, Jonathan P.,Woerpel
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p. 9067 - 9075
(2018/05/29)
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- Hydrogenation of Carbonyl Derivatives with a Well-Defined Rhenium Precatalyst
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The first efficient and general rhenium-catalyzed hydrogenation of carbonyl derivatives was developed. The key to the success of the reaction was the use of a well-defined rhenium complex bearing a tridentate diphosphinoamino ligand as the catalyst (0.5 mol %) at 70 °C in the presence of H2 (30 bar). The mechanism of the reaction was investigated by DFT(PBE0-D3) calculations.
- Wei, Duo,Roisnel, Thierry,Darcel, Christophe,Clot, Eric,Sortais, Jean-Baptiste
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- Hydrogenation of ketones with a manganese PN3P pincer pre-catalyst
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A catalytic hydrogenation of carbonyl derivatives with a manganese pre-catalyst has been developed. The key feature is the use of an air stable cationic manganese pre-catalyst bearing a tridendate ligand with a 2,6-(diaminopyridinyl)diphosphine scaffold. Under 50?bar of H2, at 130?°C, various ketones were reduced to the corresponding alcohols with moderate to good yield.
- Bruneau-Voisine, Antoine,Wang, Ding,Roisnel, Thierry,Darcel, Christophe,Sortais, Jean-Baptiste
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- Direct synthesis of ethers from aldehydes and ketones. One-pot reductive etherification of benzaldehydes, alkyl aryl ketones, and benzophenones
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Benzyl alcohols formed by the reduction of benzaldehydes, alkyl aryl ketones, and benzophenones with sodium tetrahydridoborate in alcohols undergo in situ etherification with the solvent in the presence of a catalytic amount of HCl. Thus the process may be regarded as one-pot transformation of carbonyl compounds into the corresponding benzyl ethers. The yields of ethers depend on the substituent nature in the aromatic fragment of the initial carbonyl compound and on the alcohol used as reduction medium.
- Mochalov,Fedotov,Trofimova,Zefirov
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p. 503 - 512
(2016/06/13)
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- Ansa-Ruthenium(II) Complexes of R2NSO2DPEN-(CH2)n(η6-Aryl) Conjugate Ligands for Asymmetric Transfer Hydrogenation of Aryl Ketones
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New 3rd generation designer ansa-ruthenium(II) complexes featuring N,C-alkylene-tethered N,N-dialkylsulfamoyl-DPEN/η6-arene ligands, exhibited good catalytic performance in the asymmetric transfer hydrogenation (ATH) of various classes of (het)aryl ketones in formic acid/triethylamine mixture. In particular, benzo-fused cyclic ketones furnished 98 to >99.9% ee using a low catalyst loading.
- Ki?ic, Andrea,Stephan, Michel,Mohar, Barbara
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supporting information
p. 2540 - 2546
(2015/08/18)
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- Highly enantioselective synthesis of heteroaromatic alcohols catalyzed by chiral diaminodiphosphine-ruthenium(II) complexes
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Chiral diaminodiphosphine-ruthenium(II) complexes were found to be excellent catalysts for the asymmetric transfer hydrogenation of heteroaromatic ketones in propan-2-ol. In the presence of potassium hydroxide, the enantioselective reduction of heteroaromatic ketones proceeded smoothly to give chiral alcohols with excellent enantiomeric excess (up to 97% ee) under mild conditions without reduction of the heterocycle. Georg Thieme Verlag Stuttgart.
- Shen, Wei-Yi,Li, Yan-Yun,Dong, Zhen-Rong,Gao, Jing-Xing
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experimental part
p. 2413 - 2417
(2010/01/19)
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- Chiral spiroaminoborate ester as a highly enantioselective and efficient catalyst for the borane reduction of furyl, thiophene, chroman, and thiochroman-containing ketones
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Prochiral heteroaryl ketones containing furan, thiophene, chroman, and thiochroman moieties were successfully reduced in the presence of 1-10 mol % of spiroaminoborate ester 1 with different borane sources to afford non-racemic alcohols in up to 99% ee. In addition, modest enantioselectivity, around 80% ee, was achieved in the reduction of linear α,β-unsaturated heteroaryl ketones.
- Stepanenko, Viatcheslav,De Jesus, Melvin,Correa, Wildeliz,Bermudez, Lorianne,Vazquez, Cindybeth,Guzman, Irisbel,Ortiz-Marciales, Margarita
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experimental part
p. 2659 - 2665
(2010/04/29)
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- Synthesis of a 2,7-dioxatricyclo[4.2.1.03,8]nonane: A model study for possible application in a synthesis of dictyoxetane
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A method for the synthesis of the 2,7-dioxatricyclo[4.2.1.03,8]nonane ring system characteristic of the marine diterpene dictyoxetane has been developed. This method utilizes a dipolar cycloaddition of a 3-oxidopyrylium salt to create the carbon skeleton and employs an intramolecular S(N)2 displacement to form the oxetane ring. The route described could easily be adapted to incorporate additional functionality, making it potentially useful in a total synthesis of dictyoxetane.
- Marshall,Mapp,Heathcock
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p. 9135 - 9145
(2007/10/03)
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- INTRAMOLECULAR DIELS-ALDER REACTION OF FURANS WITH ALLENYL ETHERS : HIGH EFFECT OF THE CHAIN LENGTH ON THE STRUCTURE AND REACTIVITY OF THE CYCLOADDUCTS
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The structure and reactivity of the cycloadducts of the title reaction were found to be highly dependent on the chain length between the furan diene and the allenyl ether dienophile.Reaction of the propargyl ether (2) with t-BuOK in the t-BuOH at 85 deg C for 3 h gave a mixture of the cycloadducts (3) and (4) in 90percent yield, which were transferred to the benzo derivatives (5), (6) and (7).Treatment of the propargyl ether (8) with t-BuOK in t-BuOH at 85 deg C for 5 h gave the products (9) and (10) in a ratio of 8:1 in 65 percent yield, no detectable amount of the cycloadduct (8b) was obtained.Refluxing of the propargyl ether (13) with t-BuOK in t-BuOH at 85 deg C for 4 h gave the allenyl ether (14).Heating 14 in DMSO at 150 deg C for 12 h still did not give 15.
- Wu, Hsien-Jen,Lin, Shie-Hsiung,Lin, Chu-Chung
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p. 1507 - 1518
(2007/10/02)
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