- NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates
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New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(η3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4-trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1-(pyridin-2-yl)propan-2-one provided the β-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.
- Martinez-Espinar, Francisco,Blondeau, Pascal,Nolis, Pau,Chaudret, Bruno,Claver, Carmen,Castillón, Sergio,Godard, Cyril
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p. 113 - 127
(2017/09/08)
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- Diastereo- and enantioselective synthesis of dimethylcyclohexanamines by asymmetric reductive amination
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A series of optically active dimethylcyclohexanamines 6a-c, e, with ee values ranging from 86- > 99%, have been synthesised by asymmetric reductive amination of the corresponding racemic diastereomeric cyclohexanones 3a-c, e. Their conformation and configuration are also discussed.
- Speckenbach,Bisel,Frahm
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p. 1325 - 1330
(2007/10/03)
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- Method for preparing aromatic secondary amino compound
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Disclosed are (1) a method for preparing an aromatic secondary amino compound which comprises reacting an N-cyclohexylideneamino compound in the presence of a hydrogen moving catalyst and a hydrogen acceptor by the use of a sulfur-free polar solvent and/or a cocatalyst, and (2) a method for preparing an aromatic secondary amino compound which comprises reacting cyclohexanone or a nucleus-substituted cyclohexanone, an amine and a nitro compound corresponding to the amine in a sulfur-free polar solvent in the presence of a hydrogen moving catalyst, a cocatalyst being added or not added. In a further aspect, a method is provided for the preparation of aminodiphenylamine by reacting phenylenediamine and cyclohexanone in the presence of a hydrogen transfer catalyst in a sulfur-free polar solvent while using nitroaniline as a hydrogen acceptor.
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- Method for preparing aromatic secondary amino compound
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Disclosed are (1) a method for preparing an aromatic secondary amino compound which comprises reacting an N-cyclohexylideneamino compound in the presence of a hydrogen moving catalyst and a hydrogen acceptor by the use of a sulfur-free polar solvent and/or a cocatalyst, and (2) a method for preparing an aromatic secondary amino compound which comprises reacting cyclohexanone or a nucleus-substituted cyclohexanone, an amine and a nitro compound corresponding to the amine in a sulfur-free polar solvent in the presence of a hydrogen moving catalyst, a cocatalyst being added or not added.
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- Total Synthesis of (+/-)-Pyridoxatin
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An efficient two-step route to pyridoxatin analogues 13 and 15 has been developed.Condensation of 4-hydroxypyridone (4) with citronellal (10) affords o-quinone methide intermediate 11, which reacts further to give inverse electron demand Diels-Alder adducts 12 and 16 and ene adduct 14.Oxidation of 12 and 14 with MoO5 by Sammes' procedure completes the synthesis of 13 and 15.Using this approach, the first total synthesis of (+/-)-pyridoxatin (1) has been carried out in seven steps from cis-2,4-dimethylcyclohexanone (21).The key step is the condensation of 4-hydroxypyridone (4) with the allylic silane aldehyde 26 to give 35percent of cyclohexylpyridones 2 and 30.
- Snider, Barry B.,Lu, Qing
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p. 8065 - 8070
(2007/10/02)
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- Preparation of Optically Pure cis-2,4-Dimethyl-1-cyclohexanones, the Key Intermediates in Cycloheximide Synthesis, Using Microbial Resolution
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Asymmemtric hydrolysis of acetate (10) of (+/-)-t-2,t-4-dimethyl-r-1-cyclohexanol with Bacillus subtilis var. niger gave (-)-(1S,2S,4S)-2,4-dimethyl-1-cyclohexanol (6a) and (+)-(1R,2R,4R)-acetate (10b) with high optical purities.Optically pure (-) and (+)-alcohols (6a and 6b) were prepared via corresponding 3,5-dinitrobenzoates.Oxidation of alcohols (6a and 6b) with chromic acid gave optically pure (-)-(2S,4S) and (+)-(2R,4R)-2,4-dimethyl-1-cyclohexanones (2a and 2b), respectively.
- Oritani, Takayuki,Kudo, Sachio,Yamashita, Kyohei
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p. 757 - 760
(2007/10/02)
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- Polycyclic phenols, alcohols and ketones from phenols, cyclic alcohols and cyclic ketones using a nickel oxide/manganese oxide/magnesium oxide catalyst in presence of at least one of hydrogen and nitrogen
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At least one of a polycyclic phenol, a polycyclic alcohol and a polycyclic ketone is produced under hydrogenation conditions using a nickel oxide/manganese oxide/magnesium oxide catalyst by subjecting at least one of a monocyclic ketone, a monocyclic alcohol and a monocyclic phenol to said conditions and said catalyst.
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