- Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
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Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
- Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
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supporting information
p. 4544 - 4549
(2020/02/04)
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- Iron-Catalyzed Nucleophilic Addition Reaction of Organic Carbanion Equivalents via Hydrazones
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Earth-abundant and well-defined iron complexes are found to be cheap and effective catalysts for a series of "umpolung" nucleophilic additions of hydrazones. The new catalytic system not only maintains the broad substrate scope of an earlier expensive ruthenium system but also attains chemoselectivity of different kinds of carbonyl groups. Furthermore, the iron catalyst enables this reaction at ambient temperature.
- Li, Chen-Chen,Dai, Xi-Jie,Wang, Haining,Zhu, Dianhu,Gao, Jian,Li, Chao-Jun
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p. 3801 - 3805
(2018/07/25)
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- Catalytic C-H activation of phenylethylamines or benzylamines and their annulation with allenes
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Tetrahydro-3-benzazepines and tetrahydroisoquinolines are synthesized in one step from allenes and phenylethylamines or benzylamines, respectively. Mechanistically, it is assumed that activation of a C-H bond of an aromatic ring with Pd(II) occurs, directed by the primary amine, leading to the formation of a palladacycle into which an allene then undergoes insertion. The resulting π-allyl intermediate cyclizes to the products by an intramolecular allylic alkylation. The process is particularly useful with 2,3-butadienoates and amines having a quaternary carbon at the α-position. (Chemical Equation Presented).
- Rodrguez, Aleix,Albert, Joan,Ariza, Xavier,Garcia, Jordi,Granell, Jaume,Farrs, Jaume,La Mela, Andrea,Nicols, Ernesto
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p. 9578 - 9585
(2015/02/19)
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- Oxidative degradation of fragrant aldehydes. Autoxidation by molecular oxygen
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The oxidative degradation of fragrant aldehydes by molecular oxygen has been investigated. The oxygen consumption was monitored and the bond dissociation energy (BDE) of the aldehyde C(O)-H bond were calculated by DFT method. The oxidation products were identified by GC/MS. The different pathways accounting for the oxidative degradation are discussed. The main product is the acid, beside the formate ester. Both oxidation products result from the Baeyer-Villiger reaction involving a peracid R(CO)OOH whereas minor products arise from the hydroperoxide ROOH intermediate derived either from the acyl peroxy radical, R(CO)OO or from the decarboxylation of the peracid RC(O)OOH.
- Marteau,Ruyffelaere,Aubry,Penverne,Favier,Nardello-Rataj
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p. 2268 - 2275
(2013/04/10)
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- Biocatalysed synthesis of the enantiomers of the floral odorant Florhydral
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The two enantiomers of the floral odorant Florhydral were prepared by enzymatic methods, and their olfactory properties were evaluated. (+)-Florhydral was found to be much more powerful than the (-)-enantiomer.
- Abate, Agnese,Brenna, Elisabetta,Dei Negri, Claudia,Fuganti, Claudio,Serra, Stefano
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p. 899 - 904
(2007/10/03)
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