- Deprotonation des allylbenzenes chrometricarbonyle en milieu basique. Etude RMN 1H et 13C et reactivite des anions allyliques: influence electronique et sterique du groupement chrometricarbonyle
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1H and 13C NMR study of allylic anions obtained in basic media from allylbenzene Cr(CO)3 and propenylbenzene Cr(CO)3 or 2 is reported.A comparison with uncomplexed anions literature results allows to specify the structure of the anion and the ele
- Senechal-Tocquer, M.C.,Senechal, D.,Bihan, J.Y. Le,Gentric, D.,Caro, B.,et al.
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Read Online
- Direct and Unified Access to Carbon Radicals from Aliphatic Alcohols by Cost-Efficient Titanium-Mediated Homolytic C?OH Bond Cleavage
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Low-valent Ti-mediated homolytic C?O bond cleavage offers unified access to carbon radicals from ubiquitous non-activated tertiary, secondary, and even primary alcohols. In contrast to the representative Ti reagents, which were ineffective for this purpos
- Suga, Takuya,Takahashi, Yuuki,Miki, Chinatsu,Ukaji, Yutaka
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supporting information
(2022/01/31)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Homoleptic cobalt(II) phenoxyimine complexes for hydrosilylation of aldehydes and ketones without base activation of cobalt(II)
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Air-stable, easy to prepare, homoleptic cobalt(II) complexes bearing pendant-modified phenoxyimine ligands were synthesized and determined. The complexes exhibited high catalytic performance for reducing aldehydes and ketones via catalytic hydrosilylation, where a hydrosilane and a catalytic amount of the cobalt(II) complex were added under base-free conditions. The reaction proceeded even in the presence of excess water, and excellent functional-group tolerance was observed. Subsequent hydrolysis gave the alcohol in high yields. Moreover, H2O had a critical role in activation of the Co(II) catalyst with hydrosilane. Several additional results also indicated that the cobalt(II) center acts as an active catalyst in the hydrosilylation of aldehydes and ketones.
- Hori, Momoko,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki,Mitsuyama, Tomoaki,Shin, Sayaka
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supporting information
p. 1379 - 1387
(2021/05/29)
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- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
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Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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supporting information
p. 8738 - 8741
(2021/09/08)
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- 1-D manganese(ii)-terpyridine coordination polymers as precatalysts for hydrofunctionalisation of carbonyl compounds
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Reductive catalysis with earth-abundant metals is currently of increasing importance and shows potential in replacing precious metal catalysis. In this work, we revealed catalytic hydroboration and hydrosilylation of ketones and aldehydes achieved by a structurally defined manganese(ii) coordination polymer (CP) as a precatalyst under mild conditions. The manganese-catalysed methodology can be applied to a range of functionalized aldehydes and ketones with turnover numbers (TON) of up to 990. Preliminary results on the regioselective catalytic hydrofunctionalization of styrenes by the Mn-CP catalyst are also presented.
- Johnson, Jahvon,Li, Sihan,Mo, Zixuan,Neary, Michelle C.,Zeng, Haisu,Zhang, Guoqi,Zheng, Shengping
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supporting information
p. 2610 - 2615
(2020/03/05)
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- Erratum: Redox-Noninnocent Ligand-Supported Vanadium Catalysts for the Chemoselective Reduction of C=X (X = O, N) Functionalities (Journal of the American Chemical Society (2019) 141:38 (15230-15239) DOI: 10.1021/jacs.9b07062)
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Pages 15232, 15233, and 15236. In the original paper, the doublet wave functions for 21 and 21a/21b were incorrectly (Figure Presented). reported as spin-contaminated in sections 2.3 and 2.8 (Figure 3 and Scheme 9, respectively.) This comes from the incorrectly reported expected eigenvalue of 0.75 for the spin-squared operator ??2? for the antiferromagnetically coupled doublet |↓?L|↑↑?V state (originally given in the Supporting Information). The correct expected eigenvalue for the |↓?L|↑↑?V state should be 1.75. The wave functions for 21 and 21a/21b (eigenvalues 1.79 and 1.77/1.66, respectively) are therefore not spincontaminated. The corrected Figure 3 and Scheme 9 are presented below. A corrected Supporting Information file is also provided. The corrections do not affect any of the conclusions of the Article, but slightly decrease the gap between the quartet and doublet spin surfaces. Scheme 3 has been also corrected to reflect the fact that (CH3)3SiCH2 ? radicals can only react based on spin conservation.
- Zhang, Guoqi,Wu, Jing,Zheng, Shengping,Neary, Michelle C.,Mao, Jincheng,Flores, Marco,Trovitch, Ryan J.,Dub, Pavel A.
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supporting information
p. 16507 - 16509
(2020/10/14)
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- Diboron-Mediated Rhodium-Catalysed Transfer Hydrogenation of Alkenes and Carbonyls
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A diboron-mediated rhodium-catalysed transfer hydrogenation system using water as the hydrogen donor is developed. In addition to a series of alkenes with good functional group tolerance, this rhodium-based catalytic system also effectively reduces aldehydes and ketones. A plausible mechanism involving the RhI-catalysed hydrogen generation and Rh0-catalysed hydrogenation is proposed for the reaction.
- Lin, Xiao,Wang, Yuhan,Hu, Yan,Zhu, Wanjiang,Dou, Xiaowei
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supporting information
p. 1046 - 1049
(2020/02/25)
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- Efficient Transfer Hydrogenation of Ketones using Methanol as Liquid Organic Hydrogen Carrier
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Herein, we demonstrate an efficient protocol for transfer hydrogenation of ketones using methanol as practical and useful liquid organic hydrogen carrier (LOHC) under Ir(III) catalysis. Various ketones, including electron-rich/electron-poor aromatic ketones, heteroaromatic and aliphatic ketones, have been efficiently reduced into their corresponding alcohols. Chemoselective reduction of ketones was established in the presence of various other reducible functional groups under mild conditions.
- Garg, Nidhi,Paira, Soumen,Sundararaju, Basker
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p. 3472 - 3476
(2020/05/29)
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- Heteroditopic Ru(II)-And Ir(III)-NHC Complexes with Pendant 1,2,3-Triazole/Triazolylidene Groups: Stereoelectronic Impact on Transfer Hydrogenation of Unsaturated Compounds
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Imidazol-2-ylidene (ImNHC) and 1,2,3-Traizol-5-ylidene (tzNHC) have been established as important classes of carbene ligands in homogeneous catalysis. To develop Ru(II)/Ir(III) complexes based on these ligand systems considering their electronic as well as steric profiles for hydride transfer reactions, we employed chelating ligands featuring combinations of ImNHC and triazole-N or mesoionic tzNHC donors bridged by a CH2 spacer with possible modifications at triazole backbone. In general, synthesized Ru(II) complexes were found to perform significantly better than analogous Ir(III) complexes in ketone and aldimine reduction. Among the Ru(II) complexes, electron-rich complexes 8/9 of the general formula [(p-cymene)(ImNHC-CH2-TzNHC)RuII(Cl)]BF4 with two different carbene donors (ImNHC and tzNHC) were found to perform appreciably better in ketone reduction than analogous complexes with a combination of ImNHC and triazole-N-donor ([(p-cymene)(ImNHC-CH2-Tz-N)RuII(Cl)]BF4; 4) explaining the electronic fine-Tuning of the catalytic systems. No appreciable variation in activity was observed between complexes 8 and 9 having almost similar electronic profiles. However, less bulky Ru(II) complex 9 with a triazole N-phenyl substituent is more suitable for aldimine reduction than is complex 8, having a triazole N-3,5-dimethylphenyl substituent that explains the steric influence in addition to electronic effect on the reduction process.
- Illam, Praseetha Mathoor,Donthireddy,Chakrabartty, Sayantan,Rit, Arnab
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supporting information
p. 2610 - 2623
(2019/07/31)
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- Design of Manganese Phenol Pi-complexes as Shvo-type Catalysts for Transfer Hydrogenation of Ketones
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Catalytic hydrogenation is one of the most important reactions both in academic research and industry. We explored ability of the manganese pi-complexes to act as Shvo-type catalysts for transfer hydrogenation of ketones. DFT calculations suggested that the transfer of hydrogen atoms from the hypothetical intermediate [(C6Me3H2OH)Mn(CO)2H] to acetone has low activation barrier of 10.9 kcal mol?1. Experimentally a number of ketones with various functional groups (OMe, NH2, Cl, CF3, pyridyl) were successfully reduced in isopropanol at 90 °C in the presence of the complex [(C6Me3H2OH)Mn(CO)3]BF4 (1 mol %) and tBuOK (75 mol %). However, further investigation revealed that the reduction was mainly promoted by base rather than the manganese complex.
- Shvydkiy, Nikita V.,Vyhivskyi, Oleksandr,Nelyubina, Yulia V.,Perekalin, Dmitry S.
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p. 1602 - 1605
(2019/03/07)
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- Dearomatization and Functionalization of Terpyridine Ligands Leading to Unprecedented Zwitterionic Meisenheimer Aluminum Complexes and Their Use in Catalytic Hydroboration
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This paper reports the first example of dearomatization of ubiquitous terpyridine (tpy) ligands via 2′/6′-, 3′/5′-, or 4′-selective alkylation of the central pyridine ring. The reaction is mediated by the most abundant metal in the Earth's crust, aluminum (Al), and depending on the conditions employed, exhibits ionic or radical character as suggested by experimental and computational analysis. In the latter case, intermediate formation of an AlIII complex supported by π-radical monoanionic ligand (tpy?)1- is apparent. The 3′/5′-alkylation leads to unprecedented zwitterionic Meisenheimer AlIII complexes, which were identified as efficient precatalysts for the selective hydroboration of C=O and C-C functionalities. Turnover numbers (TONs) up to ~1000 place the corresponding complexes in the category of the most efficient Al catalysts reported to date for the title reaction. The acquired data suggest that aluminum monohydrides, or more likely dihydrides, could be relevant catalytic species. Alternatively, one can also imagine a mechanistic scenario in which the dearomatized "chemically noninnocent" ligand acts as hydride donor, and a detailed investigation of this is warranted in the future.
- Zhang, Guoqi,Wu, Jing,Zeng, Haisu,Neary, Michelle C.,Devany, Matthew,Zheng, Shengping,Dub, Pavel A.
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p. 874 - 884
(2019/01/14)
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- Mild and efficient rhodium-catalyzed deoxygenation of ketones to alkanes
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A new and simple method for the deoxygenation of ketones to alkanes is presented. Most substrates are reduced under mild conditions by triethylsilane in the presence of catalytic amounts of [Rh(μ-Cl)(CO)2]2. This system selectively provides the methylene hydrocarbons in good to excellent yields starting from acetophenones and diaryl ketones. A rapid examination of the reaction pathway suggests that the ketone is first converted into an alcohol, which then undergoes hydrogenolysis to give the alkane.
- Argouarch, Gilles
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supporting information
p. 11041 - 11044
(2019/07/31)
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- A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
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Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
- Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
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supporting information
p. 1552 - 1566
(2019/06/14)
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- Dehalogenative Deuteration of Unactivated Alkyl Halides Using D2O as the Deuterium Source
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The general dehalogenation of alkyl halides with zinc using D2O or H2O as a deuterium or hydrogen donor has been developed. The method provides an efficient and economic protocol for deuterium-labeled derivatives with a wide substrate scope under mild reaction conditions. Mechanistic studies indicated that a radical process is involved for the formation of organozinc intermediates. The facile hydrolysis of the organozinc intermediates provides the driving force for this transformation.
- Xia, Aiyou,Xie, Xin,Hu, Xiaoping,Xu, Wei,Liu, Yuanhong
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p. 13841 - 13857
(2019/10/17)
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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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- Cobalt(II) Coordination Polymer as a Precatalyst for Selective Hydroboration of Aldehydes, Ketones, and Imines
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Highly effective hydroboration precatalyst is developed based on a cobalt(II)-terpyridine coordination polymer (CP). The hydroboration of ketones, aldehydes, and imines with pinacolborane (HBpin) has been achieved using the recyclable CP catalyst in the presence of an air-stable activator. A wide range of substrates containing polar C=O or C=N bonds have been hydroborated selectively in excellent yields under ambient conditions.
- Wu, Jing,Zeng, Haisu,Cheng, Jessica,Zheng, Shengping,Golen, James A.,Manke, David R.,Zhang, Guoqi
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p. 9442 - 9448
(2018/07/05)
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- Highly efficient hydroboration of carbonyl compounds catalyzed by tris(methylcyclopentadienyl)lanthanide complexes
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Homoleptic lanthanide complexes coordinated by a Me-substituted Cp ligand [(MeCp)3Ln] demonstrate unprecedentedly high efficiency in catalyzing the hydroboration of aldehydes and ketones with pinacolborane. This protocol is also applicable for the hydroboration of aryl-substituted imines. In addition, broad functional group compatibility and excellent chemoselectivity is also achieved. DFT calculations are employed to shed light on the reaction mechanism.
- Yan, Dandan,Dai, Ping,Chen, Sufang,Xue, Mingqiang,Yao, Yingming,Shen, Qi,Bao, Xiaoguang
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p. 2787 - 2791
(2018/04/27)
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- Iron(ii) coordination polymer catalysed hydroboration of ketones
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Catalytic hydroboration of ketones with pinacolborane was achieved with a 2D iron(ii) coordination polymer (CP) of a divergent 4,2′;6′,4′′-terpyridine (tpy) derivative under mild conditions with high efficiency. This solid iron catalyst system is more active towards the hydroboration of ketones than that of aldehydes, displaying a different trend of reactivity from known homogeneous iron hydroboration catalysts.
- Li, Li,Liu,Cheng, Jessica,Zhang, Guoqi
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supporting information
p. 9579 - 9584
(2018/08/06)
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- Homoleptic iron(II) and cobalt(II) bis(phosphoranimide) complexes for the selective hydrofunctionalization of unsaturated molecules
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Low-coordinate homoleptic bulky M2(NPtBu3)4 (M = Fe (A), Co (B)) complexes were synthesized and characterized as dimeric structures by crystallographic studies. The iron complex A can catalyze the hydroboration reaction of aldehydes and ketones. The cobalt complex B outperformed its iron counterpart in hydrogenations of several typical alkenes and alkynes under mild conditions. Poisoning experiments indicate that the Co(ii)/HBpin catalytic system could be homogeneous.
- Bai, Tao,Janes, Trevor,Song, Datong
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supporting information
p. 12408 - 12412
(2017/10/06)
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- Pure phosphotriesters as versatile ligands in transition metal catalysis: efficient hydrosilylation of ketones and diethylzinc addition to aldehydes
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This work aims to highlight the underrated role played by pure phosphotriester (or phosphate) ligands in catalysis, when compared to other phosphorus-containing donors such as phosphane oxides or phosphites. To probe this and to enlarge the very narrow catalytic scope of these Lewis bases, easily accessible mono- and bidentate phosphotriesters were tested as donors in two important transition metal-based catalytic transformations: the zinc-catalyzed hydrosilylation of ketones and the titanium-promoted diethylzinc addition to aldehydes. In both cases, the reactions were successful and the corresponding alcohols were obtained in high yields.
- Bouhachicha,Ngo Ndimba,Roisnel,Lalli,Argouarch
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p. 4767 - 4770
(2017/07/11)
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- Alkene Metalates as Hydrogenation Catalysts
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First-row transition-metal complexes hold great potential as catalysts for hydrogenations and related reductive reactions. Homo- and heteroleptic arene/alkene metalates(1?) (M=Co, Fe) are a structurally distinct catalyst class with good activities in hydrogenations of alkenes and alkynes. The first syntheses of the heteroleptic cobaltates [K([18]crown-6)][Co(η4-cod)(η2-styrene)2] (5) and [K([18]crown-6)][Co(η4-dct)(η4-cod)] (6), and the homoleptic complex [K(thf)2][Co(η4-dct)2] (7; dct=dibenzo[a,e]cyclooctatetraene, cod=1,5-cyclooctadiene), are reported. For comparison, two cyclopentadienylferrates(1?) were synthesized according to literature procedures. The isolated and fully characterized monoanionic complexes were competent precatalysts in alkene hydrogenations under mild conditions (2 bar H2, r.t., THF). Mechanistic studies by NMR spectroscopy, ESI mass spectrometry, and poisoning experiments documented the operation of a homogeneous mechanism, which was initiated by facile redox-neutral π-ligand exchange with the substrates followed by H2 activation. The substrate scope of the investigated precatalysts was also extended to polar substrates (ketones and imines).
- Büschelberger, Philipp,G?rtner, Dominik,Reyes-Rodriguez, Efrain,Kreyenschmidt, Friedrich,Koszinowski, Konrad,Jacobi von Wangelin, Axel,Wolf, Robert
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p. 3139 - 3151
(2017/03/13)
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- Highly Selective Hydroboration of Alkenes, Ketones and Aldehydes Catalyzed by a Well-Defined Manganese Complex
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Well-defined manganese complexes based on inexpensive, readily available ligands, 2,2′:6′,2′′-terpyridine and its derivatives have been prepared and employed for the selective hydroboration of alkenes, ketones and aldehydes. Highly Markovnikov regioselective hydroboration of styrenes as well as excellent chemoselective hydroboration of ketones over alkenes were achieved, for the first time, by an earth-abundant manganese catalyst.
- Zhang, Guoqi,Zeng, Haisu,Wu, Jing,Yin, Zhiwei,Zheng, Shengping,Fettinger, James C.
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supporting information
p. 14369 - 14372
(2016/11/11)
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- MONOMERS FOR USE IN A POLYMERIZABLE COMPOSITION AND HIGH REFRACTIVE INDEX POLYMER FOR OPTHALMIC APPLICATIONS
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Provided are monomers of formula (I), polymerizable compositions comprising the monomer of formula (I) optionally together with other co-polymerizable monomers and polymers obtained or obtainable from the polymerizable compositions, where the monomer of f
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Paragraph 0300-0302
(2016/08/07)
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- Cyclopentadienyliron dicarbonyl dimer: A simple tool for the hydrosilylation of aldehydes and ketones under air
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The readily available iron complex [CpFe(CO)2]2 (1) exhibits good catalytic activity in the hydrosilylation of aldehydes and ketones in the presence of diethoxymethylsilane. The procedure described is air-tolerant and applicable to a wide range of substrates.
- Jung, Thais Cordeiro,Argouarch, Gilles,Van De Weghe, Pierre
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- Ruthenium Catalyzed Selective Hydroboration of Carbonyl Compounds
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Using the [Ru(p-cymene)Cl2]2 (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [{(μ6-p-cymene)RuCl}2(μ-H-μ-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.
- Kaithal, Akash,Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 4790 - 4793
(2015/10/12)
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- A one-pot C-H insertion/olefination sequence for the formation of α-alkylidene-γ-butyrolactones
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A one-pot C-H insertion/olefination sequence for the conversion of α-diazo-α-(dialkoxyphosphoryl)acetates into α-alkylidene- γ-butyrolactones is reported. The key C-H insertion process is achieved using a catalytic amount of a dirhodium carboxylate cataly
- Lloyd, Matthew G.,Taylor, Richard J. K.,Unsworth, William P.
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supporting information
p. 2772 - 2775
(2014/06/09)
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- Heteroatom-free arene-cobalt and arene-iron catalysts for hydrogenations
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75 years after the discovery of hydroformylation, cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. We have evaluated arene metalates in which the low-valent metal species is - conceptually different from heteroatom-based ligands - stabilized by π coordination to hydrocarbons. Potassium bis(anthracene)cobaltate 1 and -ferrate 2 can be viewed as synthetic precursors of quasi-"naked" anionic metal species; their aggregation is effectively impeded by (labile) coordination to the various π acceptors present in the hydrogenation reactions of unsaturated molecules (alkenes, arenes, carbonyl compounds). Kinetic studies, NMR spectroscopy, and poisoning studies of alkene hydrogenations support the formation of a homogeneous catalyst derived from 1 which is stabilized by the coordination of alkenes. This catalyst concept complements the use of complexes with heteroatom donor ligands for reductive processes. Especially high selectivities were observed in the hydrogenation of various alkenes, ketones, and imines with bis(anthracene) cobaltate(-I) [K(dme)2{Co(C14H10)2}] under mild conditions (1-5 mol% cat., 1-10 bar H2, 20-60°C). Mechanistic studies indicate the operation in alkene hydrogenations of a homogeneous catalyst formed by initial ligand exchange and stabilized by the coordination of π-acidic alkenes or arenes.
- Gaertner, Dominik,Welther, Alice,Rad, Babak Rezaei,Wolf, Robert,Von Wangelin, Axel Jacobi
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supporting information
p. 3722 - 3726
(2014/04/17)
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- Catalyst-controlled highly selective coupling and oxygenation of olefins: A direct approach to alcohols, ketones, and diketones
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Oxygen? That's radical! A method for the direct synthesis of substituted alcohols, ketones, and diketones through a catalyst-controlled highly chemoselective coupling and oxygenation of olefins has been developed. The method is simple and practical, can be switched by the selection of different catalysts, and employs molecular oxygen as both an oxidant and a reagent. Copyright
- Su, Yijin,Sun, Xiang,Wu, Guolin,Jiao, Ning
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supporting information
p. 9808 - 9812
(2013/09/23)
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- Catalytic hydrosilylation of ketones using a Co/Zr heterobimetallic complex: Evidence for an unusual mechanism involving ketyl radicals
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The tris(phosphinoamide)-linked heterobimetallic Co/Zr complex (THF)Zr(MesNPiPr2)3CoN2 (1) has been investigated as a catalyst for the hydrosilylation of ketones with PhSiH 3. Catalytic activity superior to monometallic Co or Zr analogues has been observed, demonstrating the importance of cooperative reactivity between Co and Zr. Upon examining stoichiometric reactions, complex 1 was found to be unreactive toward PhSiH3, implying that the mechanism diverges from the typical Chalk-Harrod-type hydrosilylation pathway. In contrast, 1 reacts readily with ketones, and in the case of benzophenone, a radical coupling product [(Ph2CO)Zr(MesNPiPr2) 3CoN2]2 (3) was isolated, implying the intermediacy of a Zr-bound ketyl radical fragment. A radical-based hydrosilylation mechanism is proposed involving hydrogen atom transfer from PhSiH3 to the Zr-bound ketyl-radical.
- Zhou, Wen,Marquard, Seth L.,Bezpalko, Mark W.,Foxman, Bruce M.,Thomas, Christine M.
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p. 1766 - 1772
(2013/05/08)
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- (N -Phosphinoamidinate)Iron pre-catalysts for the room temperature hydrosilylation of carbonyl compounds with broad substrate scope at low loadings
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The synthesis and structural characterization of three-coordinate iron(II) and cobalt(II) complexes supported by new N-phosphinoamidinate ligands is reported, along with the successful application of these complexes as precatalysts for the challenging room-temperature hydrosilylation of carbonyl compounds to afford alcohols upon workup. Under the rigorous screening conditions employed (0.015 mol % Fe) for the reduction of acetophenone, the well-defined iron(II) amido precatalyst 2b, featuring bulky N-2,6- diisopropylphenyl and di-tert-butylphosphino moieties within the N-phosphinoamidinate ligand, exhibited exceptional catalytic performance. Further experimentation revealed that the yield achieved in the hydrosilylation of acetophenone employing 2b was unaltered when conducting reactions in the absence of light, in the presence of excess mercury, or under solvent-free conditions. Notably, precatalyst 2b was found to exhibit the broadest substrate scope reported to date for such room-temperature iron-catalyzed carbonyl hydrosilylations en route to alcohols, enabling the chemoselective reduction of structurally diverse aldehydes and ketones, as well as for the first time esters, at remarkably low loadings (0.01-1.0 mol % Fe) and using only 1 equiv of phenylsilane reductant.
- Ruddy, Adam J.,Kelly, Colin M.,Crawford, Sarah M.,Wheaton, Craig A.,Sydora, Orson L.,Small, Brooke L.,Stradiotto, Mark,Turculet, Laura
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supporting information
p. 5581 - 5588
(2013/11/06)
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- Iron dihydride complex as the pre-catalyst for efficient hydrosilylation of aldehydes and ketones under visible light activation
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A general and efficient hydrosilylation of aldehydes and ketones into the corresponding alcohols using the well-defined bis(diphenylphosphinoethane)iron dihydride complex as the pre-catalyst is reported using polymethylhydrosiloxane (PMHS) as the reducing silylating agent and sodium tetraethoxyborate [NaB(OEt)4] as a co-catalyst under visible light irradiation. The low catalyst loadings (0.1-1 mol%), the amount of economical hydride source, PMHS and the unconventional way of activation of the pre-catalyst make this new approach attractive.
- Castro, Luis C. Misal,Bezier, David,Sortais, Jean-Baptiste,Darcel, Christophe
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supporting information; experimental part
p. 1279 - 1284
(2011/06/26)
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- Sm(II)-mediated reduction in water: Importance of the additive in the proportionation of SmCl3 and Sm
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Mechanistic studies of the SmCl3-Sm system in water were carried out. The addition of N,N-dimethylacetoamide (DMA) enhanced the reactivity of the one-electron reduction. According to the ultraviolet-visible (UV-vis) analysis, DMA was found to accelerate proportionation of SmCl3 and Sm.
- Matsukawa,Ichikawa,Ogura
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experimental part
p. 1345 - 1349
(2010/07/02)
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- The first asymmetric halogen/metal-exchange reaction: Desymmetrization of alcohols with enantiotopic bromoarene substituents
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Desymmetrizations of the prochiral bis(bromoaryl)alcohols 1 and 4 were effected by treatment with iPr2Mg and enantiomerically pure lithium alkoxides. The resulting arylmagnesium compounds were quenched with various electrophiles. The absolute and (if relevant) relative configurations of the resulting products were determined. The best ee/yield combination was obtained for the protonolysis furnishing monobromoalcohol (R)-2 (53% ee, 51% yield). The latter was converted into (R)-orphenadrine, an antihistaminic and anticholinergic drug.
- Saelinger, Daniel,Brueckner, Reinhard
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experimental part
p. 6688 - 6703
(2010/02/28)
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- Acid-, water- and high-temperature-stable ruthenium complexes for the total catalytic deoxygenation of glycerol to propane
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The ruthenium aqua complexes [Ru(H2O)2(bipy) 2](OTf)2, [cisRu(6,6′-Cl2-bipy) 2(OH2O)2)] (OTf)2, [Ru(H 2O)2(phen)2](OTf)2, [Ru(H 2O)3(2,2′:6′,2″-terpy)](OTf) 2 and [Ru(H2O)3(Phterpy)] (OTf)2 (bipy = 2,2′-bipyridine; OTf- = triflate; phen = phenanthroline; terpy = terpyridine; Phterpy = 4′-phenyl-2,2′: 6′,2″-terpyridine) are water- and acid-stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)2CF3 (triflic acid) as a dehydration co-catalyst they directly convert 1,2-hexanediol to n-hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures ≥ 250°C and in either aqueous sulfolane solution or pure water convert glycerol into n-propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4′-R-2,2′:6′,2″-terpy)Ru(CO) (H2O)2]-(OTf)2 (R = H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2-hexanediol and 3-hydroxypropanal for glycerol) generated in the reaction mixture through acid-catalyzed dehydration. The structure of the dimeric complex [{(4′-phenyl-2,2′: 6′,2″-terpy)Ru(CO)}2(μ-OCH3) 2](OTf)2 has been determined by single crystal X-ray crystallography (Space group P1 (a = 8.2532(17); b = 12.858(3); C = 14.363(3) A; α = 64.38(3); β = 77.26(3); γ = 87.12(3)°, R = 4.36%).
- Taher, Deeb,Thibault, Michelle E.,Di Mondo, Domenico,Jennings, Michael,Schlaf, Marcel
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supporting information; experimental part
p. 10132 - 10143
(2010/04/03)
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- Solvolysis of benzyl alcohols and ethers in 1,2-diols and application to a deprotection of benzyl ether-type protecting groups
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Some kinds of benzyl alcohols and ethers react with 1,2-diols, such as ethylene glycol and propylene glycol, at 130-190°C to give 2-hydroxyethyl or 2-hydroxypropyl ethers. Application of this reaction to a deprotection of benzyl ether-type protecting groups, under neutral conditions, was also described. Copyright
- Miyake, Hideyoshi,Fujimura, Masahiro,Tsumura, Takatsugu,Sasaki, Mitsuru
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p. 778 - 779
(2007/10/03)
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- A new mixed P,S-bidentate ligand featuring a λ4- phosphinine anion and a phosphanyl sulfide group - Synthesis, x-ray crystal structures and catalytic properties of its chloro(cymene)ruthenium and allylpalladium complexes
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1,3,2-Diazaphosphinine (1) reacts successively with diphenylacetylene and diphenyl(1-propynyl)phosphane sulfide to afford the P,S-bidentate phosphinine 3. Reaction of nBuLi with 3 followed by complexation with [RuCl2(C 10H14)]2 gave two diastereoisomers 5a,b. Variable-temperature NMR spectroscopy and ONIOM DFT calculations were carried out to rationalize their formation. Complexes 5a,b were used as catalysts in hydrogen-transfer hydrogenation (TON up to 200). Reaction of MeLi with 3 followed by complexation with [PdCl2(η3-C 3H5)]2 yielded two diastereomers 7a,b, which were used as catalysts in the Suzuki-Miyaura cross-coupling reaction of aryl bromides with pinacolborane to yield the corresponding arylboronic esters (TON up to 799000). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Dochnahl, Maximilian,Doux, Marjolaine,Faillard, Emilie,Ricard, Louis,Le Floch, Pascal
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p. 125 - 134
(2007/10/03)
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- Simple deprotection of acetal type protecting groups under neutral conditions
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Heating acetals with ethylene glycol causes the deprotection of acetal type protecting groups. When acetals such as MOM ethers, MEM ethers, and THP ethers were heated in ethylene glycol or propylene glycol, solvolysis proceeded smoothly to produce alcohols in excellent yield. This reaction is a very promising method for chemoselective deprotection of acetal type protecting groups.
- Miyake, Hideyoshi,Tsumura, Takatsugu,Sasaki, Mitsuru
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p. 7213 - 7215
(2007/10/03)
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- Zirconium borohydride piperazine complex, an efficient, air and thermally stable reducing agent
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A zirconium borohydride piperazine complex (Ppyz)Zr(BH4) 2Cl2, obtained by the reaction of an ethereal solution of ZrCl4 and LiBH4 with piperazine is a stable, selective and efficient reducing agent. (Ppyz)Zr(BH4)2Cl 2 reduces aldehydes, ketones, silylethers, α, β-unsaturated carbonyl compounds and esters. The reactions were performed in diethyl ether at room temperature or under reflux, and the yields of the corresponding alcohols were excellent. The selective reduction of aldehydes in the presence of ketones and complete regioselectivity in the reduction of α,β-unsaturated carbonyl groups were observed.
- Tajbakhsh,Lakouraj,Shirini,Habibzadeh,Nikdoost
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p. 3295 - 3299
(2007/10/03)
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- Reduction of carbonyl compounds by lanthanide metal/2-propanol: In-situ generation of samarium isopropyloxide for stereoselective Meerwein-Ponndorf- Verley reduction
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The reduction of ketones and aldehydes with lanthanide metals (La, Ce, Sm, Yb) and a catalytic amount of iodine (5 mol %) in iPrOH proceeded smoothly to produce the corresponding alcohols as the major products in good yield, while in THF, methanol, and ethanol the pinacols were mainly produced. The yields of alcohols were improved most effectively by the use of Sm metal, the amount of pinacol produced thus being minimized. The actual reducing agent may be samarium isopropyloxide, which mediates the Meerwein-Ponndorf-Verley-type hydride-transfer reaction, since the reaction can be carried out catalytically with respect to samarium. The stereoselectivities of the reductions of the 2- and 4-substituted cyclohexanones with Sm/iPrOH were higher than those achieved with SmI2/iPrOH or Sm/ H20. The asymmetric reduction of acetophenone could be achieved to give the 1-phenylethanol in up to 95% ee in the presence of the chiral ligand 7. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Fukuzawa, Shin-Ichi,Nakano, Narihito,Saitoh, Takahide
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p. 2863 - 2867
(2007/10/03)
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- Quaternized amino functionalized cross-linked polyacrylamide as a new solid - Liquid phase transfer catalyst in reduction of carbonyl compounds with NaBH4
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Poly[N-(2-aminoethyl)acrylamido]trimethyl ammonium chloride resin was developed as a new polymeric phase transfer catalyst. This quaternized polyacrylamide catalyzed the chemoselective reduction of aldehydes and ketones by NaBH4 to give corresponding alcohols in high yields under mild conditions.
- Tamami, Bahman,Mahdavi, Hossein
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p. 821 - 826
(2007/10/03)
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- Dichlorobis[1,4-diazabicyclo(2,2,2)octane]-(tetrahydroborato)zirconium, [Zr(BH4)2Cl2(dabco)2] (ZrBDC), a new stable, efficient, and selective reducing agent
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High yield preparation of a new stable zirconium borohydride, [Zr(BH4)2Cl2(dabco)2] is described and its application for the selective and efficient reduction of aldehydes and ketones is presented.
- Firouzabadi,Iranpoor,Alinezhad
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p. 3575 - 3586
(2007/10/03)
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- Reduction of carbonyl compounds to the corresponding alcohols with isopropanol on dehydrated alumina under microwave irradiation
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The reduction of different types of aldehydes and ketones were performed in the presence of isopropylalcohol (as solvent and hydride source) under microwave irradiation. It is proved that dehydrated Woelm chromatographic alumina supported KOH catalyses these transformations. Regioselectivity was observed in the reduction of cinnamaldehyde and chemoselectivity was observed in the reduction of carbonyl in the presence of nitro group.
- Kazemi,Kiasat
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p. 2255 - 2260
(2007/10/03)
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- Chiral vinyl dioxazaborocines in synthesis: Asymmetric cuprate additions to β-boronyl acrylates and vinyl sulfones
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The first examples of the addition of organometallic reagents to electron deficient boron-substituted olefins are reported. Thus, copper catalysed addition of Grignard reagents to chiral acryloyl and vinysulfonyl dioxazaborocines, followed by oxidative re
- Farthing, Christopher N.,Marsden, Stephen P.
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p. 4235 - 4238
(2007/10/03)
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- 4-HYDROXY-BENZOPYRAN-2-ONES AND 4-HYDROXY-CYCLOALKYL[B]PYRAN-2-ONES USEFUL TO TREAT RETROVIRAL INFECTIONS
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The present invention relates to compounds of formula I which are 4-hydroxy-benzopyran-2-ones and 4-hydroxy-cycloalkyl[b]pyran-2-ones useful for inhibiting a retrovirus in a mammalian cell infected with said retrovirus. STR1 Wherein R 10 and R 20 taken together are: STR2
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- Poly-η-(pyrazine)zinc borohydride as a new stable, efficient and selective reducing agent
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Coordination polymer of unstable zinc borohydride and pyrazine is prepared and used as an stable, efficient and selective bench top reducing agent for a variety of organic compounds.
- Tamami,Lakouraj
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p. 3089 - 3096
(2007/10/03)
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- Zinc-promoted reactions. 6. The reduction of diphenylcyclopropenone in acidic media
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The reduction of diphenylcyclopropenone with zinc was investigated under a variety of conditions. The product distribution can be explained in terms of a general mechanism for zinc-promoted reductions.
- Di Vona, Maria Luisa,Rosnati, Vittorio
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p. 10925 - 10930
(2007/10/02)
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- A Selectivity Study of Activated Ketal Reduction with Borane Dimethyl Sulfide
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A chemo- and regioselectivity study of the reagent combination BH3*SMe2/TMSOTf for ketal reduction has been undertaken.It has revealed that simple 1,3-dioxanes reduce cleanly at low temperature in CH2Cl2 while simple 1,3-dioxolanes may give complete ring cleavage and dimerization products.A study of reduction of 4-substituted 1,3-dioxolanes has revealed a solvent-directed regioselectivity which in THF favors the secondary protected derivative.A mechanism is postulated to account for the selectivities based on recent thinking on acetal substitution reactions.
- Bartels, Birgit,Hunter, Roger
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p. 6756 - 6765
(2007/10/02)
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- DECARBOXYLATIVE PHOTOOXYGENATION OF CARBOXYLIC ACIDS BY THE USE OF ACRIDINE
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A new method of decarboxylative photooxygenation of free carboxylic acids is developed by the use of acridine as a light absorber, leading to alcohols after reductive treatment of the photolysate.
- Okada, Keiji,Okubo, Katsura,Oda, Masaji
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