- Ultrasound in Organic Synthesis. 13. Some Fundamental Aspects of the Sonochemical Barbier Reaction
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The Barbier reaction of benzaldehyde, n-heptyl bromide, and lithium was effected under various sonochemical conditions.The rate of formation of 1-phenyloctanol depends strongly on the intensity of the ultrasonic waves and the temperature.For both parameters, an optimum is observed.An unusual variation of rate with temperature is evidenced, which reveals that the reaction is not mass-transport controlled.Electron microscopy examination of the metal shows the very important activation role of the acoustic waves, through the cavitation phenomenon.
- Souza-Barboza, Jayne C. de,Petrier, Christian,Luche, Jean-Louis
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- Electronically tuneable orthometalated RuII–NHC complexes as efficient catalysts for C–C and C–N bond formations via borrowing hydrogen strategy
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The catalytic activities of a series of simple and electronically tuneable cyclometalated RuII–NHC complexes (2a–d) were explored in various C–C/N bond formations following the borrowing hydrogen process. Slight modifications in the ligand backbone were noted to tune the activities of these complexes. Among them, the complex 2d featuring a 1,2,4-triazolylidene donor with a 4-NO2–phenyl substituent displayed the highest activity for the coupling of diverse secondary and primary alcohols with a low catalyst loading of 0.01 mol% and a sub-stoichiometric amount of inexpensive KOH base. The efficacy of this simple system was further showcased in the challenging one-pot unsymmetrical double alkylation of secondary alcohols using different primary alcohols. Moreover, the complex 2d also effectively catalyses the selective mono-N-methylation of various aromatic and aliphatic primary amines using methanol to deliver a range of N-methyl amines. Mechanistically, the β-alkylation reaction follows a borrowing hydrogen pathway which was established by the deuterium labelling experiment in combination with various control experiments. Intriguingly, in situ1H NMR and ESI-MS analyses evidently suggested the involvement of a Ru–H species in the catalytic cycle and further, the kinetic studies revealed a first order dependence of the reaction rate on the catalyst as well as the alcohol concentrations.
- Illam, Praseetha Mathoor,Rit, Arnab
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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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- Ir(NHC)-Catalyzed Synthesis of β-Alkylated Alcohols via Borrowing Hydrogen Strategy: Influence of Bimetallic Structure
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Multi N-heterocyclic carbene(NHC)-modified iridium catalysts were employed in the β-alkylation of alcohols; dimerization of primary alcohols (Guerbet reaction), cross-coupling of secondary and primary alcohols, and intramolecular cyclization of alcohols. Mechanistic studies of Guerbet reaction, including kinetic experiments, mass analysis, and density functional theory (DFT) calculation, were employed to explain the fast reaction promoted by bimetallic catalysts, and the dramatic reactivity increase of monometallic catalysts at the late stage of the reaction. (Figure presented.).
- Sung, Kihyuk,Lee, Mi-hyun,Cheong, Yeon-Joo,Kim, Yu Kwon,Yu, Sungju,Jang, Hye-Young
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supporting information
p. 3090 - 3097
(2021/05/10)
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- Selective C-alkylation Between Alcohols Catalyzed by N-Heterocyclic Carbene Molybdenum
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The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H2O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step.
- Liu, Jiahao,Li, Weikang,Li, Yinwu,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 3124 - 3128
(2021/09/20)
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- Switchable β-alkylation of secondary alcohols with primary alcohols by a well-defined cobalt catalyst
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β-alkylation of secondary alcohols with primary alcohols to selectively generate alcohols by a well-defined Co catalyst is presented. Remarkably, a low catalyst loading of 0.7 mol % can be employed for the reaction. More significantly, this study represents the first Co-catalyzed switchable alcohol/ketone synthesis by simply manipulating the reaction parameters. In addition, the transformation is environmentally friendly, with water as the only byproduct.
- Ding, Keying,Pandey, Bedraj,Xu, Shi
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supporting information
p. 1207 - 1212
(2021/05/29)
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- Gem-disilicon compound as well as preparation method and application thereof
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The invention relates to a novel gem-disilicon compound as well as a preparation method and application thereof. Different from a known gem-disilicon compound, the gem-disilicon compound provided by the invention has the advantage that two silicon groups of the gem-disilicon compound respectively contain two silicon-carbon bonds. Specifically, in the presence of a reducing agent, a disilylation reaction of terminal alkyne and monosubstituted silane is catalyzed through a 2, 9-diarylphenanthroline iron complex to generate a gem-disilicon compound containing two disubstituted silane structures.Silicon-hydrogen bonds in the gem-disilicon compound containing two disubstituted silane structures can be converted into silicon-oxygen bonds and silicon-fluorine bonds, and a corresponding silicon-based gem-disilicon compound containing two silicon-heteroatom bonds and two silicon-carbon bonds is generated. The gem-disilicon compound can react with water to generate polysiloxane or polyhedral oligomeric silsesquioxane with an adamantane structure, can also be used for synthesizing olefin and alcohol through functional group conversion of a silicon base, and has a very good application prospect.
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Paragraph 0177-0182
(2020/07/21)
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- Transition metal complexes of a bis(carbene) ligand featuring 1,2,4-triazolin-5-ylidene donors: structural diversity and catalytic applications
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Dialkylation of the 1,3-bis(1,2,4-triazol-1-yl)benzene with ethyl bromide results in the formation of [L-H2]Br2which, upon salt metathesis with NH4PF6, readily yields the bis(triazolium) salt [L-H2](PF6)2with non-coordinating counterions. [L-H2](PF6)2and Ag2O react in a 1?:?1 ratio to yield a binuclear AgI-tetracarbene complex of the composition [(L)2Ag2](PF6)2which undergoes a facile transmetalation reaction with [Cu(SMe2)Br] to deliver the corresponding CuI-NHC complex [(L)2Cu2](PF6)2. In contrast, the [L-H2]Br2reacts with [Ir(Cp*)Cl2]2to generate a doubly C-H activated IrIII-NHC complex5. Similarly, the triazolinylidene donor supported diorthometalated RuII-complex6is also obtained. Complexes5and6represent the first examples of a stable diorthometalated binuclear IrIII/RuII-complex supported by 1,2,4-triazolin-5-ylidene donors. The synthesized IrIII-NHC complex5is found to be more effective than its RuII-analogue (6) for the reduction of a range of alkenes/alkynesviathe transfer hydrogenation strategy. Conversely, RuII-complex6is identified as an efficient catalyst (0.01 mol% loading) for the β-alkylation of a wide range of secondary alcohols using primary alcohols as alkylating partnersviaa borrowing hydrogen strategy.
- Donthireddy, S. N. R.,Illam, Praseetha Mathoor,Rit, Arnab,Singh, Vivek Kumar
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p. 11958 - 11970
(2020/09/21)
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- Room-Temperature Guerbet Reaction with Unprecedented Catalytic Efficiency and Enantioselectivity
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We report herein an unprecedented highly efficient Guerbet-type reaction at room temperature (catalytic TON up to >6000). This β-alkylation of secondary methyl carbinols with primary alcohols has significant advantage of delivering higher-order secondary alcohols in an economical, redox-neutral fashion. In addition, the first enantioselective Guerbet reaction has also been achieved using a commercially available chiral ruthenium complex to deliver secondary alcohols with moderate yield and up to 92 % ee. In both reactions, the use of a traceless ketone promoter proved to be beneficial for the catalytic efficiency.
- Lau, Kai Kiat,Liao, Gang,Ng, Teng Wei,Pan, Hui-Jie,Zhao, Yu
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supporting information
p. 11384 - 11389
(2020/06/02)
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- Phosphine-free pincer-ruthenium catalyzed biofuel production: High rates, yields and turnovers of solventless alcohol alkylation
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Phosphine-free pincer-ruthenium carbonyl complexes based on bis(imino)pyridine and 2,6-bis(benzimidazole-2-yl) pyridine ligands have been synthesized. For the β-alkylation of 1-phenyl ethanol with benzyl alcohol at 140 °C under solvent-free conditions, (Cy2NNN)RuCl2(CO) (0.00025 mol%) in combination with NaOH (2.5 mol%) was highly efficient (ca. 93% yield, 372?000 TON at 12?000 TO h-1). These are the highest reported values hitherto for a ruthenium based catalyst. The β-alkylation of various alcohol combinations was accomplished with ease which culminated to give 380?000 TON at 19?000 TO h-1 for the β-alkylation of 1-phenyl ethanol with 3-methoxy benzyl alcohol. DFT studies were complementary to mechanistic studies and indicate the β-hydride elimination step involving the extrusion of acetophenone to be the overall RDS. While the hydrogenation step is favored for the formation of α-alkylated ketone, the alcoholysis step is preferred for the formation of β-alkylated alcohol. The studies were extended for the upgradation of ethanol to biofuels. Among the pincer-ruthenium complexes based on bis(imino)pyridine, (Cy2NNN)RuCl2(CO) provided high productivity (335 TON at 170 TO h-1). Sterically more open pincer-ruthenium complexes such as (Bim2NNN)RuCl2(CO) based on the 2,6-bis(benzimidazole-2-yl) pyridine ligand demonstrated better reactivity and gave not only good ethanol conversion (ca. 58%) but also high turnovers (ca. 2100) with a good rate (ca. 710 TO h-1). Kinetic studies indicate first order dependence on concentration of both the catalyst and ethanol. Phosphine-free catalytic systems operating with unprecedented activity at a very low base loading to couple lower alcohols to higher alcohols of fuel and pharmaceutical importance are the salient features of this report. This journal is
- Das, Babulal,Das, Kanu,Kumar, Akshai,Srivastava, Hemant Kumar,Yasmin, Eileen
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p. 8347 - 8358
(2020/12/31)
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- Iron-Catalyzed Dihydrosilylation of Alkynes: Efficient Access to Geminal Bis(silanes)
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Geminal bis(silanes) are versatile synthetic building blocks owing to their stability and propensity to undergo a variety of transformations. However, the scarcity of catalytic methods for their synthesis limits their structural diversity and thus their utility for further applications. Herein we report a new method for synthesis of geminal bis(silanes) by means of iron-catalyzed dihydrosilylation of alkynes. Iron catalysts were distinctly superior to the other tested catalysts, which clearly demonstrates that novel reactivity can be found by using iron catalysts. This method features 100% atom economy, regiospecificity, mild reaction conditions, and readily available starting materials. Using this method, we prepared a new type of geminal bis(silane) with secondary silane moieties, the Si-H bonds of which can easily undergo various transformations, facilitating the synthetic applications of these compounds. Preliminary mechanistic studies demonstrated that the reaction proceeds via two iron-catalyzed hydrosilylation reactions, the first generating β-(E)-vinylsilanes and the second producing geminal bis(silanes).
- Hu, Meng-Yang,Lian, Jie,Sun, Wei,Qiao, Tian-Zhang,Zhu, Shou-Fei
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p. 4579 - 4583
(2019/03/19)
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- Cooperative Mn(i)-complex catalyzed transfer hydrogenation of ketones and imines
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The synthesis and reactivity of Mn(i) complexes bearing bifunctional ligands comprising both the amine N-H and benzimidazole fragments are reported. Among the various ligands, the N-((1H-benzimidazol-2-yl)methyl)aniline ligand containing Mn(i) complex presented higher reactivity in the transfer hydrogenation (TH) of ketones in 2-propanol. Experimentally, it was established that both the benzimidazole and amine N-H proton played a vital role in the enhancement of the catalytic activity. Utilizing this system a wide range of aldehydes and ketones were reduced efficiently. Notably, the TH of several imines, as well as chemoselective reduction of unsaturated ketones, was achieved in the presence of this catalyst. DFT calculations were carried out to understand the plausible reaction mechanism which disclosed that the transfer hydrogenation reaction followed a concerted outer-sphere mechanism.
- Ganguli, Kasturi,Shee, Sujan,Panja, Dibyajyoti,Kundu, Sabuj
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p. 7358 - 7366
(2019/06/06)
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- C-Alkylation of Secondary Alcohols by Primary Alcohols through Manganese-Catalyzed Double Hydrogen Autotransfer
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A new Mn-catalyzed alkylation of secondary alcohols with non-activated alcohols is presented. The use of a stable and well-defined manganese pincer complex, stabilized by a PNN ligand, together with a catalytic amount of base enabled the conversion of renewable alcohol feedstocks to a broad range of higher-value alcohols in good yields with water as the sole byproduct. The strategy eliminates the need for exogenous and detrimental alkyl halides as well as the use of noble metal catalysts, making the C-alkylation through double hydrogen autotransfer a highly sustainable and environmentally benign process. Mechanistic investigations support a hydrogen autotransfer mechanism in which a non-innocent ligand plays a crucial role.
- El-Sepelgy, Osama,Matador, Esteban,Brzozowska, Aleksandra,Rueping, Magnus
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p. 3099 - 3102
(2018/09/27)
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- Manganese-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols under Phosphine-Free Conditions
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Manganese(I) complexes bearing a pyridyl-supported pyrazolyl-imidazolyl ligand efficiently catalyzed the direct β-alkylation of secondary alcohols with primary alcohols under phosphine-free conditions. The β-alkylated secondary alcohols were obtained in moderate to good yields with water formed as the byproduct through a borrowing hydrogen pathway. β-Alkylation of cholesterols was also effectively achieved. The present protocol provides a concise atom-economical method for C-C bond formation from primary and secondary alcohols.
- Liu, Tingting,Wang, Liandi,Wu, Kaikai,Yu, Zhengkun
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p. 7201 - 7207
(2018/07/21)
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- Tandem Cross Coupling Reaction of Alcohols for Sustainable Synthesis of β-Alkylated Secondary Alcohols and Flavan Derivatives
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A Ru(II) NHC complex (loading down to 0.001 mol%) catalyzed cross coupling of a broad range of aromatic, aliphatic and heterocyclic alcohols is reported. This protocol also functioned efficiently under solvent-free conditions. Remarkably, this catalytic system disclosed so far the highest TON of 288000 for the cross coupling of alcohols. Notably, this methodology was successfully applied for the one-pot synthesis of a range of flavan derivatives. A detailed DFT studies and kinetic experiments were performed to understand the reaction mechanism as well as the high reactivity of this catalytic system. (Figure presented.).
- Shee, Sujan,Paul, Bhaskar,Panja, Dibyajyoti,Roy, Bivas Chandra,Chakrabarti, Kaushik,Ganguli, Kasturi,Das, Ayan,Das, Gourab Kanti,Kundu, Sabuj
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supporting information
p. 3888 - 3893
(2017/10/07)
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- Oxygenation of Simple Olefins through Selective Allylic C?C Bond Cleavage: A Direct Approach to Cinnamyl Aldehydes
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A novel metal-free allylic C?C σ-bond cleavage of simple olefins to give valuable cinnamyl aldehydes is reported. 1,2-Aryl or alkyl migration through allylic C?C bond cleavage occurs in this transformation, which is assisted by an alkyl azide reagent. This method enables O-atom incorporation into simple unfunctionalized olefins to construct cinnamyl aldehydes. The reaction features simple hydrocarbon substrates, metal-free conditions, and high regio- and stereoselectivity.
- Liu, Jianzhong,Wen, Xiaojin,Qin, Chong,Li, Xinyao,Luo, Xiao,Sun, Ao,Zhu, Bencong,Song, Song,Jiao, Ning
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supporting information
p. 11940 - 11944
(2017/09/20)
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- Efficient and versatile catalysis for β-alkylation of secondary alcohols through hydrogen auto transfer process with newly designed ruthenium(II) complexes containing ON donor aldazine ligands
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A new series of ruthenium(II) carbonyl complexes, [RuCl(CO)(EPh3)2(L1-2)] (1–4) (E?=?P or As; H2L1?=?salicylaldazine, H2L2?=?2-hydroxynaphthaldazine), have been assembled from ruthenium(II) precursors [RuHCl(CO)(EPh3)3] and bidentate ON donor Schiff base ligands (H2L1-2). Both ligands and their new ruthenium(II) complexes have been characterized by elemental analyses, spectroscopic methods (UV, IR, NMR (1H, 13C, 31P) as well as ESI mass spectrometry. The molecular structures of H2L1 and 1 have been confirmed by single crystal X-ray diffraction. Based on the above studies, an octahedral coordination geometry around the metal center has been proposed for 1–4. To investigate the catalytic effectiveness of 1–4, the complexes have been used as catalysts in β-alkylation of secondary alcohols with primary alcohols and synthesis of quinolines. The effect of solvent, time, base, catalyst loading, and substituent of the ligand moiety on the reaction was studied. Notably, 1 was a more efficient catalyst toward alkylation of a wide range of alcohols and quinolines synthesis. The reusability of the catalyst was checked and the results showed up to six catalytic runs without significant loss of activity.
- Premkumar, Periyasamy,Manikandan, Rajendran,Nirmala, Muthukumaran,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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p. 3065 - 3079
(2017/10/11)
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- Cobalt-Catalyzed Alkylation of Secondary Alcohols with Primary Alcohols via Borrowing Hydrogen/Hydrogen Autotransfer
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Alcohols are promising sustainable starting materials because they can be obtained from abundant and indigestible biomass. The substitution of expensive noble metals in catalysis by earth abundant 3d metals, such as Mn, Fe, or Co, (nonprecious or base metals) is a related key concept with respect to sustainability. Here, we report on the first cobalt-catalyzed alkylation of secondary alcohols with primary alcohols. Easy-to-synthesize and easy-to-activate PN5P-pincer-ligand-stabilized Co complexes developed in our laboratory mediate the reaction most efficiently. The catalysis is applicable to a broad substrate scope and proceeds under relatively mild conditions. We have even demonstrated the coupling of a variety of purely aliphatic alcohols with a base or nonprecious metal catalyst. Mechanistic studies indicate that the reaction follows the borrowing hydrogen or hydrogen autotransfer concept.
- Freitag, Frederik,Irrgang, Torsten,Kempe, Rhett
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supporting information
p. 12110 - 12113
(2017/09/14)
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- Bifunctional Ru(II) complex catalysed carbon-carbon bond formation: an eco-friendly hydrogen borrowing strategy
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The atom economical borrowing hydrogen methodology enables the use of alcohols as alkylating agents for selective C-C bond formation. A bifunctional 2-(2-pyridyl-2-ol)-1,10-phenanthroline (phenpy-OH) based Ru(ii) complex (2) was found to be a highly efficient catalyst for the one-pot β-alkylation of secondary alcohols with primary alcohols and double alkylation of cyclopentanol with different primary alcohols. Exploiting the metal-ligand cooperativity in complex 2, several aromatic, aliphatic and heteroatom substituted alcohols were selectively cross-coupled in high yields using significantly low catalyst loading (0.1 mol%). An outer-sphere mechanism is proposed for this system as exogenous PPh3 has no significant effect on the rate of the reaction. Notably, this is a rare one-pot strategy for β-alkylation of secondary alcohols using a bifunctional Ru(ii)-complex. Moreover, this atom-economical methodology displayed the highest cumulative turn over frequency (TOF) among all the reported transition metal complexes in cross coupling of alcohols.
- Chakrabarti, Kaushik,Paul, Bhaskar,Maji, Milan,Roy, Bivas Chandra,Shee, Sujan,Kundu, Sabuj
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p. 10988 - 10997
(2016/12/06)
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- Synthesis and catalytic applications of ruthenium(ii)-phosphino-oxime complexes
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In this work, the preparation of the first ruthenium complexes containing a phosphino-oxime ligand is presented. Thus, the reaction of cis-[RuCl2(DMSO)4] (3) with 2.4 equivalents of 2-Ph2PC6H4CH=NOH (1) in refluxing THF led to the clean formation of the octahedral ruthenium(ii) derivative cis,cis,trans-[RuCl2{κ2-(P,N)-2-Ph2PC6H4CH=NOH}2] (5), whose structure was unambiguously confirmed by means of a single-crystal X-ray diffraction study. Complex 5 could also be synthesized from the reaction of the dimer [{RuCl(μ-Cl)(η6-p-cymene)}2] (4) with an excess of 1 in refluxing toluene. Treatment of 4 with 2 equivalents of 1, in CH2Cl2 at r.t., allowed also the preparation of the half-sandwich Ru(ii) derivative [RuCl{κ2-(P,N)-2-Ph2PC6H4CH=NOH}(η6-p-cymene)][PF6] (6). In addition, complexes 5 and 6 proved to be active catalysts for the rearrangement of aldoximes to primary amides, as well as for the α-alkylation/reduction of acetophenones with primary alcohols, with the former showing the best performances in both processes.
- Francos, Javier,Menéndez-Rodríguez, Lucía,Tomás-Mendivil, Eder,Crochet, Pascale,Cadierno, Victorio
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p. 39044 - 39052
(2016/06/01)
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- Alpha-phenyl alkyl alcohol polyoxyethylene ether phosphate and preparation method thereof
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The invention discloses an alpha-phenyl alkyl alcohol polyoxyethylene ether phosphate and a preparation method thereof, the alpha-phenyl alkyl alcohol polyoxyethylene ether phosphate is non-ion type, and has a molecular structure including a hydrophobic group and a hydrophilic group, the hydrophobic group is an alpha-phenyl alkyl chain segment, the hydrophilic group is a polyoxyethylene ether chain segment, and the molar ratio of hydrophobic group to hydrophilic group is 1:3-50. The non-APEO(alkyl phenol polyoxyethylene ether) emulsifier-alpha-phenyl alkyl alcohol polyoxyethylene ether phosphate has good wetting, penetration, emulsification, dispersion, solubilization and washing effects, can be used as an emulsifier, a detergent, a textile auxiliary, a dispersing agent, a softening agent, a crude oil demulsifier and the like, can completely substitute an alkyl phenol polyoxyethylene ether emulsifier, and can be widely used in detergents, personal care products, textile, papermaking, petroleum, farm chemicals, pharmaceuticals, printing, synthetic rubber, aqueous emulsion, coating, ink, glue, plastic and other industries.
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- Ruthenium(III)-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols
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A Ru(III)-NNN complex bearing a pyridyl-supported pyrazolyl-imidazolyl ligand was synthesized and utilized as the catalyst for the direct β-alkylation of secondary alcohols with primary alcohols. β-Alkylated secondary alcohols were obtained in moderate to high yields with water formed as the byproduct through a hydrogen borrowing pathway. The present protocol provides a concise atom-economical and environmentally benign method for C-C bond formation.
- Wang, Qingfu,Wu, Kaikai,Yu, Zhengkun
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p. 1251 - 1256
(2016/06/01)
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- Bifunctional RuII-Complex-Catalysed Tandem C?C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents
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Catalytic activities of a series of functional bipyridine-based RuIIcomplexes in β-alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional RuIIcomplex (3 a) bearing 6,6’-dihydroxy-2,2’-bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon?carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β-alkylated secondary alcohols this protocol is a rare one-pot strategy using a metal–ligand cooperative RuIIsystem. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction.
- Roy, Bivas Chandra,Chakrabarti, Kaushik,Shee, Sujan,Paul, Subhadeep,Kundu, Sabuj
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supporting information
p. 18147 - 18155
(2016/12/16)
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- Vinylation of Aldehydes Using Mn/Cr Alloy and a N4-Ligand/NiII-Catalyst
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We report an efficient and practical protocol for the Cr/Ni-catalyzed vinylation of aldehydes, based on the use of Mn/Cr alloy (ca. 10% Cr) and TMSCl. No additional Cr salts need to be added. In the presence of NiCl2 (0.3 mol%) and a bis(ketimino)-2,2′-bipyridine as N4-chelating ligand (1 mol%), the vinylations proceed smoothly at room temperature. The presence of catalytic amounts of MeOH and LiOAc as additives was found to further promote the efficiency of the catalytic system, even in the absence of the ligand. Detailed reaction monitoring revealed that LiOAc accelerates the product alcohol silylation, thus increasing the turnover rate.
- Harnying, Wacharee,Berkessel, Albrecht
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p. 6057 - 6061
(2015/04/14)
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- Catalytic asymmetric arylation of aliphatic aldehydes using a B/Zn exchange reaction
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Herein we describe the arylation of aliphatic aldehydes using the boron/zinc exchange reaction for the generation of transferable aryl groups, in the presence of chiral amino alcohol ligands. For the first time, a systematic investigation of this reaction
- Carlos, Andressa M.M.,Contreira, Maria Eduarda,Martins, Bruna S.,Immich, Maira F.,Moro, Angélica V.,Lüdtke, Diogo S.
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p. 1202 - 1203
(2015/02/19)
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- Catalyst-free dehydrative α-alkylation of ketones with alcohols: Green and selective autocatalyzed synthesis of alcohols and ketones
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Direct dehydrative α-alkylation reactions of ketones with alcohols are now realized under simple, practical, and green conditions without using external catalysts. These catalyst-free autocatalyzed alkylation methods can efficiently afford useful alkylated ketone or alcohol products in a one-pot manner and on a large scale by Ci£C bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes. Plain and simple: The title reaction has been realized under simple and practical conditions without using external catalysts, and can afford alkylated ketone or alcohol products in a one-pot manner and on a large scale. The reaction proceeds by Ci£C bond formation of the in situ generated intermediates with subsequent controllable and selective Meerwein-Pondorf-Verley-Oppenauer-type redox processes. Copyright
- Xu, Qing,Chen, Jianhui,Tian, Haiwen,Yuan, Xueqin,Li, Shuangyan,Zhou, Chongkuan,Liu, Jianping
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p. 225 - 229
(2014/01/17)
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- Tandem application of C-C bond-forming reactions with reductive ozonolysis
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Several variants of reductive ozonolysis, defined here as the in situ generation of aldehydes or ketones during ozonolytic cleavage of alkenes, are demonstrated to work effectively in tandem with a number of C-C bond-forming reactions. For reactions involving basic nucleophiles (1,2- addition of Grignard reagents, Wittig or Horner-Emmons olefinations, and directed aldol reactions of lithium enolates), the one-pot process offers a rapid and high-yielding alternative to traditional two-step protocols.
- Willand-Charnley, Rachel,Dussault, Patrick H.
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- Aldehyde-catalyzed transition metal-free dehydrative β-alkylation of methyl carbinols with alcohols
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Different to the borrowing hydrogen strategy in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the direct addition of aldehydes was found to be an effective but simpler way of alcohol activation that can lead to efficient and green aldehyde-catalyzed transition metal-free dehydrative C-alkylation of methyl carbinols with alcohols. Mechanistic studies revealed that the reaction proceeds via in situ formation of ketones by Oppenauer oxidation of the methyl carbinols by external aldehydes, aldol condensation, and Meerwein-Ponndorf-Verley (MPV)-type reduction of α,β-unsatutated ketones by substrate alcohols, affording the useful long chain alcohols and generating aldehydes and ketones as the by-products that will be recovered in the next condensation to finish the catalytic cycle. Copyright
- Xu, Qing,Chen, Jianhui,Liu, Quan
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supporting information
p. 697 - 704
(2013/04/10)
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- A new chiral sulfinyl-NH-pyridine ligand for Ir-catalyzed asymmetric transfer hydrogenation reaction
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A new flexible C1-symmetric tridentate ligand (S)-N-(2-(tert-butylsulfinyl)benzyl)-1-(pyridin-2-yl)methanamine sulfoxide (L1) was successfully prepared and utilized as a chiral ligand for Ir(I)-catalyzed ATH (asymmetric transfer hydrogenation) reactions. Without any cooperation of other chiral center, encouraging ee and conversion values have been achieved, which provide us a better understanding on these types of ligands and a new strategy to develop new high-efficiency chiral catalysts for asymmetric reaction.
- Tang, Lei,Wang, Qiwei,Wang, Juanjuan,Lin, Zechao,Wang, Xiaobei,Cun, Linfeng,Yuan, Weicheng,Zhu, Jin,Liao, Jian,Deng, Jingen
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scheme or table
p. 3839 - 3842
(2012/08/14)
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- PROCESS FOR PRODUCING OPTICALLY ACTIVE ALCOHOL
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Disclosed is a method for producing an optically active alcohol including reacting a titanium compound, an aromatic magnesium compound and a carbonyl compound in the presence of an optically active biphenol compound having a predetermined structure and an ether compound having a predetermined structure.
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Page/Page column 23
(2012/02/14)
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- Controlled alcohol-carbonyl interconversion by nickel catalysis
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All in one pot: A general synthetic platform allows the interconversion of alcohols and carbonyl compounds in a predictable and controlled fashion in one pot. Under the action of a Ni catalyst, PhCl, CsF, and arylboronates, several multistep alcohol-carbonyl interconversions have been achieved with good overall efficiency (see scheme). A one-pot nickel-catalyzed synthesis of flumecinol (a hepatic microsomal enzyme inducer) has also been demonstrated. Copyright
- Maekawa, Takehisa,Sekizawa, Hiromi,Itami, Kenichiro
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p. 7022 - 7026
(2011/09/30)
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- C-O hydrogenolysis catalyzed by Pd-PMHS nanoparticles in the company of chloroarenes
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Catalytic Pd(OAc)2 and polymethylhydrosiloxane (PMHS), in conjunction with aqueous KF, and a catalytic amount of an aromatic chloride, effects the chemo-, regio-, and stereoselective deoxygenation of benzylic oxygenated substrates at room temperature in THF. Preliminary mechanistic experiments suggest the process to involve palladium-nanoparticle-catalyzed hydrosilylation followed by C-O reduction. The chloroarene additive appears to facilitate the hydrogenolysis process through the slow controlled release of HCl.
- Rahaim, Ronald J.,Maleczka, Robert E.
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p. 584 - 587
(2011/04/23)
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- Selective arylation of aldehydes with di-rhodium(II)/NHC catalysts
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Here is described the preparation of four new rhodium(II) complexes bearing axial NHC ligands. The presence of electron-withdrawing bridging ligands resulted in an enhanced reactivity in the arylation of aldehydes with boronic acids when compared with the tetraacetate counterparts. Complex 15 (Rh 2tfa4(IPr)2) proved to be the most active catalyst for this transformation allowing the selective conversion of aromatic, aliphatic and vinyl aldehydes into the respective alcohols in excellent yields. It was demonstrated that the good group tolerance could be further extended to aromatic and conjugated ketones. DFT calculations carried out on this system showed the complementarily of the bridging ligands and axial ligand in these dinuclear complexes. It was also disclosed that Rh(II)/NHC catalytic system can promote the racemization of 1-phenyl ethanol.
- Trindade, Alexandre F.,André, Vania,Duarte, M. Teresa,Veiros, Luís F.,Gois, Pedro M.P.,Afonso, Carlos A.M.
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supporting information; experimental part
p. 8494 - 8502
(2010/11/18)
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- Zinc chloride enhanced arylations of secondary benzyl trifluoroacetates in the presence of b-hydrogen atoms
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Zinc or swim: Arylation of benzyl trifluoroacetates with arylzinc reagents in the presence of β- hydrogen atoms were realized under mild conditions. Both electron-rich and electron-deficient arene substrates were successfully arylated. This arylation method could offer a very versatile synthetic route to access a series of diversity-oriented diarylalkane motifs. TFA = trifluoroacetyl. Copyright
- Duan, Hui,Meng, Lingkui,Bao, Denghui,Zhang, Heng,Li, Yao,Lei, Aiwen
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supporting information; experimental part
p. 6387 - 6390
(2010/11/04)
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- A new approach to organomanganese compounds: The tellurium/manganese exchange reaction
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Diorganomanganese compounds react with aryl, vinyl, and alkynyl tellurides in a tellurium/manganese exchange reaction. The new mixed organomanganese reagents react selectively with electrophiles.
- Silva, Márcio S.,Comasseto, Jo?o V.,Dos Santos, Alcindo A.
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experimental part
p. 5426 - 5429
(2010/10/20)
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- Green alcohol couplings without transition metal catalysts: Base-mediated β-alkylation of alcohols in aerobic conditions
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Benzylic secondary alcohols can be alkylated in good yields at the β-position with primary alcohols promoted by KOH and NaOH, eliminating the need for toxic and expensive transition metal catalysts.
- Allen, Laura J.,Crabtree, Robert H.
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supporting information; experimental part
p. 1362 - 1364
(2010/09/16)
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- A concise synthesis of (S)-(+)-ginnol based on catalytic enantioselective addition of commercially unavailable Di(n -alkyl)zinc to aldehydes and ketones
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Catalytic, enantioselective n-alkyl addition of commercially unavailable di(n-alkyl)zinc reagents, which were prepared by a refined version of Charettes procedure with Grignard reagents, to aldehydes and ketones was developed. To minimize the side reactions in the catalysis by chiral phosphoramide ligand (1) or 3,3-diphosphoryl-BINOL ligand (2), a preparation of di(n-alkyl)zinc reagents with a 1:2.5:1.6 molar ratio of ZnClNaOMe/RMgCl under solvent-free conditions was essential. Optically pure (S)-(+)-ginnol (17) was readily synthesized in one step for the first time by the catalytic enantioselective n-nonylation of icosanal. Georg Thieme Verlag.
- Hatano, Manabu,Mizuno, Tomokazu,Ishihara, Kazuaki
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experimental part
p. 2024 - 2028
(2010/10/04)
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- Enantioselective arylation of aldehydes catalyzed by a soluble optically active polybinaphthols ligand
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A soluble chiral polymer ligand was synthesized by the polymerization of (R)-6,6′-dibutyl-3,3′-diformyl-2,2′-binaphthol (R-M-1) with 2,5-diaminopyridine (M-2) via a nucleophilic addition-elimination reaction. While arylboronic acids were used as the source of the transferable aryl group, the chiral polybinaphthols ligand in combination with Et2Zn without Ti(OiPr)4 exhibited higher enantioselectivity in asymmetric addition to aromatic aldehydes than alphatic aldehydes. When aromatic aldehydes with electron-withdrawing groups were chosen as substrates, the resulting diarylmethanols were produced in higher ee values than those with electron-donating groups as substrates. 2-Naphthaldehyde used as a substrate afforded product in 95% ee, which could be ascribed to the steric effect influence on this asymmetric arylation reaction. Moreover, the chiral polymer was easily recovered and reused, but exhibited a decrease of enantioselectivity in the third recycle.
- Huang, Xiaobo,Wu, Linglin,Xu, Jinqian,Zong, Lili,Hu, Hongwen,Cheng, Yixiang
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scheme or table
p. 6823 - 6826
(2009/04/07)
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- Emerging solvent-induced homochirality by the confinement of achiral molecules against a solid surface
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One hand mapping: By means of scanning tunneling microscopy, solvent-induced homochirality is shown to emerge in self-assembled monolayers of achiral molecules at the liquid-solid interface (see picture). The chirality of the solvent directs the macroscopic chirality of the monolayer. The dynamics of the monolayer structure as it evolves towards homochirality are probed by time-dependent measurements. (Figure Presented)
- Katsonis, Nathalie,Xu, Hong,Haak, Robert M.,Kudernac, Tibor,Tomovic, Zeljko,George, Subi,Van Der Auweraer, Mark,Schenning, Albert P. H. J.,Meijer,Feringa, Ben L.,De Feyter, Steven
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supporting information; experimental part
p. 4997 - 5001
(2009/03/11)
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- Axial coordination of NHC ligands on dirhodium(II) complexes: Generation of a new family of catalysts
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(Chemical Equation Presented) An efficient new methodology for the arylation of aldehydes is disclosed which uses dirhodium(II) catalysts and N-heterocyclic carbene (NHC) ligands. Complexes of Rh2(OAc) 4 with one and two NHCs attached on the axial positions were successfully isolated, fully characterized, and used as catalysts in the reaction. The saturated monocomplex ((NHC 5)Rh2(OAc)4) 31 was shown to be the most active catalyst and was particularly efficient in the arylation of alkyl aldehydes. DFT calculations support participation of complexes with one axial NHC in the reaction as the catalysts active species and indicate that hydrogen bonds involving dirhodium unit, reactants, and solvent (alcohol) play an important role on the reaction mechanism.
- Trindade, Alexandre F.,Gois, Pedro M. P.,Veiros, Luis F.,Andre, Vania,Duarte, M. Teresa,Afonso, Carlos A. M.,Caddick, Stephen,Cloke, F. Geoffrey N.
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p. 4076 - 4086
(2008/09/20)
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- Tuning the reactivity of dirhodium(II) complexes with axial N-heterocyclic carbene ligands: The arylation of aldehydes
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(Chemical Equation Presented) Efficient dinuclear catalysts: A complex of {Rh2(OAc)4} with two N-heterocyclic carbenes (NHCs) at the axial positions catalyzes the arylation of aldehydes (see picture; R = alkyl, aryl). DFT calculations reveal subtle stereoelectronic effects resulting from the NHC coordination to the dirhodium(II) complex and suggest that complexes with one axial NHC ligand are the catalytically active species.
- Gois, Pedro M. P.,Trindade, Alexandre F.,Veiros, Luis F.,Andre, Vania,Duarte, M. Teresa,Afonso, Carlos A. M.,Caddick, Stephen,Cloke, F. Geoffrey N.
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p. 5750 - 5753
(2008/09/16)
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- Synthesis of the bifunctional BINOL ligands and their applications in the asymmetric additions to carbonyl compounds
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Efficient one-step syntheses of the bifunctional BINOL and H8BINOL ligands (S)-6 and (S)-8 have been developed from the reaction of BINOL and H8BINOL with morpholinomethanol, respectively. The X-ray analyses of these compounds have revealed their structural similarity and difference. The bifunctional H8BINOL (S)-8 is found to be highly enantioselective for the reaction of diphenylzinc with many aliphatic and aromatic aldehydes and especially is the most enantioselective catalyst for linear aliphatic aldehydes. Unlike other catalysts developed for the diphenylzinc addition which often require the addition of a significant amount of diethylzinc with cooling (or heating) the reaction mixture in order to achieve high enantioselectivity, using (S)-8 needs no additive and gives excellent results at room temperature. (S)-8 in combination with diethylzinc and Ti(OiPr)4 can catalyze the highly enantioselective phenylacetylene addition to aromatic aldehydes. It can also promote the phenylacetylene addition to acetophenone at room temperature though the enantioselectivity is not very high yet. Without using Ti(OiPr)4 and a Lewis base additive, (S)-8 in combination with diethylzinc can catalyze the reaction of methyl propiolate with an aldehyde to form the highly functional γ-hydroxy-α,β-acetylenic esters except that the enantioselectivity is low at this stage. The bifunctional BINOL ligand (S)-6 in combination with Me2AlCl is found to be a highly enantioselective catalyst for the addition of TMSCN to both aromatic and aliphatic aldehydes.
- Qin, Ying-Chuan,Liu, Lan,Sabat, Michal,Pu, Lin
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p. 9335 - 9348
(2007/10/03)
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- Highly enantioselective addition of diphenylzinc to aliphatic and aromatic aldehydes catalyzed by a readily available H8-binol derivative
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(Chemical Equation Presented) All sorts of aldehydes 2 (R = aryl, vinyl, branched, and linear alkyl) undergo the highly enantioselective addition of diphenylzinc (1) in the presence of catalytic (S)-4 to give α-substituted benzyl alcohols 3 in high yields. In contrast to previous catalysts, no additive is required, the reaction is carried out at room temperature, and the reaction is equally effective with linear aldehydes.
- Qin, Ying-Chuan,Pu, Lin
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p. 273 - 277
(2007/10/03)
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- Direct preparation of benzylic manganese reagents from benzyl halides, sulfonates, and phosphates and their reactions: Applications in organic synthesis
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The use of highly active manganese (Mn)*, prepared by the Rieke method, was investigated for the direct preparation of benzylic manganese reagents. The oxidative addition of the highly active manganese to benzylic halides was easily completed under mild conditions. Moreover, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn* to the carbon-oxygen bonds of benzylic sulfonates and phosphates. The resulting benzylic manganese reagents were found to undergo cross-coupling reactions with a variety of electrophiles. Most of these reactions were carried out in the absence of any transition metal catalyst under mild conditions. In addition, the use of highly active manganese was also studied for preparation of homo-coupled products of functionalized benzyl halides without transition metal catalysts. These useful approaches provided not only a facile synthetic route to the preparation of resoricinolic lipids but a facile synthesis of functionalized 4-benzylpyridines by regioselective and chemo selective γ-addition of benzylic group to N-alkoxycarbonylpyridinum salts.
- Suh, YoungSung,Lee, Jun-Sik,Kim, Seoung-Hoi,Rieke, Reuben D.
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- Enantioselective alkylation of aldehydes with chiral organomagnesium amides (COMAs)
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(graph presented) Dialkylmagnesiums react with chiral secondary amines to form chiral organomagnesium amides (COMAs). These reagents alkylate aldehydes to form secondary alcohols with enantioselectivities up to 91:9 er.
- Yong, Kelvin H.,Taylor, Nicholas J.,Chong, J. Michael
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p. 3553 - 3556
(2007/10/03)
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- A new synthetic protocol for the direct preparation of organomanganese reagents; organomanganese tosylates and mesylates
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A new synthetic route to organomanganese sulfonate reagents has been developed. These useful reagents can be readily prepared via direct oxidative addition of highly reactive manganese to carbon-oxygen bonds of the corresponding tosylates and mesylates under mild conditions.
- Kim, Seung-Hoi,Rieke, Reuben D.
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p. 4931 - 4934
(2007/10/03)
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- Phosphine-directed stereo- and regioselective Ni-catalyzed reactions of Grignard reagents with allylic ethers
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Studies on the directed regio- and stereoselective Ni-catalyzed allylic substitution reactions involving methyl-and phenylmagnesium bromides and various acyclic and cyclic allylic ethers are reported. In the presence of a properly positioned internal Lewis base, C-C bonds can be formed catalytically and with excellent levels of selectivity. Internal chelation allows Ni-catalyzed C-C bond forming reactions that are otherwise non-selective, sluggish, or do not occur at all, to proceed to completion readily, in excellent yields, at ambient temperature and with high regio- and stereocontrol. Directed alkene isomerization highlights an especially attractive feature of the metal-catalyzed alkylation strategy: because the initial product contains a prostereogenic site that remains within reach of the internal Lewis base, it can be subjected to additional directed stereoselective manipulations.
- Didiuk, Mary T.,Morken, James P.,Hoveyda, Amir H.
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p. 1117 - 1130
(2007/10/03)
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- A facile one-pot synthesis of alkylarylcarbinols from α,α-dichloroarylmethanes and trialkylboranes in the presence of magnesium or lithium
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α-Chlorobenzylmagnesium chloride or α-chlorobenzyllithium generated from α,α-dichloroarylmethane and magnesium or lithium, reacts in situ with trialkylboranes in THF at room temperature to produce the corresponding alkylarylcarbinols in good yields after oxidation with sodium perborate.
- Li, Nan-Sheng,Yu, Su,Kabalka, George W.
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p. 101 - 105
(2007/10/03)
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