- Highly stereoselective allylation of aldehydes with pentacoordinate allylsilicates in hydroxylic media. Discrimination between linear and α-branched alkanals1
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Allylation of aldehydes with allyltrifluorosilanes in the presence of a wide variety of hydroxy compounds and triethylamine gave the corresponding homoallyl alcohols in regio- and stereospecific manner. Pentacoordinate allylsilicates are suggested as inte
- Kira,Sato,Sakurai
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- Carbonyl allylation in the absence of preformed allyl metal reagents: Reverse prenylation via iridium-catalyzed hydrogenative coupling of dimethylallene
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Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a-12a delivers products of reverse prenylation 1b-12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio-8b. As revealed by 2H NMR analysis, deuterium incorporation is observed at the vinylic position (80% 2H). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents. Copyright
- Skucas, Eduardas,Bower, John F.,Krische, Michael J.
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- An improved and practical synthesis route to antiproliferative (±)-shikonin and its O-acyl derivatives
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Shikonin and its O-acyl derivatives are attracting increasing levels of attention among medicinal chemists due to their potencies as highly selective cytotoxic agents against cancer cells. However, providing a large number of shikonin-related samples by organic synthesis remains challenging. In the present study, we developed an improved and practical synthesis route to shikonin derivatives by olefin metathesis that has enabled the gram-scale preparation of a prenylated tetramethylnaphthazaline, a key intermediate in the synthesis of shikonin. In addition, a method for the selective cleavage of the acyl protecting groups at the phenolic positions of tri-O-acylated shikonins has been developed that provides concise routes to diverse O-acylshikonin derivatives.
- Ono, Mana,Abe, Shouki,Higai, Koji,Higashi, Shoko,Saito, Setsuo,Saito, Ryota
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p. 738 - 746
(2020/12/09)
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- Photoredox Ni-Catalyzed Branch-Selective Reductive Coupling of Aldehydes with 1,3-Dienes
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We report here a Ni-catalyzed reductive coupling of aldehydes with widely available 1,3-dienes under visible-light photoredox dual catalysis. The homoallyic alcohols are obtained in broad scope with complete branched regioselectivity. Hantzsch ester is used as the hydrogen radical source to oxidize low-valent nickel salt affording Ni-H species. Preliminary mechanistic studies indicate a successive single-electron transfer (SET) pathway and the generation of a key π-allylnickel intermediate via Ni-H insertion of 1,3-diene in this synergistic catalytic process.
- Chen, Jie,Gu, Zheng-Yang,Li, Wen-Duo,Li, Yan-Lin,Xia, Ji-Bao
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p. 1528 - 1534
(2020/02/04)
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- Catalytic Allylation of Aldehydes Using Unactivated Alkenes
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Simple feedstock organic molecules, especially alkenes, are attractive starting materials in organic synthesis because of their wide availability. Direct utilization of such bulk, inert organic molecules for practical and selective chemical reactions, however, remains limited. Herein, we developed a ternary hybrid catalyst system comprising a photoredox catalyst, a hydrogen-atom-transfer catalyst, and a chromium complex catalyst, enabling catalytic allylation of aldehydes with simple alkenes, including feedstock lower alkenes. The reaction proceeded under visible-light irradiation at room temperature and with high functional group tolerance. The reaction was extended to an asymmetric variant by employing a chiral chromium complex catalyst.
- Tanabe, Shun,Mitsunuma, Harunobu,Kanai, Motomu
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supporting information
p. 12374 - 12381
(2020/07/14)
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- Indium(I)/CuFe2O4 Reagent for Allylation of Carbonyls and Epoxide Rearranged Carbonyls
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Abstract: Indium(I)/CuFe2O4 reagent forcarbonyl allylation and epoxide rearranged carbonyl allylation is proposed forformation of homoallylic alcohols. The In(I) reagent in combination withcatalytic amount of CuFe2O4support in situ formation of nucleophilicallylic indium from allyl halide in THF medium. Nucleophilic allylic indiumspecies react with carbonyls to form homoallyl alcohols in good to excellentyields. Under the presented reaction conditions arylepoxides undergo smoothrearrangement into aldehydes that are also allylated with formation of homoallylalcohols. The process is highly efficient and tolerates different functionalgroups.
- Kundu, M.,Mandal, S. P.,Mondal, B.,Roy, U. K.
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p. 2189 - 2196
(2020/12/25)
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- Method for synthesizing polysubstituted alpha, beta unsaturated ketones
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The invention particularly relates to a method for synthesizing polysubstituted alpha, beta unsaturated ketones. The method comprises the following steps: 1, adding Ni(cod), an N-heterocyclic carbene ligand, Cs2CO3 and a beta, gamma unsaturated ketone into a non-polar aprotic organic solvent, and mixing to obtain a mixture; 2, adding the mixture obtained in the step 1 into a dried container, reacting for 10-40 hours at the reaction temperature of 120-180 DEG C, and cooling to room temperature after the reaction is finished, so as to obtain a crude product; 3, purifying. According to the method, cheap Ni(cod) is adopted as a catalyst, carbon-carbon bonds are activated by a transition metal, power is provided for the reaction through isomerization of double bonds, the synthesis methodis simple, the substrates are stable and cheap, the reaction is less limited by the substrate, and the substrates are wide in application range.
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Paragraph 0049; 0056; 0057
(2020/03/06)
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- Silyl-Group-Directed Linear-Selective Allylation of Carbonyl Compounds with Trisubstituted Allylboronates Using a Copper(I) Catalyst
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A copper(I)-catalyzed linear-selective allylation of carbonyl compounds with trisubstituted allylboronates has been achieved by capitalizing on the electronic and steric effects of silyl groups. This reaction provides stereodefined trisubstituted homoallyl alcohol derivatives that bear a synthetically useful alkenyl silane moiety. The results of a computational study suggested that the silyl directing group thermodynamically stabilizes the sterically hindered allylcopper(I) intermediate and kinetically facilitates the carbonyl allylation path for the linear product by lowering the energy of its transition state.
- Hayashi, Yuta,Ito, Hajime,Iwamoto, Hiroaki,Ozawa, Yu
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p. 2471 - 2476
(2020/03/11)
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- Copper-Catalyzed Diamination of Alkenes of Unsaturated Ketohydrazones with Amines
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A convenient copper-catalyzed intra-/intermolecular diamination of β,γ-unsaturated hydrazones has been developed with simple amines as external amine sources. The protocol enables efficient access to various nitrogen-containing pyrazolines under mild reaction conditions.
- Chen, Manman,Wang, Li-Jing,Ren, Pei-Xing,Hou, Xiao-Ying,Fang, Zhang,Han, Meng-Nan,Li, Wei
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supporting information
p. 510 - 513
(2018/02/10)
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- Copper-Promoted 6- endo-trig Cyclization of β,γ-Unsaturated Hydrazones for the Synthesis of 1,6-Dihydropyridazines
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A novel and efficient strategy for the synthesis of 1,6-dihydropyridazines via copper-promoted 6-endo-trig cyclization of readily available β,γ-unsaturated hydrazones have been developed. A series of 1,6-dihydropyridazines have been synthesized by this method with good yields, high functional group tolerance, and remarkable regioselectivity under mild conditions. Importantly, the 1,6-dihydropyridazines can be efficiently converted to biologically important pyridazines in the presence of NaOH.
- Guo, Yong-Qiang,Zhao, Mi-Na,Ren, Zhi-Hui,Guan, Zheng-Hui
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supporting information
p. 3337 - 3340
(2018/06/11)
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- Palladium-Catalyzed Oxidative Borylation of Allylic C-H Bonds in Alkenes
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This communication describes an efficient palladium pincer complex-catalyzed allylic C-H borylation of alkenes. The transformation exhibits high regio- and stereoselectivity with a variety of linear alkenes. A synthetically useful feature of this allylic C-H borylation method is that all allyl-Bpin products can be isolated in usually high yields. Preliminary mechanistic studies indicate that this C-H borylation reaction proceeds via Pd(IV) pincer complex intermediates.
- Mao, Lujia,Bertermann, Rüdiger,Rachor, Simon G.,Szabó, Kálmán J.,Marder, Todd B.
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supporting information
p. 6590 - 6593
(2017/12/26)
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- Green Organocatalytic Dihydroxylation of Alkenes
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An inexpensive, green, metal-free one-pot procedure for the dihydroxylation of alkenes is described. H2O2 and 2,2,2-trifluoroacetophenone were employed as the oxidant and organocatalyst, respectively, in this highly sustainable protocol in which a variety of homoallylic alcohols, aminoalkenes, and simple alkenes were converted into the corresponding polyalcohols in good to excellent yields. This process takes advantage of an epoxidation reaction followed by an acidic treatment in which water participates in the ring opening of the in situ prepared epoxide to lead to the desired product.
- Theodorou, Alexis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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p. 1502 - 1509
(2017/04/01)
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- Iminoxyl Radical-Promoted Oxycyanation and Aminocyanation of Unactivated Alkenes: Synthesis of Cyano-Featured Isoxazolines and Cyclic Nitrones
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A novel and facile approach to vicinal oxycyanation and aminocyanation of internal unactivated alkenes is developed. This method utilizes the dichotomous reactivity of iminoxyl radical derived from the initiation of β,γ- and γ,δ-unsaturated ketoximes to provide the general difunctionalization of internal alkenes using tert-butyl hydroperoxide (TBHP) as the environmentally friendly oxidant, CuCN as the commercially available cyanating reagent, and pentamethyldiethylenetriamine (PMDETA) as the ligand. By using this protocol, a series of useful cyano-featured isoxazolines and cyclic nitrones were efficiently prepared.
- Chen, Fei,Zhu, Fei-Fei,Zhang, Man,Liu, Rui-Hua,Yu, Wei,Han, Bing
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supporting information
p. 3255 - 3258
(2017/06/23)
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- Mild bottom-up synthesis of indium(0) nanoparticles: Characterization and application in the allylation of carbonyl compounds
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Very reactive, monodisperse (4.0 ± 0.5 nm) spherical indium(0) nanoparticles have been generated in situ, in a simple, mild and efficient way, by fast reduction of commercially available indium(iii) chloride with lithium sand and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB) in THF, at room temperature, and in the absence of any anti-agglomeration additives or ligands. The as-synthesized bare InNPs were applied for the allylation of a variety of aldehydes and ketones. For most of the compounds tested, the corresponding homoallylic alcohols were obtained as the major product in good to excellent yield.
- Dorn, Viviana,Chopa, Alicia,Radivoy, Gabriel
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p. 23798 - 23803
(2016/03/12)
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- Nickel-catalyzed double bond transposition of alkenyl boronates for in situ syn-selective allylboration reactions
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The transposition of a homoallyl pinacol boronic ester was realized by a highly reactive nickel-catalyst system comprising NiCl2(dppp), zinc powder, ZnI2, and Ph2PH. The in situ generated Z-crotyl pinacol boronic esters were reacted with various aldehydes to form syn-homoallylic alcohols in high diastereoselectivities. The present nickel-catalyzed reaction is complementary to the iridium-catalyzed transposition reported by Murakami leading to the corresponding anti-homoallylic alcohols. Also, the multiple transposition of pentenyl pinacol boronic ester was realized.
- Weber, Felicia,Ballmann, Monika,Kohlmeyer, Corinna,Hilt, Gerhard
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supporting information
p. 548 - 551
(2016/02/18)
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- Oxime-mediated oxychlorination and oxybromination of unactivated olefins
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An oxime-mediated oxychlorination and oxybromination of unactivated olefins relying on palladium catalysis has been developed. A wide range of chlorinated and brominated isoxazolines has been synthesized in moderate to good yields. To demonstrate the value of the method, the brominated isoxazoline has been further converted to other useful synthetic feedstock.
- Dong, Kui-Yong,Qin, Hai-Tao,Liu, Feng,Zhu, Chen
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supporting information
p. 1419 - 1422
(2015/03/04)
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- Copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates: A facile synthesis of 2-arylpyrroles
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A novel and facile copper-catalyzed 5-endo-trig cyclization of ketoxime carboxylates for the synthesis of 2-arylpyrroles has been developed. The reaction tolerates a range of functional groups and is a practical procedure for rapid synthesis of 2-arylpyrroles in high yields under mild conditions. the Partner Organisations 2014.
- Du, Wei,Zhao, Mi-Na,Ren, Zhi-Hui,Wang, Yao-Yu,Guan, Zheng-Hui
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supporting information
p. 7437 - 7439
(2014/07/07)
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- Iminoxyl radical-promoted dichotomous cyclizations: Efficient oxyoximation and aminooximation of alkenes
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A novel iminoxyl radical-involved metal-free approach to vicinal oxyoximation and aminooximation of unactivated alkenes is developed. This method utilizes the dichotomous reactivity of the iminoxyl radical to furnish a general difunctionalization on alkenes using simple tert-butyl nitrite (TBN) as the iminoxyl radical initiator as well the carbon radical trap. By using this protocol, oxime featured 4,5-dihydroisoxazoles and cyclic nitrones were facilely prepared from β,γ- and γ,δ-unsaturated ketoximes, respectively.
- Peng, Xie-Xue,Deng, Yun-Jing,Yang, Xiu-Long,Zhang, Lin,Yu, Wei,Han, Bing
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supporting information
p. 4650 - 4653
(2015/01/08)
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- Radical-mediated diamination of alkenes with phenylhydrazine and azodicarboxylates: Highly diastereoselective synthesis of trans-diamines from cycloalkenes
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Metal-free synthesis: Diamination of alkenes by using phenylhydrazine and azodicarboxylates could be achieved in a one-pot manner under very mild conditions (see scheme; Boc=tert-butoxycarbonyl). This process works with the assistance of acetic acid by me
- Zhu, Ming-Kui,Chen, Yu-Chen,Loh, Teck-Peng
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supporting information
p. 5250 - 5254
(2013/05/23)
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- Cooperative titanocene and phosphine catalysis: Accelerated C-X activation for the generation of reactive organometallics
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The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C-X bonds at temperatures as low as -40 °C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.
- Fleury, Lauren M.,Kosal, Andrew D.,Masters, James T.,Ashfeld, Brandon L.
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p. 253 - 269
(2013/03/14)
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- Study on the coupling of acyclic esters with alkenes - The synthesis of 2-(2-hydroxyalkyl)cyclopropanols via cascade cyclization using allylsamarium bromide
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The radical cyclization between aliphatic acyclic esters and alkenes was achieved unprecedentedly in the presence of allylsamarium bromide with HMPA and H2O as additives. The cascade radical cyclization-ring-opening- anionic cyclization allowed facile and efficient access to 2-(2-hydroxyalkyl) cyclopropanols from readily available materials.
- Tu, Yawei,Zhou, Liejin,Yin, Ruifeng,Lv, Xin,Flowers Ii, Robert A.,Choquette, Kimberly A.,Liu, Huili,Niu, Qingsheng,Wang, Xiaoxia
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supporting information
p. 11026 - 11028
(2013/01/15)
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- Oxime radical promoted dioxygenation, oxyamination, and diamination of alkenes: Synthesis of isoxazolines and cyclic nitrones
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Up the tempo: The intramolecular addition of oxime radicals to C=C bonds was achieved by using DEAD and TEMPO to give 4,5-dihydroisoxazoles as a result of a C=O bond-forming, 5-exo-trig cyclization. γ,δ-Unsaturated ketoximes also reacted to afford cyclic nitrones through C-N bond formation. The reactions offer a metal-free approach for the vicinal difunctionalization of unactivated alkenes. Copyright
- Han, Bing,Yang, Xiu-Long,Fang, Ran,Yu, Wei,Wang, Chao,Duan, Xiao-Yong,Liu, Shuai
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supporting information; experimental part
p. 8816 - 8820
(2012/10/18)
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- Ni- and pd-catalyzed synthesis of substituted and functionalized allylic boronates
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Two highly efficient and convenient methods for the synthesis of functionalized and substituted allylic boronates are described. In one procedure, readily available allylic acetates are converted to allylic boronates catalyzed by Ni/PCy3 or Ni/PPh3 complexes with high levels of stereoselectivity and in good yields. Alternatively, the borylation can be accomplished with commercially available Pd catalysts [e.g., Pd 2(dba)3, PdCl2, Pd/C], starting with easily accessed allylic halides.
- Zhang, Ping,Roundtree, Ian A.,Morken, James P.
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p. 1416 - 1419
(2012/06/01)
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- Product selectivity control induced by using liquid-liquid parallel laminar flow in a microreactor
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Product selectivity control based on a liquid-liquid parallel laminar flow has been successfully demonstrated by using a microreactor. Our electrochemical microreactor system enables regioselective cross-coupling reaction of aldehyde with allylic chloride via chemoselective cathodic reduction of substrate by the combined use of suitable flow mode and corresponding cathode material. The formation of liquid-liquid parallel laminar flow in the microreactor was supported by the estimation of benzaldehyde diffusion coefficient and computational fluid dynamics simulation. The diffusion coefficient for benzaldehyde in Bu4NClO4-HMPA medium was determined to be 1.32 × 10-7 cm2 s-1 by electrochemical measurements, and the flow simulation using this value revealed the formation of clear concentration gradient of benzaldehyde in the microreactor channel over a specific channel length. In addition, the necessity of the liquid-liquid parallel laminar flow was confirmed by flow mode experiments.
- Amemiya, Fumihiro,Matsumoto, Hideyuki,Fuse, Keishi,Kashiwagi, Tsuneo,Kuroda, Chiaki,Fuchigami, Toshio,Atobe, Mahito
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scheme or table
p. 4256 - 4265
(2011/07/29)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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p. 2081 - 2089
(2011/04/19)
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- Palladium-catalyzed allyl cross-coupling reactions with in situ generated organoindium reagents
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Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp2- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.
- Lee, Kooyeon,Kim, Hyunseok,Mo, Juntae,Lee, Phil Ho
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scheme or table
p. 2147 - 2157
(2011/10/31)
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- Chemoselective reaction system using a two inlet micro-flow reactor: Application to carbonyl allylation
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A new strategy for chemoselective reaction using a two inlet micro-flow reactor is described. In this system, the combined use of suitable flow mode and corresponding cathode material enables chemoselective cathodic reduction to control the product regios
- Amemiya, Fumihiro,Fuse, Keishi,Fuchigami, Toshio,Atobe, Mahito
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supporting information; experimental part
p. 2730 - 2732
(2010/09/04)
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- METHOD FOR FORMING ALLYLIC ALCOHOLS
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A method of performing a chemical reaction includes reacting an allyl donor and a substrate in a reaction mixture, and forming a homoallylic alcohol in the reaction mixture. The substrate may be an aldehyde or a hemiacetal. The reaction mixture includes a ruthenium catalyst, carbon monoxide at a level of at least 1 equivalent relative to the substrate, and water at a level of at least 1 equivalent relative to the substrate, and an amine at a level of from 0 to 0.5 equivalent relative to the substrate. The reaction mixture may also include a halide, and the equivalents of the amine may be similar to those of the halide. The reacting includes maintaining the reaction mixture at a temperature of at least 40°C. The method may be catalytic in metal, environmentally benign, amenable to large-scale applications, and applicable to a wide range of substrates.
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Page/Page column 49-50
(2010/04/06)
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- Rh-catalyzed reductive coupling reaction of aldehydes with conjugated dienes promoted by triethylborane
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Rh(I) catalyzes the reductive coupling reaction of a wide variety of aldehydes with conjugated dienes in the presence of a stoichiometric amount of triethylborane to provide homoallyl alcohols in a single operation.
- Kimura, Masanari,Nojiri, Daisuke,Fukushima, Masahiro,Oi, Shuichi,Sonoda, Yusuke,Inoue, Yoshio
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supporting information; experimental part
p. 3794 - 3797
(2009/12/05)
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- Ruthenium-catalyzed C-C bond forming transfer hydrogenation: Carbonyl allylation from the alcohol or aldehyde oxidation level employing acyclic 1,3-dienes as surrogates to preformed allyl metal reagents
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Under the conditions of ruthenium-catalyzed transfer hydrogenation, commercially available acyclic 1,3-dienes, butadiene, isoprene, and 2,3-dimethylbutadiene, couple to benzylic alcohols 1a-6a to furnish products of carbonyl crotylation 1b-6b, carbonyl isoprenylation 1c-6c, and carbonyl reverse 2-methyl prenylation 1d-6d. Under related transfer hydrogenation conditions employing isopropanol as terminal reductant, isoprene couples to aldehydes 7a-9a to furnish identical products of carbonyl isoprenylation 1c-3c. Thus, carbonyl allylation is achieved from the alcohol or the aldehyde oxidation level in the absence of preformed allyl metal reagents. Coupling to aliphatic alcohols (isoprene to 1-nonanol, 65% isolated yield) and allylic alcohols (isoprene to geraniol, 75% isolated yield) also is demonstrated. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH). Copyright
- Shibahara, Fumitoshi,Bower, John F.,Krische, Michael J.
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p. 6338 - 6339
(2008/12/22)
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- Gallium-mediated allyl transfer from bulky homoallyl alcohol to aldehydes or alkynes: Control of dynamic σ-allylgalliums based on retro-allylation reaction
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A new method for the preparation and control of dynamic σ-allylgalliums is disclosed. Upon treatment with a Grignard reagent and gallium trichloride, bulky homoallyl alcohols undergo gallium-mediated retro-allylation reaction to provide σ-allylgallium reagents. The σ-allylgallium reagents generated were applied to carbonyl allylation. The retro-allylation reaction generates (Z)- and (E)-σ-crotylgalliums stereospecifically, starting from erythro- and threo-homoallyl alcohols, respectively. The stereochemically defined crotylgallium reagents effected stereoselective allylation of aldehydes. Allylgallation reaction of alkynes with the allylgallium reagents prepared by retro-allylation is also described.
- Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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p. 505 - 513
(2008/02/06)
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- Catalytic C-C coupling via transfer hydrogenation: Reverse prenylation, crotylation, and allylation from the alcohol or aldehyde oxidation level
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We report byproduct-free carbonyl reverse prenylation, crotylation, and allylation from the alcohol oxidation state via alcohol-allene hydrogen autotransfer. Specifically, exposure of alcohols 1a-6a to 1,1-dimethylallene, methylallene, and allene in the presence of [Ir(cod)(BIPHEP)]BARF (5-7.5 mol %) delivers reverse prenylation products 1c-6c, crotylation products 1d-3d, and allylation product 1e. Similarly, under the conditions of transfer hydrogenation employing isopropanol as terminal reductant, aldehydes 1b-6b are converted to the very same adducts 1c-6c, 1d-3d, and 1e. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH). The ability to achieve carbonyl addition directly from the alcohol oxidation level circumvents the redox manipulations so often required to convert alcohols to aldehydes. Further, through hydrogen autotransfer, there resides the potential to develop myriad byproduct-free carbonyl additions wherein alcohols and π-unsaturated compounds are exploited as coupling partners. Copyright
- Bower, John F.,Skucas, Eduardas,Patman, Ryan L.,Krische, Michael J.
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p. 15134 - 15135
(2008/09/17)
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- Nickel-catalyzed indium(I)-mediated double addition of aldehydes to 1,3-dienes
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In the presence of InI, Ni(acac)2 and PPh3, several 1,3-dienes were reacted with two molecules of aldehyde to give the corresponding 1,4- and 1,6-diols. The regioselectivity of the 1,4-/1,6-diol was efficiently regulated by the addit
- Hirashita, Tsunehisa,Kambe, Shinya,Tsuji, Hiromitsu,Araki, Shuki
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p. 2595 - 2597
(2008/03/27)
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- Dibutyltin oxide catalyzed allyl-transfer reaction from tertiary homoallylic alcohols to aldehydes
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A catalytic allyl-transfer reaction from tertiary homoallylic alcohols to aldehydes was achieved using dibutyltin oxide as a catalyst in toluene under reflux conditions. Various secondary homoallylic alcohols were prepared in high yield (up to 99%). When β-alkylated tertiary homoallylic alcohols were used, branched products were exclusively obtained. Georg Thieme Verlag Stuttgart.
- Yanagisawa, Akira,Aoki, Takahiro,Arai, Takayoshi
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p. 2071 - 2074
(2008/02/05)
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- Generation of allylic indium by hydroindation of 1,3-dienes and one-pot reaction with carbonyl compounds
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A hydroindation of 1,3-dienes by dichloroindium hydride (HInCl2) generates allylic indiums that react with carbonyl or imine moieties in a one-pot treatment. The former reaction proceeds in a radical manner, and the latter is ionic allylation.
- Hayashi, Naoki,Honda, Hiroyuki,Yasuda, Makoto,Shibata, Ikuya,Baba, Akio
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p. 4553 - 4556
(2007/10/03)
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- Gallium-mediated allyl transfer from bulky homoallylic alcohol to aldehydes via retro-allylation: Stereoselective synthesis of both erythro- and threo-homoallylic alcohols
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(Chemical Equation Presented) Retro-allylation of bulky gallium homoallylic alkoxides occurs to generate (Z)- and (E)-crotylgallium reagents stereospecifically, starting from erythro- and threo-homoallylic alcohols, respectively. The (Z)- and (E)-crotylgallium reagents immediately reacted with aromatic aldehydes to afford the corresponding erythro and threo-homoallylic alcohols, respectively.
- Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
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p. 3577 - 3579
(2007/10/03)
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- Chiral phosphine oxide BINAPO as a catalyst for enantioselective allylation of aldehydes with allyltrichlorosilanes
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The effectiveness of chiral phosphine oxide BINAPO as a catalyst for the enantioselective addition of allyltrichlorosilanes to aldehydes was demonstrated, wherein the combination of diisopropylethylamine and tetrabutylammonium iodide as additives is cruci
- Nakajima, Makoto,Kotani, Shunsuke,Ishizuka, Tadao,Hashimoto, Shunichi
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p. 157 - 159
(2007/10/03)
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- Regioselective synthesis of substituted 1-indanols, 2,3-dihydrobenzofurans and 2,3-dihydroindoles by electrochemical radical cyclization using an arene mediator
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Electrochemical reduction of haloarenes carrying 2-(1-hydroxybut-3-enyl), 2-allyloxy or N-allyl-N-methylamino group in the presence of phenanthrene as a mediator generated the corresponding aryl radicals and gave the corresponding 5-exo cyclization produc
- Kurono, Nobuhito,Honda, Eiichi,Komatsu, Fumikazu,Orito, Kazuhiko,Tokuda, Masao
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p. 1791 - 1801
(2007/10/03)
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- Palladium-catalyzed allylation of carbonyl compounds with various allylic compounds using In-InCl3 in aqueous media
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Various allylic compounds can be effectively applied to palladium-catalyzed allylation of carbonyl compounds via the formation of π-allylpalladium(II) intermediates and their transmetalation with indium in the presence of indium trichloride in aqueous media.
- Jang, Taeg-Su,Keum, Gyochang,Kang, Soon Bang,Chung, Bong Young,Kim, Youseung
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p. 775 - 779
(2007/10/03)
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- A New, Simple, and Selective Palladium-Catalyzed Cleavage of Triethylsilyl Ethers
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(Equation Presented) A simple procedure for the cleavage of triethylsilyl (TES) ethers in the presence of 10 wt % Pd/C in methanol or 95% ethanol is reported. This method allows selective removal of alkyl TES ethers in the presence of aromatic TES ethers or tert-butyldimethylsilyl (TBS) protecting groups.
- Rotulo-Sims, Delphine,Prunet, Joelle
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p. 4701 - 4704
(2007/10/03)
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- Allylation of carbonyl compounds with allylic gallium reagents
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Allylic gallium reagents, prepared from gallium trichloride and the corresponding allylic Grignard reagents, allylated carbonyl compounds in good yields in an aqueous medium as well as in organic solvent.
- Tsuji, Takashi,Usugi, Shin-ichi,Yorimitsu, Hideki,Shinokubo, Hiroshi,Matsubara, Seijiro,Oshima, Koichiro
-
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- Indium(III) chloride/chlorotrimethylsilane as a highly active Lewis acid catalyst system for the Sakurai-Hosomi reaction
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The indium(III) chloride/chlorotrimethylsilane system acts as a catalyst for the Sakurai-Hosomi reaction between allylsilanes and aldehydes. When γ-substituted allylsilanes such as crotylsilane and prenylsilane are used a high regioselectivity for γ-addit
- Onishi, Yoshiyuki,Ito, Takeshi,Yasuda, Makoto,Baba, Akio
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p. 1578 - 1581
(2007/10/03)
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- In situ formation of allyl ketones via Hiyama-Nozaki reactions followed by a chromium-mediated Oppenauer oxidation
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In Hiyama-Nozaki reactions of allylchromium with aldehydes the expected products are homo-allylalcohols. However, oxidation products derived from these, predominantly allyl ketones, can be common side products. This can be explained by an Oppenauer-(Meerwein-Ponndorf-Verley)-type mechanism (OMPV-reaction). The amount of oxidation is strongly dependent on the substitution pattern of the reaction partners and the reaction conditions. An appropriate choice of these can lead to preferential formation of ketones instead of the alcohols. In addition to its synthetic usefulness, the oxidation-reduction equilibrium is of the utmost importance for the design of enantioselective Hiyama-Nozaki reactions because it is also a potential racemization pathway.
- Schrekker, Henri S.,De Bolster, Martin W. G.,Orru, Romano V. A.,Wessjohann, Ludger A.
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p. 1975 - 1981
(2007/10/03)
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- Acid-mediated, chromium-catalyzed allylation of aldehydes
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Allyl bromides are efficiently coupled with aryl and aliphatic aldehydes in the presence of manganese metal, collidine hydrochloride, bis(diisopropylphosphino)ethane and chromium dichloride. Homoallylic alcohols are isolated in good to excellent yields directly from the reaction mixture.
- Shaughnessy, Kevin H.,Huang, Rongcai
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p. 1923 - 1928
(2007/10/03)
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- A highly atom efficient, solvent promoted addition of tetraallylic, tetraallenic, and tetrapropargylic stannanes to carbonyl compounds
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Tetraallylic, tetraallenic, and tetrapropargylic stannanes (0.25 equiv) react with aldehydes in methanol to provide unsaturated alcohols in good to excellent yields (56-99%). These reactions proceed exclusively with allylic rearrangement for tetra(2-butenyl)tin 2b and tetra(1,2-butadienyl)-tin 16c and predominantly with allylic rearrangement for tetrapropadienyltin 16a and tetra(2-butynyl)tin 6e. Allylation reactions also proceeded smoothly with reactive ketones such as ethyl pyruvate (9a) and cyclohexanone (9b). The corresponding TFA-catalyzed reactions of dimethyl acetals 4d and 4e are regiospecific with allylic rearrangement.
- McCluskey,Muderawan,Muntari,Young
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p. 7811 - 7817
(2007/10/03)
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- Indium mediated allylation and propargylation reactions of dimethyl acetals and ketals
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Indium mediated allylation and propargylation reactions of acetals and ketals with various allyl or propargyl bromides in aqueous media successfully provided the corresponding homoallylic or homopropargylic (and allenylic) alcohol, respectively, in moderate to good yields. Highly chemoselective allylation is also described. The ketal and aryl acetal could be selectively allylated over the aliphatic one in 80-84% yields.
- Kwon, Jin Sun,Pae, Ae Nim,Choi, Kyung Il,Koh, Hun Yeong,Kim, Youseung,Cho, Yong Seo
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p. 1957 - 1959
(2007/10/03)
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- Highly regioselective and stereoselective allylation of aldehydes via palladium-catalyzed in situ hydrostannylation of allenes
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(Equation presented) Highly regio-and stereoselective allylalion of aldehydes by allenes proceeds smoothly in aqueous/organic media in the presence of PdCl2-(PPh3)2, HCl, and SnCl2. The reaction likely occurs via hydrostannylation of allenes and allylation of aldehydes by the in situ generated allyltrichlorotins to afford the final products.
- Chang, Hao-Ming,Cheng, Chien-Hong
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p. 3439 - 3442
(2007/10/03)
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- A convenient one-flask procedure for the direct conversion of alkenes to homoallylic alcohols
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Homoallylic alcohols have been prepared from alkenes by direct reaction of the ozonide with an allylic bromide in the presence of zinc.
- Schloss, Jeffrey D.,Paquette, Leo A.
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p. 2887 - 2892
(2007/10/03)
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