- Direct deoxygenation of active allylic alcohols via metal-free catalysis
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Direct metal-free deoxygenation of highly active allylic alcohols catalyzed by a Br?nsted acid was achieved, which avoids tedious reaction steps and eliminates metal contamination. By examining a series of Br?nsted acids, alcohols, reaction temperatures and so on, up to 94% yield was obtained with 10 mol% TsOH·H2O as the catalyst and 2 equiv. of p-methylbenzyl alcohol as the reductant at 80 °C for 2 h. The system was mainly suitable for aromatic allylic alcohols, and the yield was excellent as determined via gram-scale synthesis. The main product was double bond near the side of a more electron-rich aryl group when allylic alcohols featuring different substituents at the 1 and 3 positions were used as the substrates. Deuterium-labelled experiments clearly demonstrated that the hydrogen source was the methylene of p-methylbenzyl alcohol and other control experiments indicated the existence of two ether intermediates. Interestingly, in situ hydrogen transfer of allylic benzyl ether is a key process, but kinetic isotopic effect studies (kH/kD = 1.28) showed that the C-H bond cleavage was not the rate-determining step. A possible mechanism involving carbocations, ether intermediates and hydrogen transfer is proposed.
- Han, Feng,Ji, Na,Liu, Qiaowen,Miao, Chengxia,Zhang, Tong,Zhuang, Hongfeng
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p. 1680 - 1689
(2022/03/02)
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- A photocatalyst-free photo-induced denitroalkylation of β-nitrostyrenes with 4-alkyl substituted Hantzsch esters at room temperature
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A photocatalyst-free stereoselectively photo-induced strategy for the denitroalkylation of β-nitrostyrenes using 4-alkyl substituted Hantzsch esters as the alkyl source under xenon lamp irradiation is developed. The reaction proceeds at room temperature and affords the corresponding products in moderate to excellent yields. The oxidant di-t-butyl peroxide serves as an efficient radical initiator under irradiation of a Xenon lamp, initiating alkyl radicals from the 4-alkyl substituted Hantzsch esters.
- Duan, Chunying,Hao, Xinyu,Jin, Kun,Li, Yaming,Wang, Jiaao,Zhang, Rong,Zhang, Siyu
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- Influences of Phenyl Rings on NHC Ligands with Bicyclic Architectures
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In addition to phosphanes, olefins, amines, and amides, over the past two decades N-heterocyclic carbene (NHC) has emerged as a useful alternative ligand. Based on a number of derivatization studies on NHC ligands, imidazol-2-ylidene and imidazolin-2-ylidene became the standard heterocyclic form, and bulky substituents have commonly been introduced on the nitrogen(s) adjacent to carbenic carbons. Our group previously developed NHCs equipped with noncarbenic carbons with a bicyclic architecture that gives them unique steric properties that make them bulky but accessible. In this study, we synthesized a novel type of NHC ligand that possesses a bicyclo[2.2.1]heptane architecture, and we compared five derivatives using copper-catalyzed allylic arylations with aryl Grignard reagents. The regioselectivity of the substitution obviously indicates that a phenyl ring over an active site has a characteristic effect on the resultant copper catalysts when γ-substitution is the major pathway.
- Ando, Shin,Miyata, Ryota,Matsunaga, Hirofumi,Ishizuka, Tadao
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p. 128 - 139
(2019/01/04)
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- Dual nickel and Lewis acid catalysis for cross-electrophile coupling: The allylation of aryl halides with allylic alcohols
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Controlling the selectivity in cross-electrophile coupling reactions is a significant challenge, particularly when one electrophile is much more reactive. We report a general and practical strategy to address this problem in the reaction between reactive and unreactive electrophiles by a combination of nickel and Lewis acid catalysis. This strategy is used for the coupling of aryl halides with allylic alcohols to form linear allylarenes selectively. The reaction tolerates a wide range of functional groups (e.g. silanes, boronates, anilines, esters, alcohols, and various heterocycles) and works with various allylic alcohols. Complementary to most current routes for the C3 allylation of an unprotected indole, this method provides access to C2 and C4-C7 allylated indoles. Preliminary mechanistic experiments reveal that the reaction might start with an aryl nickel intermediate, which then reacts with Lewis acid activated allylic alcohols in the presence of Mn.
- Jia, Xue-Gong,Guo, Peng,Duan, Jicheng,Shu, Xing-Zhong
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p. 640 - 645
(2018/01/28)
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- Flow chemistry as a discovery tool to access sp2-sp3 cross-coupling reactions via diazo compounds
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The work takes advantage of an important feature of flow chemistry, whereby the generation of a transient species (or reactive intermediate) can be followed by a transfer step into another chemical environment, before the intermediate is reacted with a coupling partner. This concept is successfully applied to achieve a room temperature sp2-sp3 cross coupling of boronic acids with diazo compounds, these latter species being generated from hydrazones under flow conditions using MnO2 as the oxidant.
- Tran, Duc N.,Battilocchio, Claudio,Lou, Shing-Bong,Hawkins, Joel M.,Ley, Steven V.
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p. 1120 - 1125
(2015/03/04)
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- Copper-Catalysed Allylic Substitution Using 2,8,14,20-Tetrapentylresorcinarenyl-Substituted Imidazolium Salts
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Unsymmetrical imidazolium salts, each having one nitrogen atom (N1) substituted by a cavity-shaped TPR group (TPR = 2,8,14,20-tetrapentylresorcinaren-5-yl), were tested in situ as proligands for the copper-catalysed allylic arylation of cinnamyl bromide w
- Kalo?lu, Murat,?ahin, Neslihan,Sémeril, David,Brenner, Eric,Matt, Dominique,?zdemir, ?smail,Kaya, Cemal,Toupet, Lo?c
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p. 7310 - 7316
(2015/11/25)
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- Photochemical Heck benzylation of styrenes catalyzed by Na[FeCp(CO)2]
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Iron-catalyzed Heck coupling of benzyl chlorides and styrenes proceeds under photochemical conditions using the well-known anionic complex, [FeCp(CO)2]- (Fp-), as a catalyst. The reaction likely proceeds through the established SN2 mechanism for Fp- alkylation, followed by styrene migratory insertion and β-hydride elimination steps that are enabled by photochemical CO dissociation.
- Waldhart, Greyson W.,Mankad, Neal P.
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supporting information
p. 171 - 174
(2015/03/05)
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- Catalytic allylic arylation of cinnamyl carbonates over palladium nanoparticles supported on a thermoresponsive polymer in water
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Poly(NIPAM-co-4-VP) undergoes a phase transition at the low critical solution temperature with a change from the hydrophilic to the hydrophobic core in a hydrophilic solvent. Palladium nanoparticles supported on such a thermoresponsive polymer support were demonstrated to catalyze the Tsuji-Trost reaction for the arylation of various cinnamyl carbonates by arylboronic acids. Therefore, a protocol developed using mild reaction conditions demonstrates the recyclability of the catalyst in an eco-friendly solvent such as water.
- Lee, Yongwoo,Shabbir, Saira,Lee, Sinyoung,Ahn, Hyunsoek,Rhee, Hakjune
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p. 3579 - 3583
(2015/06/25)
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- A palladium NNC-pincer complex: An efficient catalyst for allylic arylation at parts per billion levels
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Allylic arylation of allylic acetates by sodium tetraarylborates in the presence of ppb to ppm (molar) loadings of a palladium NNC-pincer complex catalyst in methanol at 50°C gave the corresponding arylated products in excellent yields. Total turnover numbers of up to 500 000 000 and turnover frequencies of up to 11 250 000 h-1 were achieved.
- Hamasaka, Go,Sakurai, Fumie,Uozumi, Yasuhiro
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supporting information
p. 3886 - 3888
(2015/03/04)
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- FeCl3·6H2O-catalyzed selective reduction of allylic halides to alkenes with concomitant oxidation of benzylic alcohols to aldehydes
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Iron-catalyzed direct reduction of allylic halides with benzylic alcohol was achieved, providing a new, simple, and efficient method for conducting highly regioselective hydrodehalogenation. This method not only features a readily available reductant, an
- Zhang, Houcai,Liu, Ruiting,Zhou, Xigeng
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p. 282 - 288
(2014/03/21)
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- Palladium-catalyzed allylic arylation of allylic ethers with arylboronic acids using hydrazone ligands
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Unsymmetrical 1,3-diarylpropenes were synthesized in good to high yields by the palladium-catalyzed allylic arylation of allylic ethers, such as a cinnamyl phenyl ether, with a variety of arylboronic acids using a hydrazone 1a-Pd(OAc)2 system in DMAc/H2O. Using this catalyst, eugenol was also synthesized from allyl phenyl ether with (4-hydroxy-3- methoxyphenyl)boronic acid pinacol ester. A palladium-catalyzed allylic arylation of cinnamyl phenyl ether derivatives with a variety of arylboronic acids using 5 mol-% of a hydrazone 1a-Pd(OAc)2 system in DMAc/H 2O at 50 °C gave 1,3-diarylpropenes in good yields. We also succeeded with the synthesis of eugenol by a palladium-catalyzed allylic arylation. Copyright
- Mino, Takashi,Kogure, Taketo,Abe, Taichi,Koizumi, Tomoko,Fujita, Tsutomu,Sakamoto, Masami
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p. 1501 - 1505
(2013/05/09)
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- Copper-catalyzed decarboxylative C(sp2)-C(sp3) coupling reactions via radical mechanism
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We have successfully developed an example of copper-catalyzed decarboxylative C(sp2)-C(sp3) coupling reactions via C-H functionalization for the first time. It is noteworthy that our catalytic system is very stable, low-cost, palladium-free, ligand-free, and easily accessible.
- Yang, Hailong,Sun, Peng,Zhu, Yan,Yan, Hong,Lu, Linhua,Qu, Xiaoming,Li, Tingyi,Mao, Jincheng
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supporting information; experimental part
p. 7847 - 7849
(2012/09/05)
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- Synthesis of 1,3-diarylpropenes through palladium-catalyzed mizoroki-heck and allyl cross-coupling reactions using hydrazones as ligands
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The palladium-catalyzed synthesis of unsymmetrical 1,3-diarylpropenes from allyl esters through a Mizoroki-Heck-type reaction with aryl iodides followed by allyl cross-coupling with a variety of arylboronic acids was developed; the products are obtained in moderate to good yields by using a hydrazone-Pd(OAc) 2 system. The synthesis of unsymmetrical 1,3-diarylpropenes from allyl esters by a Mizoroki-Heck-type reaction followed by allyl cross-coupling with a variety of arylboronic acids was developed; the products were obtained in moderate to good yields by using a hydrazone-Pd(OAc)2 system. Copyright
- Mino, Takashi,Koizumi, Tomoko,Suzuki, Saori,Hirai, Kiminori,Kajiwara, Kenji,Sakamoto, Masami,Fujita, Tsutomu
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supporting information; experimental part
p. 678 - 680
(2012/03/10)
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- Self-assembled poly(imidazole-palladium): Highly active, reusable catalyst at parts per million to parts per billion levels
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Metalloenzymes are essential proteins with vital activity that promote high-efficiency enzymatic reactions. To ensure catalytic activity, stability, and reusability for safe, nontoxic, sustainable chemistry, and green organic synthesis, it is important to develop metalloenzyme-inspired polymer-supported metal catalysts. Here, we present a highly active, reusable, self-assembled catalyst of poly(imidazole-acrylamide) and palladium species inspired by metalloenzymes and apply our convolution methodology to the preparation of polymeric metal catalysts. Thus, a metalloenzyme-inspired polymeric imidazole Pd catalyst (MEPI-Pd) was readily prepared by the coordinative convolution of (NH4)2PdCl4 and poly[(N-vinylimidazole)-co-(N- isopropylacrylamide)5] in a methanol-water solution at 80 °C for 30 min. SEM observation revealed that MEPI-Pd has a globular-aggregated, self-assembled structure. TEM observation and XPS and EDX analyses indicated that PdCl2 and Pd(0) nanoparticles were uniformly dispersed in MEPI-Pd. MEPI-Pd was utilized for the allylic arylation/alkenylation/vinylation of allylic esters and carbonates with aryl/alkenylboronic acids, vinylboronic acid esters, and tetraaryl borates. Even 0.8-40 mol ppm Pd of MEPI-Pd efficiently promoted allylic arylation/alkenylation/vinylation in alcohol and/or water with a catalytic turnover number (TON) of 20 000-1 250 000. Furthermore, MEPI-Pd efficiently promoted the Suzuki-Miyaura reaction of a variety of inactivated aryl chlorides as well as aryl bromides and iodides in water with a TON of up to 3 570 000. MEPI-Pd was reused for the allylic arylation and Suzuki-Miyaura reaction of an aryl chloride without loss of catalytic activity.
- Yamada, Yoichi M. A.,Sarkar, Shaheen M.,Uozumi, Yasuhiro
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supporting information; experimental part
p. 3190 - 3198
(2012/04/10)
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- TPGS-750-M: A second-generation amphiphile for metal-catalyzed cross-couplings in water at room temperature
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An environmentally benign surfactant (TPGS-750-M), a diester composed of racemic α-tocopherol, MPEG-750, and succinic acid, has been designed and readily prepared as an effective nanomicelle-forming species for general use in metal-catalyzed cross-coupling reactions in water. Several "name" reactions, including Heck, Suzuki-Miyaura, Sonogashira, and Negishi-like couplings, have been studied using this technology, as have aminations, C-H activations, and olefin metathesis reactions. Physical data in the form of DLS and cryo-TEM measurements suggest that particle size and shape are key elements in achieving high levels of conversion and, hence, good isolated yields of products. This new amphiphile will soon be commercially available.
- Lipshutz, Bruce H.,Ghorai, Subir,Abela, Alexander R.,Moser, Ralph,Nishikata, Takashi,Duplais, Christophe,Krasovskiy, Arkady,Gaston, Ricky D.,Gadwood, Robert C.
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experimental part
p. 4379 - 4391
(2011/07/06)
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- A highly active and reusable self-assembled poly(imidazole/palladium) catalyst: Allylic arylation/alkenylation
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Gobs of globules: A polymeric imidazole/acrylamide palladium catalyst, MPPI-Pd (M=PdIICl and Pd0), was utilized for the allylic arylation/alkenylation of allylic esters with aryl/alkenylboronic acids and tetraaryl borates. Low catalyst loadings efficiently promoted the reaction with a catalytic turnover number of 20000-1250000. The catalyst can be reused without loss of catalytic activity.
- Sarkar, Shaheen M.,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information; experimental part
p. 9437 - 9441
(2011/11/06)
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- Surfactant-Enabled Transition Metal-Catalyzed Chemistry
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In one embodiment, the present application discloses mixtures comprising (a) water in an amount of at least 1% wt/wt of the mixture; (b) a transition metal catalyst; and (c) one or more solubilizing agents; and methods for using such mixtures for performing transition metal mediated bond formation reactions.
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- Practical iron-catalyzed allylations of aryl grignard reagents
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An operationally simple iron-catalyzed reductive cross-coupling reaction between aryl halides and allyl electrophiles has been developed. The underlying domino process exhibits high versatility with respect to the allylic leaving group (acetate, tosylate, diethyl phosphate, methyl carbonate, trimethylsilanolate, methanethiolate, chloride, bromide) and high economic and environmental sustainability with respect to the catalyst system (0.2-5 mol% tris(acetylacetonato)iron(III), ligand-free) and reaction conditions (tetrahydrofuran, 0°C, 45 min).
- Mayer, Matthias,Czaplik, Waldemar M.,Von Wangelin, Axel Jacobi
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supporting information; experimental part
p. 2147 - 2152
(2010/12/18)
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- An efficient 1,3-allylic carbonyl transposition of chalcones
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A very simple, convenient, and efficient procedure is reported for the 1,3-allylic carbonyl transposition of chalcones. The transposition can be achieved by reduction of chalcones to 1,3-diarylpropan-1-ols and dehydration of the latter to give 1,3-diarylpropenes followed by benzylic/allylic oxidation.
- Khurana, Jitender M.,Dawra, Kiran,Majumdar, Susruta
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experimental part
p. 69 - 72
(2010/03/24)
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- Allylic Ethers as educts for Suzuki-Miyaura couplings in water at room temperature
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(Chemical Equation Presented) The first examples of Suzuki-Miyaura couplings of allylic ethers are reported. These can be done not only under very mild room-temperature conditions but also in water as the only medium. The process is made possible by micel
- Nishikata, Takashi,Lipshutz, Bruce H.
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supporting information; experimental part
p. 12103 - 12105
(2009/12/31)
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- FeCl3 · 6H2O catalyzed disproportionation of allylic alcohols and selective allylic reduction of allylic alcohols and their derivatives with benzyl alcohol
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Iron chloride has been found to be an efficient catalyst for the disproportionation of allylic alcohols, which provides a convenient method for selective transformation of allylic alcohols to alkenes and α,β- unsaturated ketones. Furthermore, this catalytic system is also effective for highly selective allylic reduction of allylic alcohols, allylic ethers, and allylic acetates with benzyl alcohol under neutral and convenient reaction conditions.
- Wang, Jialiang,Huang, Wen,Zhang, Zhengxing,Xiang, Xu,Liu, Ruiting,Zhou, Xigeng
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supporting information; experimental part
p. 3299 - 3304
(2009/09/08)
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- Palladium(0)-catalyzed direct cross-coupling reaction of allylic alcohols with aryl- and alkenylboronic acids
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Allylic alcohols can be used directly for the palladium(0)-catalyzed allylation of aryl- and alkenylboronic acids with a wide variety of functional groups. A triphenylphosphine-ligated palladium catalyst turns out to be most effective for the cross-coupling reaction and its low loading (less than 1 mol%) leads to formation of the coupling product in high yield. The Lewis acidity of the organoboron reagents and poor leaving ability (high basicity) of the hydroxyl group are essential for the cross-coupling reaction. The reaction process is atom-economical and environmentally benign, because it needs neither preparation of allyl halides and esters nor addition of stoichiometric amounts of a base. Furthermore, allylic alcohols containing another unsaturated carbon-carbon bond undergo arylative cyclization reactions leading to cyclopentane formation. The Royal Society of Chemistry.
- Tsukamoto, Hirokazu,Uchiyama, Tomomi,Suzuki, Takamichi,Kondo, Yoshinori
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supporting information; experimental part
p. 3005 - 3013
(2009/02/03)
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- Palladium(0)-catalyzed direct cross-coupling reaction of allyl alcohols with aryl- and vinyl-boronic acids
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Allyl alcohols can be directly used for the palladium-catalyzed allylation of aryl- and vinyl-boronic acids without the aid of a base.
- Tsukamoto, Hirokazu,Sato, Masanori,Kondo, Yoshinori
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p. 1200 - 1201
(2007/10/03)
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- Rhodium-catalyzed cross-coupling of allyl alcohols with aryl- and vinylboronic acids in ionic liquids
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The direct coupling of aryl-and vinylboronic acids with allylic alcohols has been achieved in ionic liquids using a rhodium catalyst.
- Kabalka, George W.,Dong, Gang,Venkataiah, Bollu
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p. 893 - 895
(2007/10/03)
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- Palladium(0) complexes of a 15-membered macrocyclic triolefin as a recoverable catalyst - Monomer- and polystyrene-anchored versions
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Preparation of the 15-membered cycle (E,E,E)-1,6,11-tris[(2,4,6- triisopropylphenyl)sulfonyl]-1,6,11-triazacyclopentadeca-3,8,13-triene (8) is reported. This cyclic triolefin forms a stable Pd°complex 9 which catalyzes several cross-coupling reactions and
- Cortés, Jordi,Moreno-Ma?as, Marcial,Pleixats, Roser
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p. 239 - 243
(2007/10/03)
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- Preparation of 1,3-Diarylpropenes by Phosphine-Free Palladium(0)-Catalyzed Suzuki-Type Coupling of Allyl Bromides with Arylboronic Acids
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1,2-Diarylpropenes 3 featuring different substituents at the aryl rings are obtained in high yields by a modified Suzuki coupling between cinnamyl bromides and arylboronic acids using the phosphine-free Pd(dba)n (n = 1.5-2) as catalyst, in benzene and in
- Moreno-Manas, Marcial,Pajuelo, Francesca,Pleixats, Roser
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p. 2396 - 2397
(2007/10/02)
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