- Tertiary arsine ligands for the Stille coupling reaction
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The Stille coupling reaction is one of the most important coupling reactions. It is well known that the triphenylarsine ligand can accelerate the reaction rate of Stille coupling. However, other arsine ligands have never been investigated for the Stille c
- Chishiro, Akane,Imoto, Hiroaki,Inaba, Ryoto,Konishi, Masafumi,Naka, Kensuke,Yumura, Takashi
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- Nickel-Catalyzed Reductive Cross-Coupling of Aryl Bromides with Vinyl Acetate in Dimethyl Isosorbide as a Sustainable Solvent
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A nickel-catalyzed reductive cross-coupling has been achieved using (hetero)aryl bromides and vinyl acetate as the coupling partners. This mild, applicable method provides a reliable access to a variety of vinyl arenes, heteroarenes, and benzoheterocycles, which should expand the chemical space of precursors to fine chemicals and polymers. Importantly, a sustainable solvent, dimethyl isosorbide, is used, making this protocol more attractive from the point of view of green chemistry.
- Huang, Xia,Jin, Jian,Lei, Chuanhu,Su, Mincong
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supporting information
(2022/01/15)
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- Methylenation for Aldehydes and Ketones Using 1-Methylbenzimidazol-2-yl Methyl Sulfone
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The methylenation reagent 1-methylbenzimidazol-2-yl methyl sulfone 2 reacts with various aldehydes and ketones in the presence of t-BuOK (room temperature, 1 h) in dimethylformamide to give the corresponding terminal alkenes generally in high yields. For sensitive substrates, the reaction is better carried out at low temperature using sodium hexamethyldisilazide in 1,2-dimethoxyethane. The byproduct is easily removed from the products, and the reaction conditions are mild and practical. Reagent 2 can be easily prepared from commercially available 2-mercaptobenzimidazole 5 in 95% yield without any expensive reagents.
- Ando, Kaori,Oguchi, Mai,Kobayashi, Takahisa,Asano, Haruka,Uchida, Nariaki
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p. 9936 - 9943
(2020/09/04)
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- Donor Rhodium Carbenes by Retro-Buchner Reaction
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Rhodium carbenes are key intermediates in a range of cycloadditions and insertion reactions. Herein, we report the first generation of donor RhII carbenes by decarbenation of 7-substituted 1,3,5-cycloheptatrienes. This discovery unlocks an improved retro-Buchner-cyclopropanation sequence, a Si?H insertion reaction for a broad-scope synthesis of allylsilanes, and a new method for the vinylogation of aldehydes. The last strategy led to the development of an iterative synthesis of E-polyenes, and to the total synthesis of navenones B and C.
- Mato, Mauro,Echavarren, Antonio M.
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supporting information
p. 2088 - 2092
(2019/01/25)
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- Cyclopropanation by Gold- or Zinc-Catalyzed Retro-Buchner Reaction at Room Temperature
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Through the design of a second generation of more reactive 7-substituted 1,3,5-cycloheptatrienes, a room-temperature gold(I)-catalyzed retro-Buchner-cyclopropanation sequence and the first zinc(II)-catalyzed version of this process, which uses inexpensive
- Mato, Mauro,Herlé, Bart,Echavarren, Antonio M.
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supporting information
p. 4341 - 4345
(2018/07/29)
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- Efficient and stereoselective nitration of mono- and disubstituted olefins with AgNO2 and TEMPO
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Nitroolefin is a common and versatile reagent. Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds. Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins. This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner.
- Maity, Soham,Manna, Srimanta,Rana, Sujoy,Naveen, Togati,Mallick, Arijit,Maiti, Debabrata
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supporting information
p. 3355 - 3358
(2013/04/10)
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- Stereoselective nitration of olefins with tBuONO and TEMPO: Direct access to nitroolefins under metal-free conditions
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Nitroolefins are essential elements for both synthetic chemistry and medicinal research. Despite significant improvements in nitration of olefin an efficient metal-free synthesis remains elusive so far. Herein, we disclose a new set of reagents to access nitroolefins in a single step under metal-free conditions. A wide range of olefins with diverse functionalities has been nitrated in synthetically useful yields. This transformation is operationally simple and exhibits excellent E-selectivity. Furthermore, site selective nitration in a complex setup makes this method advantageous.
- Maity, Soham,Naveen, Togati,Sharma, Upendra,Maiti, Debabrata
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supporting information
p. 3384 - 3387
(2013/07/26)
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- Studies of microwave-enhanced Suzuki-Miyaura vinylation of electron-rich sterically hindered substrates utilizing potassium vinyltrifluoroborate
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The Suzuki-Miyaura cross-coupling of sterically hindered and electron-rich ortho,ortho′-substituted aryl halides with potassium vinyltrifluoroborate utilizing microwave irradiation has been conducted while adjusting solvent ratio, irradiation time, and catalyst loading to find optimal conditions. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate leads to a mixture of the desired styrene derivative and the reduced product. 4-Bromo-1,3,5- trimethoxybenzene, methyl 4-bromo-3,5-dimethoxybenzoate, and mesitylene bromide were also coupled to test the breadth and scope of this methodology. Of these substrates tested only 4-bromo-1,3,5-trimethoxybenzene was not vinylated successfully, which is believed to be due to the electron-rich nature of this system.
- Brooker, Matthew D.,Cooper Jr., Stefan M.,Hodges, Dena R.,Carter, Rhiannon R.,Wyatt, Justin K.
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experimental part
p. 6748 - 6752
(2011/02/25)
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- General and highly active catalyst for mono and double Hiyama coupling reactions of unreactive aryl chlorides in water
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A new β-diketiminatophosphane Pd catalyst was found to be highly effective in the mono and double Hiyama coupling reactions of unactivated aryl chlorides in water.
- Lee, Dong-Hwan,Jung, Ji-Young,Jin, Myung-Jong
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supporting information; scheme or table
p. 9046 - 9048
(2011/02/17)
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- Low pressure vinylation of aryl and vinyl halides via Heck-Mizoroki reactions using ethylene
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Aryl bromides and iodides in the presence of catalytic amounts of a palladacycle derived from acetophenone oxime and 2 equiv of potassium acetate react with ethylene under ambient pressure (15-30 psi) to give the corresponding vinylarenes. The reactions work with both electron-deficient and electron-rich aryl compounds and tolerate wide variety of common functional groups. Vinyl bromides lead to 1,3-dienes in moderate yields.
- Smith, Craig R.,RajanBabu
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supporting information; experimental part
p. 1102 - 1110
(2010/03/25)
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- SLOW RELEASE OF ORGANOBORONIC ACIDS IN CROSS-COUPLING REACTIONS
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A method of performing a chemical reaction includes reacting a compound selected from the group consisting of an organohalide and an organo-pseudohalide, and a protected organoboronic acid represented by formula (I) in a reaction mixture: R1-B-T; where R1 represents an organic group, T represents a conformationalIy rigid protecting group, and B represents boron having sp3 hybridization. When unprotected, the corresponding organoboronic acid is unstable by the boronic acid neat stability test. The reaction mixture further includes a base having a pKB of at least 1 and a pal ladium catalyst. The method further includes forming a cross-coupled product in the reaction mixture.
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Page/Page column 53, 59-60
(2010/04/27)
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- Vinylation of aromatic halides using inexpensive organosilicon reagents. Illustration of design of experiment protocols
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The preparation of styrenes by palladium-catalyzed cross-coupling of aromatic iodides and bromides with divinyltetramethyldisiloxane (DVDS) in the presence of inexpensive silanolate activators has been developed. To facilitate the discovery of optimal reaction conditions, Design of Experiment (DoE) protocols were used. By the guided selection of reagents, stoichiometries, temperatures, and solvents, the vinylation reaction was rapidly optimized with three stages consisting of ca. 175 experiments (of a possible 1440 combinations). A variety of aromatic iodides undergo cross-coupling at room temperature in the presence of potassium trimethylsilanoate using Pd(dba) 2 in DMF in good yields. Triphenylphosphine oxide is needed to extend catalyst lifetime. Application of these conditions to aryl bromides was accomplished by the development of two complementary protocols. First, the direct implementation of the successful reaction conditions using aryl iodides at elevated temperature in THF provided the corresponding styrenes in good to excellent yields. Alternatively, the use of potassium triethylsilanolate and a bulky "Buchwald-type" ligand allows for the vinylation reactions to occur at or just above room temperature. A wide range of bromides underwent coupling in good yields for each of the protocols described.
- Denmark, Scott E.,Butler, Christopher R.
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p. 3690 - 3704
(2008/10/09)
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- Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes
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(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
- Lebel, Helene,Davi, Michael,Diez-Gonzalez, Silvia,Nolan, Steven P.
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p. 144 - 149
(2007/10/03)
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- Initial investigation into the Suzuki-Miyaura vinylation of hindered aryl bromides utilizing potassium vinyltrifluoroborate
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An initial study of the Suzuki-Miyaura cross-coupling of potassium vinyltrifluoroborate (2) and hindered aryl bromides is presented. Coupling of benzyl 3,5-bis(benzyloxy)-4-bromobenzoate (1) leads to a mixture of the desired styrene derivative, and the reduced product.
- Carter, Rhiannon R.,Wyatt, Justin K.
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p. 6091 - 6094
(2007/10/03)
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- Suzuki-Miyaura cross-coupling reactions of potassium vinyltrifluoroborate with aryl and heteroaryl electrophiles
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We have previously reported that the palladium-catalyzed cross-coupling reaction of potassium vinyltrifluoroborate with aryl electrophiles proceeds with good yields. Herein, we describe recent progress in optimizing the reaction, as well as outlining the scope and limitations of the reaction. The cross-coupling reaction can generally be effected using 2 mol % of PdCl2 and 6 mol % of PPh3 as a catalyst system in THF/H2O with Cs 2CO3 as a base. Moderate to good yields are obtained in the presence of a variety of functional groups.
- Molander, Gary A.,Brown, Adam R.
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p. 9681 - 9686
(2007/10/03)
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- Synthesis and olefination of carbonyl compounds using solid-supported reagents
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The development and application of three new solid-supported reagents for use in the synthesis or olefination of carbonyl compounds are described. The reagents include the Weinreb amide, Mukaiyama's S-2-pyridyl thioate and a Peterson methylenation reagent. As solid-supports p-benzyl alcohol resin, Wang resin and Merrifield resin (1-2% crosslinked polystyrene) have been used. The Royal Society of Chemistry.
- Hansen, Anne-Lene L.,Murray, Anthony,Tanner, David
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p. 4497 - 4505
(2008/09/18)
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- Vinylation of aryl bromides using an inexpensive vinylpolysiloxane
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(Chemical Equation Presented) A mild and general method for the palladium-catalyzed vinylation of aryl bromides has been developed. The use of tetrabutylammonium fluoride (TBAF) as the activator and an inexpensive and nontoxic vinyl donor, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4V, 1), allows for a general and high-yielding preparation of substituted styrenes.
- Denmark, Scott E.,Butler, Christopher R.
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- Suzuki cross-coupling reactions between alkenylboronic acids and aryl bromides catalysed by a tetraphosphane-palladium catalyst
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A range of alkenylboronic acids undergo Suzuki cross-coupling with aryl bromides in good yields in the presence of [PdCl(C3H 5)]2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl) methyl]cyclopentane as a catalyst. A wide variety of 1-arylprop-1-enes, 2-arylprop-1-enes, 2-arylbut-1-enes and 1,1-diarylethylene or styrene derivatives have been prepared. Moreover, the reaction tolerates several functions, such as acetyl, formyl, nitrile or nitro. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Peyroux, Eugenie,Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 1075 - 1082
(2007/10/03)
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- Simple and efficient protocol for the synthesis of functionalized styrenes from 1,2-dibromoethane and arylboronic acids
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(Matrix presented) A simple and efficient protocol for the preparation of functionalized styrenes is disclosed that employs the palladium-catalyzed cross-coupling reaction of arylboronic acids with vinyl bromide, generated in situ from 1,2-dibromoethane. The reaction is carried out under mild reaction conditions. Compared with the cross-coupling reactions usually employed to obtain vinylarenes, this protocol is very simple, overcomes the inconvenience of using of ethylene under pressure, and uses air-stable and widely available arylboronic acids instead of vinyl organometallic reagents.
- Lando, Vanusa R.,Monteiro, Adriano L.
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p. 2891 - 2894
(2007/10/03)
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- Preparation of preparing substituted indanones
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a process for the preparation of indanones of the formula II from, indanones of the formula I or of indanones of the formula IIa from indanones of the formula Ia comprises reacting an indanone of the formula I or Ia with a coupling component.
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- Palladium/imidazolium salt catalyzed coupling of aryl halides with hypervalent organostannates
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(equation presented) A Pd(OAc)2/imidazolium chloride system has been used to mediate the catalytic cross-coupling of aryl halides with organostannanes. The imidazolium salt IPr·HCl (IPr = 1,3-bis(2,6-diisopropylphenyl) imidazol-2-ylidene) in combination with TBAF (nBu4NF) was found to be most effective for the cross-coupling of aryl bromides and electron-deficient aryl chlorides with aryl and vinyl stannanes.
- Grasa, Gabriela A.,Nolan, Steven P.
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p. 119 - 120
(2007/10/03)
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- 1,3,5-Trineopentylbenzene and Related 1,3,5-Trialkylbenzenes Containing Groups with Both Steric and Conjugative Effects. 1H NMR Band Shape and 13C Spin Lattice Relaxation Time Measurements and Force Field Calculations
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2,4,6-Trialkylsubstituted styrenes, benzaldehydes and N-methylbenzaldimines were studied by the 1H NMR band shape and 13C spin lattice relaxation time techniques.The results were in most cases found to be well reproduced by molecular mechanics calculations with the Allinger MMP1 and MMP2 programs.In the case of 2,4,6-trineopentylstyrenes, it was found that a cis-β-vinylic methyl group is responsible for the high barrier to internal rotation (74 kJ mol-1) observed.The compound with a trans-β-vinylic methyl group has a barrier (-1), of similar magnitude to that of 2,4,6-trineopentylstyrene itself.For the benzaldehydes and N-methylbenzaldimines, an upper limit to the barrier of -1 in all cases was estimated by 13C spin lattice relaxation time measurements.A model involving free diffusion in a restricted range was used to calculate internal correlation times from T1 data.The influence of librational motions on rotational barriers from spin lattice relaxation time measurements is discussed.
- Anderson, Sven,Carter, Robert E.,Drakenberg, Torbjoern
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p. 579 - 596
(2007/10/02)
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- Structure of ω-Arylalkyl Radicals: A 13C CIDNP Investigation
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Thermolysis of a series of ω-arylalkanoyl m-chlorobenzoyl (and acetyl) peroxides at ca. 100 deg C in cyclohexanone and in hexachloroacetone was studied by using 13C chemically induced dynamic nuclear polarization.Analysis of the observed 13C polarizations indicate that all the three radicals (β-arylethyl, γ-arylpropyl and δ-arylbutyl) have open-chain structures with no evidence for aryl participation resulting in spirocycloalkylcyclohexadienyl radicals.
- Olah, George A.,Krishnamurthy, V. V.,Singh, Brij P.,Iyer, Pradeep S.
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p. 955 - 963
(2007/10/02)
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- Reductive Coupling of Aromatic Ketones by Low-valent Titanium Salts
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Reaction of sterically congested aromatic ketones with the McMurry reagent (4TiCl3, LiAlH4) in tetrahydrofuran yields is not only the olefins (E- and Z-isomers), but also the corresponding ethanes and some other products.We have studied the minor or non-normal products of this reaction.
- Bottino, Francesco,Finocchiaro, Paolo,Libertini, Emanuela,Reale, Antonino,Recca, Antonino
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