- Conversion of Alkyl Halides into Alcohols Using a Near Stoichiometric Amount of Molecular Oxygen: An Efficient Route to 18O- And 17O-Labeled Alcohols
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In the presence of near stoichiometric amount of molecular oxygen, various alkyl halides were converted to the corresponding alcohols in high yields through aerobic radical reaction promoted by a Bu2(t-Bu)SnCl/NaBH3CN catalytic system. Isotope-labeled alcohols were prepared with 18O2 and 17O2 without loss of the isotopic purities of the starting oxygen gases.
- Sawamura, Masaya,Kawaguchi, Yasuhide,Nakamura, Eiichi
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- New One-pot Cross-coupling Reaction between Grignard Reagents and Alkoxymethyldiphenylphosphonium Iodides in situ-Formed from Alcohols, Chlorodiphenylphosphine and Iodomethane
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A new one-pot cross-coupling reaction between Grignard reagents and alkoxymethyldiphenylphosphonium iodides, which were in situ-formed from nBuLi-treated alcohols, chlorodiphenylphosphine and iodomethane, proceeded smoothly to afford the corresponding coupling products in good to high yields.
- Shintou, Taichi,Kikuchi, Wataru,Mukaiyama, Teruaki
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- On the role of additives in alkyl-alkyl Negishi cross-couplings
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An additives study for the alkyl-alkyl Negishi reaction using an NHC-Pd catalyst revealed that bromide salts promote coupling while the cation is mechanistically benign. A double titration revealed that the cross-coupling begins at a 1 1 ratio of LiBr su
- Achonduh, George T.,Hadei, Niloufar,Valente, Cory,Avola, Stephanie,O'Brien, Christopher J.,Organ, Michael G.
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- Differentiating C-Br and C-Cl bond activation by using solvent polarity: Applications to orthogonal alkyl-alkyl negishi reactions
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A pot to share: A Calkyl-Cl bond can be rendered "dormant" or "active" in the Negishi alkyl-alkyl cross-coupling by a simple solvent polarity "switch" (see scheme). Adjustment from a 1:2 to a 2:1 solvent ratio of dimethylimidazolidinone: tetrahydrofuran enables orthogonal alkyl-alkyl Negishi cross-coupling strategies to be carried out on bifunctional bromochloroalkanes in one pot at room temperature.
- Hadei, Niloufar,Achonduh, George T.,Valente, Cory,O'Brien, Christopher J.,Organ, Michael G.
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- Copper-catalyzed cross-coupling of alkylsamarium reagents with alkyl halides
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SmI2/HMPA converts alkyl iodides and bromides to alkyl samarium reagents which can be cross-coupled with primary alkyl iodides and bromides and secondary iodides in the presence of Cu(I) halides or Li2CuCl4 at room temperature. The alkylation of primary iodides gives good yields of cross-coupling products with negligible home-coupling produces. The method is especially useful for the small scale cross-coupling reactions.
- Berkowitz, William F.,Wu, Yanzhong
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- A user-friendly, all-purpose Pd-NHC (NHC = N-heterocyclic carbene) precatalyst for the Negishi reaction: A step towards a universal cross-coupling catalyst
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We have developed the first user-friendly Negishi protocol capable of routinely cross-coupling all combinations of alkyl and aryl centers. The use of an easily synthesized, air stable, highly active, well-defined precatalyst PEPPSI-IPr (1; PEPPSI = pyridine-enhanced precatalyst preparation, stabilization and initiation; IPr = diisopropyl-phenylimidazolium derivative) substantially increases the scope, reliability, and ease-of-use of the Negishi reaction. All organohalides and routinely used pseudohalides were excellent coupling partners, with the use of chlorides, bromides, iodides, triflates, tosylates, and mesylates resulting in high yield of the coupled product. Furthermore, all reactions were performed by using general laboratory techniques, with no glove box necessary as the precatalyst was weighed and stored in air. Utilization of this methodology allowed for the easy synthesis of an assortment of sterically encumbered biaryls and druglike heteroaromatics, demonstrating the value of the PEPPSI-IPr system. Furthermore, this is also the first time Pd-NHC (NHC = N-heterocyclic carbene) methodology has surpassed the related phosphine-ligated Negishi processes both in activity and use.
- Organ, Michael G.,Avola, Stephanie,Dubovyk, Igor,Hadei, Niloufar,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Valente, Gory
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- Identification of a higher-order organozincate intermediate involved in Negishi cross-coupling reactions by mass spectrometry and NMR spectroscopy
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Negishi cross-coupling reactions were analyzed in solution by mass spectrometry and NMR spectroscopy to identify both the effect of LiBr as an additive as well as the purpose of 3-dimethyl-2-imidazolidinone (DMI) as a co-solvent. The results suggest that the main role of DMI is to facilitate a higher order bromozincate formation during the addition of LiBr. Copyright
- Hunter, Howard N.,Hadei, Niloufar,Blagojevic, Voislav,Patschinski, Pascal,Achonduh, George T.,Avola, Stephanie,Bohme, Diethard K.,Organ, Michael G.
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- Sonochemical, aerobic conversion of alkyl halides into alcohols promoted by trialkyltin halide/NaBH3CN catalytic system
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Under sonochemical conditions, various alkyl halides were converted into the corresponding alcohols in high yields through an aerobic radical reaction promoted by trialkyltin halide/NaBH3CN catalytic system.
- Sawamura, Masaya,Kawaguchi, Yasuhide,Sato, Kenichi,Nakamura, Eiichi
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- Thiol-Catalyzed Radical Decyanation of Aliphatic Nitriles with Sodium Borohydride
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Radical decyanation of aliphatic nitriles was achieved in the presence of NaBH4 and a thiol. The reaction proceeds via a radical mechanism involving borane radical anion addition to nitrile to form an iminyl radical, which undergoes carbon-carbon cleavage. Reductive radical addition to acrylonitrile is followed by decyanation to give a two-carbon homologated product in a net radical ethylation reaction.
- Kawamoto, Takuji,Oritani, Kyohei,Curran, Dennis P.,Kamimura, Akio
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- NHC-Iridium-Catalyzed Deoxygenative Coupling of Primary Alcohols Producing Alkanes Directly: Synergistic Hydrogenation with Sodium Formate Generated in Situ
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The direct conversion of alcohols into long-chain alkanes is an attractive but extremely challenging approach for biomass upgrading. Here, we describe the highly selective deoxygenative coupling of aryl ethanols with primary alcohols to produce alkanes, using a bis-N-heterocyclic carbene iridium (bis-NHC-Ir) complex as the catalyst. Up to quantitative yields and selectivity with a broad substrate scope are attained in both homo- and cross-coupling reactions. Mechanistic studies reveal that the further synergistic hydrogenation of the alkene intermediates by the formate generated in situ in the presence of bis-NHC-Ir is crucial for alkane production.
- Lu, Zeye,Zheng, Qingshu,Yang, Siqi,Qian, Chun,Shen, Yajing,Tu, Tao
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p. 10796 - 10801
(2021/09/08)
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- Ni-Catalyzed Aryl Sulfide Synthesis through an Aryl Exchange Reaction
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A Ni-catalyzed aryl sulfide synthesis through an aryl exchange reaction between aryl sulfides and a variety of aryl electrophiles was developed. By using 2-pyridyl sulfide as a sulfide donor, this reaction achieved the synthesis of aryl sulfides without using odorous and toxic thiols. The use of a Ni/dcypt catalyst capable of cleaving and forming aryl-S bonds was important for the aryl exchange reaction between 2-pyridyl sulfides and aryl electrophiles, which include aromatic esters, arenol derivatives, and aryl halides. Mechanistic studies revealed that Ni/dcypt can simultaneously undergo oxidative additions of aryl sulfides and aromatic esters, followed by ligand exchange between the generated aryl-Ni-SR and aryl-Ni-OAr species to furnish aryl exchanged compounds.
- Isshiki, Ryota,Kurosawa, Miki B.,Muto, Kei,Yamaguchi, Junichiro
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p. 10333 - 10340
(2021/07/21)
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- Tandem Acceptorless Dehydrogenative Coupling-Decyanation under Nickel Catalysis
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The development of new catalytic processes based on abundantly available starting materials by cheap metals is always a fascinating task and marks an important transition in the chemical industry. Herein, a nickel-catalyzed acceptorless dehydrogenative coupling of alcohols with nitriles followed by decyanation of nitriles to access diversely substituted olefins is reported. This unprecedented C=C bond-forming methodology takes place in a tandem manner with the formation of formamide as a sole byproduct. The significant advantages of this strategy are the low-cost nickel catalyst, good functional group compatibility (ether, thioether, halo, cyano, ester, amino, N/O/S heterocycles; 43 examples), synthetic convenience, and high reaction selectivity and efficiency.
- Babu, Reshma,Balaraman, Ekambaram,Midya, Siba P.,Subaramanian, Murugan,Yadav, Vinita
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p. 7552 - 7562
(2021/06/28)
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- Hydrodecyanation of Secondary Alkyl Nitriles and Malononitriles to Alkanes using DiMeImd-BH3
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The decyanation of secondary aliphatic nitriles and the 2-fold decyanation of malononitriles leading to alkanes in the presence of 1,3-dimethylimidazol-2-ylidene borane (diMeImd-BH3) are reported. These reactions proceed via a radical mechanism that involves the addition of a borane radical to the nitrile to form an iminyl radical, followed by cleavage of a carbon-carbon bond. Theoretical calculations suggest that the β-cleavage of these iminyl radicals, which affords NHC-BH2CN and the corresponding alkyl radicals, is the rate-determining step in this reaction.
- Kawamoto, Takuji,Oritani, Kyohei,Kawabata, Atsushi,Morioka, Tsubasa,Matsubara, Hiroshi,Kamimura, Akio
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p. 6137 - 6142
(2020/05/22)
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- Surface Modification of a Supported Pt Catalyst Using Ionic Liquids for Selective Hydrodeoxygenation of Phenols into Arenes under Mild Conditions
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The selective and efficient removal of oxygenated groups from lignin-derived phenols is a critical challenge to utilize lignin as a source for renewable aromatic chemicals. This report describes how surface modification of a zeolite-supported Pt catalyst using ionic liquids (ILs) remarkably increases selectivity for the hydrodeoxygenation (HDO) of phenols into arenes under mild reaction conditions using atmospheric pressure H2. Unmodified Pt/H-ZSM-5 converts phenols into aliphatic species as the major products along with a slight amount of arenes (10 % selectivity). In contrast, the catalyst modified with an IL, 1-butyl-3-methylimidazolium triflate, keeps up to 76 % selectivity for arenes even at a nearly complete conversion of phenols. The IL on the surface of Pt catalyst may offer the adsorption of phenols in an edge-to-face manner onto the surface, thus accelerating the HDO without the ring hydrogenation.
- Ohta, Hidetoshi,Tobayashi, Kanako,Kuroo, Akihiro,Nakatsuka, Mao,Kobayashi, Hirokazu,Fukuoka, Atsushi,Hamasaka, Go,Uozumi, Yasuhiro,Murayama, Haruno,Tokunaga, Makoto,Hayashi, Minoru
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supporting information
p. 14762 - 14766
(2019/11/13)
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- Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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- Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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p. 6312 - 6322
(2019/05/24)
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- Transition-Metal-Free Highly Chemoselective and Stereoselective Reduction with Se/DMF/H2O System
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A novel metal-free reduction system, in which H2Se (or HSe-) produced in situ from Se/DMF/H2O acts as the active reducing species, has been developed. By using water as an inexpensive, safe, and environmentally friendly surrogate as the hydrogen donor, this new reduction system incorporating Se/DMF/H2O displayed high selectivity and good activity in the reduction of α,β-unsaturated ketones and alkynes. Therefore, this reduction system has great potential to be a general and practical reduction methodology in organic transformation.
- Li, Hong-Chen,An, Cui,Wu, Ge,Li, Guo-Xing,Huang, Xiao-Bo,Gao, Wen-Xia,Ding, Jin-Chang,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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supporting information
p. 5573 - 5577
(2018/09/12)
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- Metathesis of renewable polyene feedstocks – Indirect evidences of the formation of catalytically active ruthenium allylidene species
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Cross-metathesis (CM) of conjugated polyenes, such as 1,6-diphenyl-1,3,5-hexatriene (1) and α-eleostearic acid methyl ester (2) with several olefins, including 1-hexene, dimethyl maleate and cis-stilbene as model compounds has been carried out using (1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene)-dichloro(o-isopropoxyphenylmethylene)ruthenium (Hoveyda-Grubbs 2nd generation, HG2) catalyst. The feasibility of these reactions is demonstrated by the observed high conversions and reasonable yields. Thus, regardless of the relatively low electron density, =CH–CH= conjugated units of molecules, including compound 2 as a sustainable, non-foodstuff source, can be utilized as building blocks for the synthesis of various value-added chemicals via olefin metathesis. DFT-studies and the product spectrum of the self-metathesis of 1,6-diphenyl-1,3,5-hexatriene suggest that a Ru η1-allylidene complex is the active species in the reaction.
- Kovács, Ervin,Sághy, Péter,Turczel, Gábor,Tóth, Imre,Lendvay, Gy?rgy,Domján, Attila,Anastas, Paul T.,Tuba, Róbert
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supporting information
p. 213 - 217
(2017/09/12)
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- Efficient phosphine-mediated formal C(sp3)-C(sp3) coupling reactions of alkyl halides in batch and flow
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The construction of C(sp3)-C(sp3) bond is an essential chemical transformation in synthetic chemistry due to its abundance in organic scaffolds. Here we demonstrate a valuable adaptation of the Wittig-type chemical procedure to efficiently facilitate C(sp3)-C(sp3) bond formation utilizing a range of alkyl building blocks. Additionally the method is amenable with flow synthesis to afford coupled products in good to excellent yields without laborious purification process.
- Tran,Hock,Gordon,Koenigs,Nguyen
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supporting information
p. 4950 - 4953
(2017/07/11)
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- Low-temperature and low-pressure non-oxidative activation of methane for upgrading heavy oil
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It is highly desirable to upgrade viscous heavy oil, such as bitumen extracted from Canadian oil sand, to be transportable by pipeline. Conventionally, this is achieved by expensive catalytic hydrogenation under a hydrogen pressure of 15-20 MPa. In this s
- Guo, Aijun,Wu, Chongchong,He, Peng,Luan, Yingqi,Zhao, Lulu,Shan, Wenpo,Cheng, Wei,Song, Hua
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p. 1201 - 1213
(2016/02/27)
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- Addition reactions of organometallic reagents to nitrogen trifluoride and enhanced alkyl-alkyl coupling by NF3
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A survey of the reaction of nitrogen trifluoride (NF3) with various organometallic reagents finds that organomagnesium (Grignard) reagents are the most useful for producing N,N-difluoroaminoalkanes. Alkyl-alkyl coupling is a persistant side reaction. Organolithiums are marginally effective. Organocopper, organozinc reagents undergo primarily alkyl-alkyl coupling catalyzed by the presence of NF3. Organocalcium and organoaluminum reagents are unreactive.
- Belter, Randolph K.
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p. 110 - 113
(2015/04/27)
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- Catalytic synthesis of n-alkyl arenes through alkyl group cross-metathesis
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n-Alkyl arenes were prepared in a one-pot tandem dehydrogenation/olefin metathesis/hydrogenation sequence directly from alkanes and ethylbenzene. Excellent selectivity was observed when (tBuPCP)IrH2 was paired with tungsten monoaryloxide pyrrolide complexes such as W(NAr)(C 3H6)(pyr)(OHIPT) (1a) [Ar = 2,6-i-Pr2C 6H3; pyr = pyrrolide; OHIPT = 2,6-(2,4,6-i-Pr 3C6H2)2C6H3O]. Complex 1a was also especially active in n-octane self-metathesis, providing the highest product concentrations reported to date. The thermal stability of selected olefin metathesis catalysts allowed elevated temperatures and extended reaction times to be employed.
- Dobereiner, Graham E.,Yuan, Jian,Schrock, Richard R.,Goldman, Alan S.,Hackenberg, Jason D.
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supporting information
p. 12572 - 12575
(2013/09/23)
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- Higher-order zincates as transmetalators in alkyl-alkyl Negishi cross-coupling
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Negishi revisited: Higher-order alkyl zincates have been subjected to Negishi coupling with alkyl bromides. For the first time, coupling takes place in straight THF, i.e., without a salt additive and a high dielectric co-solvent. This provides evidence that it is the higher-order zincate that undergoes transmetalation to Pd, and not mono-anionic zincates or any of the other species present in the Schlenk equilibrium. Copyright
- McCann, Lucas C.,Hunter, Howard N.,Clyburne, Jason A. C.,Organ, Michael G.
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supporting information; experimental part
p. 7024 - 7027
(2012/10/18)
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- Selective palladium-loaded MIL-101 catalysts
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Palladium nanoparticles (NPs) of different mean particle size have been synthesized in the host structure of the porous coordination polymer (or metal-organic framework: MOF) MIL-101. The metal-organic chemical vapor deposition method was used to load MIL-101 with the Pd precursor complex [(η5-C5H5)Pd(η3-C 3H5)]. Loadings higher than 50 wt.% could be accomplished. Reduction of the Pd precursor complex with H2 gave rise to Pd NPs inside the MIL-101 (Pd@MIL-101). The reduction conditions, especially the temperature, allows us to make size-conform (size of the Pd NPs correlates with the size of the cavities of the host structure of MIL-101) and undersized Pd NPs. The Pd@MIL-101 samples were characterized by X-ray diffraction, IR spectroscopy, Brauner-Emmett-Teller (BET) analysis, elemental analysis, and transmission electron microscopy (TEM). Catalytic studies, hydrogenation of ketones, were performed with selected Pd@MIL-101 catalysts. Activity, selectivity, and recyclability of the catalyst family are discussed.
- Hermannsdoerfer, Justus,Kempe, Rhett
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experimental part
p. 8071 - 8077
(2011/09/12)
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- Reactivity of mixed organozinc and mixed organocopper reagents: 6. Nickel-catalyzed coupling of methylarylzincs with primary alkyl halides; An atom-economic aryl-alkyl coupling
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A nickel-catalyzed process for the cross-coupling of mixed arylzincs and primary alkyl halides has been developed. The reaction of a methylarylzinc with a primary alkyl halide in THF in the presence of NiCl2/PPh 3 takes place with selective aryl transfer at room temperature in moderate yields. This protocol provides an atom-economic alternative to aryl-primary alkyl coupling using diarylzincs.
- Pekel, ?zgen ?mür,Erdik, Ender
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experimental part
p. 7087 - 7090
(2012/01/06)
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- Structure-activity relationship analysis of Pd-PEPPSI complexes in cross-couplings: A close inspection of the catalytic cycle and the precatalyst activation model
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A series of Pd-N-heterocyclic carbene (Pd-NHC) complexes with various NHC, halide and pyridine ligands (PEPPSI (pyridine, enhanced, precatalyst, preparation, stabilisation and initiation) precatalysts) were prepared, and the effects of these ligands on catalyst activation and performance were studied in the Kumada-TamaoCorriu (KTC), Negishi, and Suzuki-Miyaura cross-coupling reactions. The lowered reactivity of more hindered 2,6-dimethylpyridyl complex 4 in the Negishi and KTC reactions is consistent with slow reductive dimerisation of the organometallic reaction partner during precatalyst activation. Comparative rate studies of complexes 1, 4 and 5 in the KTC and Suzuki-Miyaura reactions verify that 4 activated more slowly than the others. A potential on/ off mechanism of pyridine coordination to NHC-Pd0 is also plausible, in which the more basic pyridine stays bound for longer.
- Nasielski, Joanna,Hadei, Nilofaur,Achonduh, George,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Lough, Alan,Organ, Michael G.
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supporting information; scheme or table
p. 10844 - 10853
(2010/12/19)
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- Negishi alkyl-aryl cross-coupling catalyzed by Rh: Efficiency of novel tripodal 3-diphenylphosphino-2-(diphenylphosphino)methyl-2-methylpropyl acetate ligand
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3-Diphenylphosphino-2-(diphenylphoshino)methyl-2-methylpropyl acetate acted as an efficient ligand for a Rh catalyst, achieving cross-coupling between arylzinc compounds bearing electron-withdrawing groups and alkyl electrophiles. The beneficial effect of the tripodal ligand and such aryl nucleophiles was discussed with regard to the specificity of the Rh catalysis.
- Ejiri, Syogo,Odo, Shunsuke,Takahashi, Hideki,Nishimura, Yugo,Gotoh, Kazuma,Nishihara, Yasushi,Takagi, Kentaro
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supporting information; experimental part
p. 1692 - 1695
(2010/09/03)
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- Liquid-crystalline polymorphism of symmetrical azobananas: Bis(4-(4-alkylphenyl)azophenyl) 2-nitroisophtalates
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In this paper we present a series of novel compounds, bis(4-(4-alkylphenyl) azophenyl) 2-nitroisophtalates, which exhibit nematic and banana-type liquidcrystalline phases. The alkyl chain length varies from 1 to 18 carbons. The first ten members of this series exhibit nematic phase. The last eleven compounds exhibit banana-type liquid crystalline phases. The propyl and pentyl derivatives have extra second type of banana mesophase. Copyright Taylor & Francis Group, LLC.
- Zygadlo,Dardas,Nowicka,Hofmann,Galewski
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p. 283 - 291
(2011/08/02)
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- Density functional theory investigation of the Alkyl-aikyl negishi Cross-coupling reaction catalyzed by N-heterocyclic carbene (NHC)-Pd complexes
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A novel mechanism is proposed for the Pd-1,3-(2,6-diisopropyl-phenyl) imidazolyl-2-ylidene (1) catalyzed Negishi reaction. DFT computations supported by atoms-in-molecules (AIM) analyses of non-truncated models show that a "steric wall" created by the iV-
- Chass, Gregory A.,O'Brien, Christopher J.,Hadei, Niloufar,Kantchev, Eric Assen B.,Mu, Wei-Hua,Fang, De-Cai,Hopkinson, Alan C.,Csizmadia, Imre G.,Organ, Michael G.
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experimental part
p. 4281 - 4288
(2009/12/07)
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- Synergistic effects of alkali metals in the alkylation of naphthalene and toluene with ethene in the ArH-alkali metal systems in THF (ArH - naphthalene, phenanthrene)
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The use of mixtures of metallic lithium and sodium in the naphthalene-alkali metal systems in THF leads to a synergistic acceleration of the naphthalene alkylation with ethene at room temperature and atmospheric pressure. The greatest synergistic effect is observed at a Li:Na molar ratio of 2:1. Under these conditions, the overall conversion of naphthalene into alkylation products (linear 1-alkylnaphthalenes and their dihydro derivatives) attains 88% after 24 h (a (Li + Na):C10H8 ratio is 2:1). The use of mixtures of metallic lithium and potassium in such systems results, however, in a synergistic retardation of the alkylation process. The strongest retarding effect is observed at a Li:K molar ratio of 1:1. The efficiency of the toluene alkylation with ethene in the naphthalene-alkali metal systems in THF is also increased on the replacement of lithium or sodium by their mixtures. The best results are obtained at a Li:Na molar ratio of 1:3. With this Li:Na ratio, toluene is almost quantitatively converted into linear and α-branched higher monoalkylbenzenes (24 h, (Li + Na):C10H8 = 2:1). The rate of the naphthalene alkylation with ethene in the presence of toluene is enhanced as well on an introduction of mixtures of lithium and sodium into the system. However the maximum of the activity is shifted here towards higher lithium content (Li:Na = 1:1). A similar synergistic effect of lithium and sodium was found on studying the toluene alkylation with ethene in the phenanthrene-Li-Na systems in THF (a (Li + Na):phenanthrene ratio is 3:1). An addition of potassium to sodium also considerably increases the efficiency of the toluene and naphthalene alkylation with ethene in the naphthalene-based systems. The possible mechanism of the alkali metal synergism in the above-mentioned alkylation reactions is discussed.
- Rummel,Yunusov,Kalyuzhnaya,Shur
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experimental part
p. 1467 - 1472
(2009/09/06)
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- Activation of C-H bonds of hydrocarbons by the ArH-alkali metal systems in THF (ArH - naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene, pyrene). Alkylation of naphthalene and toluene with ethene
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Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this reaction is exhibited by the naphthalene-potassium system which converts naphthalene into 1-ethylnaphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h, K:C10H8 = 2:1). The same alkylation products are formed when metallic sodium is used instead of potassium. The interaction of ethene with the naphthalene-lithium system (24 h, Li:C10H8 = 2:1) affords 1 together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5), 1-n-oktylnaphthalene (6) and dihydro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphthalene-alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C10H8 = 2:1), in the presence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of toluene with ethene at 22 °C. Of particularly active is the stilbene-lithium system (Li:stilbene = 3:1) which converts toluene into a mixture of 11-14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal. The mechanism of the reactions found is discussed.
- Rummel,Ilatovskaya,Yunusov,Kalyuzhnaya,Shur
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scheme or table
p. 1459 - 1466
(2009/09/06)
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- Transition metal complexes of N-heterocyclic carbenes, method of preparation and use in transition metal catalyzed organic transformations
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The present invention relates to catalysts of transition metal complexes of N-heterocyclic carbenes, their methods of preparation and their use in chemical synthesis. The synthesis, ease-of-use, and activity of the compounds of the present invention are substantial improvements over in situ catalyst generation. Further, the transition metal complexes of N-heterocyclic carbenes of the present invention may be used as precatalysts in metal-catalyzed cross-coupling reactions.
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Page/Page column 10; 15
(2010/11/26)
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- N-isopropylidene-N′-2-nitrobenzenesulfonyl hydrazine, a reagent for reduction of alcohols via the corresponding monoalkyl diazenes
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The reagent N-isopropylidene-N′-2-nitrobenzenesulfonyl hydrazine (IPNBSH) is used in the reduction of alcohols via the loss of dinitrogen from transiently formed monoalkyl diazene intermediates accessed by sequential Mitsunobu displacement, hydrolysis, and fragmentation under mild reaction conditions.
- Movassaghi, Mohammad,Ahmad, Omar K.
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p. 1838 - 1841
(2007/10/03)
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- PROCESS FOR PRODUCING PHOSPHONIUM BORATE COMPOUND, NOVEL PHOSPHONIUM BORATE COMPOUND, AND METHOD OF USING THE SAME
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The invention relates to a phosphonium borate compound represented by Formula (I) (hereinafter, the compound (I)). The invention has objects of providing (A) a novel process whereby the compound is produced safely on an industrial scale, by simple reaction operations and in a high yield; (B) a novel compound that is easily handled; and (C) novel use as catalyst. ????????Formula (I) : (R1)(R2)(R3)PH·BAr4?????(I) wherein R1, R2, R3 and Ar are as defined in the specification. The process (A) includes reacting a phosphine with a) HCl or b) H2SO4 to produce a) a hydrochloride or b) a sulfate; and reacting the salt with a tetraarylborate compound. The compound (B) has for example a secondary or tertiary alkyl group as R1 and is easily handled in air without special attention. The use (C) is characterized in that the compound (I) is used instead of an unstable phosphine compound of a transition metal complex catalyst for catalyzing C-C bond, C-N bond and C-O bond forming reactions and the compound produces an effect that is equal to that achieved by the transition metal complex catalyst.
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Page/Page column 81
(2008/06/13)
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- Easily prepared air- and moisture-stable Pd-NHC (NHC = N-heterocyclic carbene) complexes: A reliable, user-friendly, highly active palladium precatalyst for the Suzuki-Miyaura reaction
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The synthesis of NHC-PdCl2-3-chloropyridine (NHC = N-heterocyclic carbene) complexes from readily available starting materials in air is described. The 2,6-diisopropylphenyl derivative was found to be highly catalytically active in alkyl-alkyl Suzuki and Negishi cross-coupling reactions. The synthesis, ease-of-use, and activity of this complex are substantial improvements over in situ catalyst generation and all current Pd-NHC complexes. The utilization of complex 4 led to the development of a reliable, easily employed Suzuki-Miyama protocol. Employing various reaction conditions allowed a large array of hindered biaryl and drug-like heteroaromatic compounds to be synthesized without difficulty.
- O'Brien, Christopher J.,Kantchev, Eric Assen B.,Valente, Cory,Hadei, Niloufar,Chass, Gregory A.,Lough, Alan,Hopkinson, Alan C.,Organ, Michael G.
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p. 4743 - 4748
(2008/02/08)
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- Towards the rational design of palladium-N-heterocyclic carbene catalysts by a combined experimental and computational approach
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A combined experimental and computational approach towards the development of Pd-NHC catalysts is described. A range of benzimidazolylidinium ligands incorporating electron-rich and electron-poor substituents were prepared and evaluated in the Suzuki reaction. The most electron-rich ligand showed the highest catalytic activity. Based on this information, the first alkyl-alkyl Negishi cross-coupling reaction protocol was developed. Evaluation of N,N′-diaryl-(4,5-dihydro)imidazolylilidinium ligands showed a strong dependence on the steric topography around the metal centre. A computational study of the most active ligand in the Negishi reaction, its Pd(0) and PdCl 2-complexes and related structures were modelled at the B3LYP/DZVP and HF/3-21G levels of theory. The potential energy hypersurfaces flattened with increase in ligand size. Binding energies were computed for carbene/Pd(0) adducts (in the range ～31-40 kcal mol-1), roughly double that for PH3 (～16 kcal mol-1). Weak intramolecular interactions were found using AIM analyses.
- O'Brien, Christopher J.,Kantchev, Eric Assen B.,Chass, Gregory A.,Hadei, Niloufar,Hopkinson, Alan C.,Organ, Michael G.,Setiadi, David H.,Tang, Ting-Hua,Fang, De-Cai
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p. 9723 - 9735
(2007/10/03)
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- Room-temperature Negishi cross-coupling of unactivated alkyl bromides with alkyl organozinc reagents utilizing a Pd/N-heterocyclic carbene catalyst
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A high-yielding cross-coupling reaction of unactivated alkyl bromides possessing β-hydrogens with alkylzinc halides utilizing a Pd/N-heterocyclic carbene (NHC) catalyst at room temperature is described. A variety of Pd sources, Pd2(dba)3, Pd(OAc)2, or PdBr 2, with the commercially available ligand precursor 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (IPr·HCl) successfully coupled 1-bromo-3-phenylpropane with n-butylzinc bromide in THF/NMP. An investigation of different NHC precursors showed that the bulky 2,6-diisopropylphenyl moiety was necessary to achieve high coupling yields (75-85%). The corresponding ethyl analogue was moderately active (11%). A range of unsymmetrical NHC precursors were prepared and evaluated. The ligand precursor containing one 2,6-diisopropylphenyl and one 2,6-diethylphenyl afforded the coupling product in 47% yield, clearly suggesting a direct relationship between the steric topography created by the flanking N-substituents and catalyst activity. Under optimal conditions, a number of alkyl bromides and alkylzinc halides possessing common functional groups (amide, nitrile, ester, acetal, and alkyne) were effectively coupled (61-92%). It is noteworthy that β-substituted alkyl bromides and alkylzinc halides successfully underwent cross-coupling. Also, under these conditions alkyl chlorides were unaffected.
- Hadei, Niloufar,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Organ, Michael G.
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p. 8503 - 8507
(2007/10/03)
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- The first Negishi cross-coupling reaction of two alkyl centers utilizing a Pd-N-heterocyclic carbene (NHC) catalyst
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(Chemical Equation Presented) The development of an NHC-based system capable of cross-coupling sp3-sp3 centers in high yield has been a long-standing challenge. This communication describes the use of a Pd-NHC catalytic system that achieves room-temperature Negishi cross-couplings of unactivated, primary bromides and alkyl organozinc reagents with a variety of functionality.
- Hadei, Niloufar,Kantchev, Eric Assen B.,O'Brien, Christopher J.,Organ, Michael G.
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p. 3805 - 3807
(2007/10/03)
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- Reductive cleavage of 1,3-dithiane systems anchored on polymers useful for supported organic syntheses
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Completely odourless reductions of ketones to alkanes through condensation with 1,3-propanedithiol copolymers and cleavage of the formed 1,3-dithiane units with sodium and ammonia or tributyltin hydride and AIBN, useful as a new synthetic methodology for combinatorial chemistry, is reported. Selective reductions of ketones in presence of an ester or a second ketone group are exemplified.
- Bertini, Vincenzo,Lucchesini, Francesco,Pocci, Marco,Alfei, Silvana,De Munno, Angela
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p. 1201 - 1203
(2007/10/03)
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- A real time reaction monitoring using fluorescent dansyl group as a solid-phase leaving group
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A real time monitoring method to monitor the progress of the solid-phase reaction has been developed. The substitution reaction on the solid-phase was clearly monitored as a change in the color depth using the fluorescent dansyl group as the leaving group. This methodology is applicable to both parallel and split combinatorial synthesis.
- Suenaga, Toshiro,Schutz, Caroline,Nakata, Tadashi
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p. 5799 - 5801
(2007/10/03)
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- Pd-Catalyzed Cross-Coupling Reaction of Alkyl Tosylates and Bromides with Grignard Reagents in the Presence of 1,3-Butadiene
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A new method for cross-coupling reaction of alkyl tosylates and bromides with Grignard reagents has been developed by the use of Pd(acac)2 or PdCl2 as the catalyst. Addition of 1,3-butadiene is essential to afford good yields of coupling products. This reaction proceeds efficiently at room temperature using primary and secondary alkyl and aryl Grignard reagents.
- Terao, Jun,Naitoh, Yoshitaka,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 890 - 891
(2007/10/03)
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- Rapid defunctionalization of carbonyl group to methylene with polymethylhydrosiloxane-B(C6F5)3
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The polymethylhydrosiloxane-B(C6F5)3 combination is found to be a versatile carbonyl defunctionalization system under mild and rapid conditions. For the first time, B(C6F5)3 has been used as a nonconventional Lewis acid catalyst to activate PMHS. Aromatic and aliphatic carbonyl compounds were effectively reduced to give the corresponding alkanes in high yields.
- Chandrasekhar,Raji Reddy, Ch.,Nagendra Babu
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p. 9080 - 9082
(2007/10/03)
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- Discotic liquid crystals of transition metal complexes, 31: Establishment of mesomorphism and thermochromism of bis[1,2-bis(4-n-alkoxyphenyl)ethane-1,2-dithiolene]nickel complexes
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Two series of bis[1,2-bis(4-n-alkylphenyl)ethane-1,2-dithiolene]nickel, Cn-Ni (n= 1-12), and bis[1,2-bis(4-n-alkoxyphenyl)ethane-1,2-dithiolene]nickel, CnO-Ni(n = 1-12, 14, 16, 18), have been synthesized. Their mesomorphism, thermochromism, supramolecular structures and π-acceptor property have been investigated by using different scanning calorimetry, polarizing microscopy, temperature-dependent X-ray diffraction technique, electronic spectroscopy and cyclic voltammetry. From the X-ray diffraction and electronic spectral results, it was established that the CnO-Ni complexes for n ≤ 10 exhibit two differently colored discotic lamellar (DL) mesophases whereas none of the Cn-Ni complexes has a mesophase, and that the thermochromism (brown→green) is attributable to a slow transformation from the Ni-Ni bonded dimers to the Ni-S bonded dimers.
- Horie,Takagi,Hasebe,Ozawa,Ohta
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p. 1063 - 1071
(2007/10/03)
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- Scope and utility of a new soluble copper catalyst [CuBr-LiSPh-LiBr-THF]: A comparison with other copper catalysts in their ability to couple one equivalent of a Grignard reagent with an alkyl sulfonate
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A mixture of equal amounts of CuBr-SMe2, LiBr, and LiSPh in THF at 0°C furnished a new soluble copper catalyst that was highly efficient at coupling primary, secondary, tertiary, aryl, vinyl, and allylic Grignard reagents to primary tosylates and primary Grignard reagents to secondary tosylates and mesylates, all with the use of only 1 equiv of Grignard reagent. The new catalyst was shown to be much more reactive than copper catalysts CuBr and Li2CuCl4 and more efficient in the transference of secondary and tertiary alkyl groups than lower order cuprates (Gilman reagents) and demonstrated more reactivity than the lower order cuprates with its ability to couple primary Grignard reagents to secondary sulfonates. The Grignard reagent/catalyst system was compatible with an ester functionalized tosylate, thus proving to be more chemoselective than a Grignard reagent without the catalyst. The catalyst exhibited good reactivity below room temperature, and with the addition of 6% v/v of HMPA to the catalyst solution, excellent yields of coupled product were obtained within a 25-67°C temperature range. 1H NMR demonstrated that the catalyst solution consisted of several species that most likely were composed of copper ligated with thiophenol, THF, and LiBr in aggregated forms.
- Burns, Dennis H.,Miller, Jeffrey D.,Chan, Ho-Kit,Delaney, Michael O.
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p. 2125 - 2133
(2007/10/03)
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- Structure-activity relationships for the antileishmanial and antitrypanosomal activities of 1'-substituted 9-anilinoacridines
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Members of the class of 9-anilinoacridine topoisomerase II inhibitors bearing lipophilic electron-donating 1'-aniline substituents are active against both the promastigote and amastigote forms of the parasite Leishmania major. A series of analogues of the known 1'-NHhexyl lead compound were prepared and evaluated against L. major in macrophage culture to further develop structure-activity relationships (SAR). Toxicity toward mammalian cells was measured in a human leukemia cell line, and the ratio of the two IC50 values (IC50(J)/IC50(L)) was used as a measure of the in vitro therapeutic index (IVTI). A 3,6-diNMe2 substitution pattern on the acridine greatly increased toxicity to L. major without altering mammalian toxicity, increasing IVTIs over that of the lead compound. The 2-OMe, 6-C1 acridine substitution pattern used in the antimalarial drug mepacrine also resulted in potent antileishmanial activity and high IVTIs. Earlier suggestions of the utility of 2'-OR groups in lowering mammalian cytotoxicity were not borne out in this wider study. A series of very lipophilic 1'-NRR (symmetric dialkylamino)-substituted analogues showed relatively high antileishmanial potency, but no clear trend was apparent across the series and none were superior to the 1'-NH(CH2)5Me subclass. Subsets of the most active 1'- N(R)(CH2)5Me- and 1'-N(alkyl)2-substituted compounds against L. major were also evaluated against Leishmania donovani, Trypanosoma cruzi, and Trypanosoma brucei, but no consistent SAR could be discerned in these physiologically diverse test systems. The present study has confirmed earlier conclusions that lipophilic electron-donating groups at the 1'-position of 9- anilinoacridines provide high activity against L. major, but the SAR patterns observed do not carry over to the other parasites studied.
- Gamage, Swarna A.,Figgitt, David P.,Wojcik, Stanley J.,Ralph, Raymond K.,Ransijn, Adriana,Mauel, Jacques,Yardley, Vanessa,Snowdon, Diane,Croft, Simon L.,Denny, William A.
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p. 2634 - 2642
(2007/10/03)
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- Desulfurization with Nickel and Cobalt Boride: Scope, Selectivity, Stereochemistry, and Deuterium-Labeling Studies
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A variety of organosulfur compounds containing alkylthio and arylthio groups underwent reductive desulfurization under notably mild conditions when treated with nickel boride, generated in situ from nickel chloride hexahydrate and sodium borohydride in methanol-THF (3:1).Phenyl, chloro, and ester groups are not reduced under these conditions, while iodo, bromo, nitrile, aldehyde, ketone, cyclopropane, and olefinic functions are reduced either completely or partially.Deuterium-labeling studies indicate that the hydrogen that is incorporated into the product originates from both the sodium borohydride and the protic solvent, suggesting the intermediacy of dihydrogen.The epimers 3α- and 3β-(phenylthio)cholestane afforded 3α- and 3β-deuteriocholestane, respectively, demonstrating that the reaction proceeds with retention of configuration.The method may thus be employed for the stereospecific preparation of deuterated products from organosulfur compounds.Arguments are presented in support of a tentative mechanism involving an oxidative addition-reductive elimination sequence via a nickel hydride intermediate.
- Back, Thomas G.,Baron, Denise L.,Yang, Kexin
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p. 2407 - 2413
(2007/10/02)
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- A Novel, Chemoselective, "One-pot" Procedure for the Simultaneous Denitration-Deoxygenation of 2-Nitroketones by TsNHNH2-NaBH4
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Chemoselective conversion of both the carbonyl group and the carbon bearing the nitro group, of 2-nitro ketones, into two methylenes is performed in one-pot, under mild conditions.
- Ballini, Roberto,Castagnani, Roberto,Marcantoni, Enrico
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p. 3161 - 3162
(2007/10/02)
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- HOMOLYTIC ADDITION OF BENZYL BROMIDE TO UNSATURATED COMPOUNDS IN CONDITIONS OF METAL-COMPLEX INITIATION
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Radical addition of benzyl bromide to unsaturated compounds containing substituents of a different polar nature, CH2=CHX (X = C4H9, SiMe3, CF3, CO2Me, CN, H), was conducted in the presence of the Fe(CO)5 + DMF (HMPA) system.Adducts were obtained and their structure was demonstrated by 13C NMR and mass spectrometry.Keywords: homolytic addition, benzyl bromide, unsaturated compounds, iron pentacarbonyl, DMF, HMPA.
- Vasil'eva, T. T.,Gapusenko, S. I.,Vitt, S. V.,Terent'ev, A. B.
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p. 1841 - 1845
(2007/10/02)
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