- Catalytic Intermolecular C(sp3)-H Amination: Selective Functionalization of Tertiary C-H Bonds vs Activated Benzylic C-H Bonds
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A catalytic intermolecular amination of nonactivated tertiary C(sp3)-H bonds (BDE of 96 kcal·mol-1) is reported for substrates displaying an activated benzylic site (BDE of 85 kcal·mol-1). The tertiary C(sp3)-H bond is selectively functionalized to afford α,α,α-Trisubstituted amides in high yields. This unusual site-selectivity results from the synergistic combination of Rh2(S-Tfpttl)4, a rhodium(II) complex with a well-defined catalytic pocket, with tert-butylphenol sulfamate (TBPhsNH2), which leads to a discriminating rhodium-bound nitrene species under mild oxidative conditions. This catalytic system is very robust, and the reaction was performed on a 50 mmol scale with only 0.01 mol % of catalyst. The TBPhs group can be removed under mild conditions to afford the corresponding NH-free amines.
- Brunard, Erwan,Boquet, Vincent,Van Elslande, Elsa,Saget, Tanguy,Dauban, Philippe
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supporting information
p. 6407 - 6412
(2021/05/29)
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- Halogen-Bridged Methylnaphthyl Palladium Dimers as Versatile Catalyst Precursors in Coupling Reactions
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Halogen-bridged methylnaphthyl (MeNAP) palladium dimers are presented as multipurpose Pd-precursors, ideally suited for catalytic method development and preparative organic synthesis. By simply mixing with phosphine or carbene ligands, they are in situ converted into well-defined monoligated complexes. Their catalytic performance was benchmarked against state-of-the-art systems in challenging Buchwald–Hartwig, Heck, Suzuki and Negishi couplings, and ketone arylations. Their use enabled record-setting activities, beyond those achievable by optimization of the ligand alone. The MeNAP catalysts permit syntheses of tetra-ortho-substituted arenes and bulky anilines in near-quantitative yields at room temperature, allow mono-arylations of small ketones, and enable so far elusive cross-couplings of secondary alkyl boronic acids with aryl chlorides.
- Doppiu, Angelino,Goo?en, Lukas J.,Hu, Zhiyong,Pirkl, Nico,Sivendran, Nardana
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supporting information
p. 25151 - 25160
(2021/10/19)
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- Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents
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Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C?C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2?Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
- Dilchert, Katharina,Gessner, Viktoria H.,Gro?johann, Angela,Rodstein, Ilja,Scherpf, Thorsten,Steinert, Henning,Tappen, Jens
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supporting information
p. 20596 - 20603
(2020/09/09)
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- Bioinspired Metal-Free Formal Decarbonylation of α-Branched Aliphatic Aldehydes at Ambient Temperature
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A sequence of a Baeyer–Villiger oxidation and a Lewis acid-promoted reduction of the resulting formate with Et3SiH enabled the metal-free formal decarbonylation of tertiary and secondary aliphatic aldehydes. The new methodology mimics the biosynthetic decarbonylation pathway through oxidative C?C bond cleavage rather than the C(O)?H bond activation known from conventional Tsuji–Wilkinson-type reactions. The substrate scope is complementary to existing transition-metal-catalyzed protocols.
- Richter, Sven C.,Oestreich, Martin
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p. 8508 - 8512
(2019/06/04)
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- Terminal-Selective Functionalization of Alkyl Chains by Regioconvergent Cross-Coupling
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Hydrocarbons are still the most important precursors of functionalized organic molecules, which has stirred interest in the discovery of new C?H bond functionalization methods. We describe herein a new step-economical approach that enables C?C bonds to be constructed at the terminal position of linear alkanes. First, we show that secondary alkyl bromides can undergo in situ conversion into alkyl zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross-coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross-coupling then provided access to the corresponding linear arylation product in only two steps.
- Dupuy, Stéphanie,Zhang, Ke-Feng,Goutierre, Anne-Sophie,Baudoin, Olivier
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supporting information
p. 14793 - 14797
(2016/11/23)
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- An N-heterocyclic carbene-based nickel catalyst for the Kumada–Tamao–Corriu coupling of aryl bromides and tertiary alkyl Grignard reagents
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In this study, nickel-catalyzed coupling reactions between arylhalides and tert-alkyl Grignard reagents were developed. Our original bicyclic NHC ligands reduced the formation of isomerized products, and we found that NMP as a co-solvent suppressed the reduction process. Under the optimal conditions we developed, the catalyst loading was lowered to 0.5?mol?%, and catalyst loading using ortho-substituted aryl bromides was also applicable at the level of 2.0?mol?%.
- Ando, Shin,Mawatari, Mai,Matsunaga, Hirofumi,Ishizuka, Tadao
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supporting information
p. 3287 - 3290
(2016/07/11)
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- An unprecedented iron-catalyzed cross-coupling of primary and secondary alkyl Grignard reagents with non-activated aryl chlorides
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The use of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling of alkyl Grignards has allowed, for the first time, coupling of non-activated, electron rich aryl chlorides. Surprisingly, the tetrahydrate of FeCl2 was found to be a better pre-catalyst than anhydrous FeCl 2. Primary Grignard reagents coupled in excellent yields while secondary Grignard reagents coupled in modest yields. The use of acyclic secondary Grignard reagents resulted in the formation of isomers in addition to the desired product. These isomeric products were formed via reversible β-hydrogen elimination, indicating that the cross-coupling proceeds through an ionic pathway.
- Perry, Marc C.,Gillett, Amber N.,Law, Tyler C.
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experimental part
p. 4436 - 4439
(2012/09/25)
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- Cross-coupling of non-activated chloroalkanes with aryl grignard reagents in the presence of iron/N-heterocyclic carbene catalysts
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An efficient and high-yielding cross-coupling reaction of various primary, secondary, and tertiary alkyl chlorides with aryl Grignard reagents was achieved by using catalytic amounts of N-heterocyclic carbene ligands and iron salts. This reaction is a simple and efficient arylation method having applicability to a wide range of industrially abundant chloroalkanes, including polychloroalkanes, which are challenging substrates under conventional cross-coupling conditions.
- Ghorai, Sujit K.,Jin, Masayoshi,Hatakeyama, Takuji,Nakamura, Masaharu
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supporting information; experimental part
p. 1066 - 1069
(2012/04/10)
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- 7-(Piperazine-1-Ymethyl)-1H-Indole-2-Carboxylic Acid (Phenyl)-Amide Derivatives and Allied Compounds as P38 Map Kinase Inhibitors for the Treatment of Respiratory Diseases
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The present invention provides compounds according to general formula (I) which are proposed for the treatment of respiratory complaints, particularly asthma and COPD.
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- Nickel-catalyzed cross-coupling of aryl bromides with tertiary grignard reagents utilizing donor-functionalized N-heterocyclic carbenes (NHCs)
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Metal-catalyzed cross-coupling reactions are among the most important transformations in organic synthesis, allowing the efficient construction of complex structures from simpler, readily available building blocks.Many applications in large and small-scale synthesis can be found in different areas such as agrochemicals, pharmaceuticals and supramolecular chemistry. Whereas the coupling of sp2-hybridized carbon atoms in either reaction partner is well established, the use of CACHTUNGTRENUNG(sp3)-hybridized substrates presents some challenges. Catalytic cross-coupling of sterically hindered tertiary alkyl substrates is especially difficult, generally resulting in low yields, and thus, only few reports exist.[27] A big challenge in this field is not only to get the required level of reactivity, but also to overcome competing pathways like β-hydride elimination, hydrodehalogenation or isomerization
- Lohre, Claudia,Droege, Thomas,Wang, Congyang,Glorius, Frank
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scheme or table
p. 6052 - 6055
(2011/06/25)
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- Palladium-catalyzed cross-coupling of cyclopropylmagnesium bromide with aryl bromides mediated by zinc halide additives
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The key Pd-catalyzed cross-coupling of aryl bromides or triflates and cyclopropylmagnesium bromide in the presence of substoichiometric amounts of zinc bromide produces cyclopropyl arenes in good to excellent yields. The cross-coupling of other alkyl, cyc
- Shu, Chutian,Sidhu, Kanwar,Zhang, Li,Wang, Xiao-Jun,Krishnamurthy, Dhileepkumar,Senanayake, Chris H.
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experimental part
p. 6677 - 6680
(2010/12/19)
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- Suzuki-miyaura cross-coupling reactions of primary alkyltrifluoroborates with aryl chlorides
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(Chemical Equation Presented) Parallel microscale experimentation was used to develop general conditions for the Suzuki-Miyaura cross-coupling of diversely functionalized primary alkyltrifluoroborates with a variety of aryl chlorides. These conditions wer
- Dreher, Spencer D.,Lim, Siang-Ee,Sandrock, Deidre L.,Molander, Gary A.
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supporting information; experimental part
p. 3626 - 3631
(2009/09/29)
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- Functional group tolerant Kumada-Corriu-Tamao coupling of nonactivated alkyl halides with aryl and heteroaryl nucleophiles: Catalysis by a nickel pincer complex permits the coupling of functionalized Grignard reagents
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A nickel(II) pincer complex [(MeNN2)NiCl] (1) catalyzes Kumada-Corriu-Tamao cross coupling of nonactivated alkyl halides with aryl and heteroaryl Grignard reagents. The coupling of octyl bromide with phenylmagnesium chloride was used as a test reaction. Using 3 mol % of 1 as the precatalyst and THF as the solvent, and in the presence of a catalytic amount of TMEDA, the coupling product was obtained in a high yield. The reaction conditions could be applied to cross coupling of other primary and secondary alkyl bromides and iodides. The coupling is tolerant to a wide range of functional groups. Therefore, alkyl halides containing ester, amide, ether, thioether, alcohol, pyrrole, indole, furan, nitrile, conjugated enone, and aryl halide moieties were coupled to give high isolated yields of products in which these units stay intact. For the coupling of ester-containing substrates, O-TMEDA is a better additive than TMEDA. The reaction protocol proves to be efficient for the coupling of Knochel-type functionalized Grignard reagents. Thus aryl Grignard reagents containing electron-deficient and/or sensitive ester, nitrile, amide, and CF3 substituents could be successfully coupled to nonactivated and functionalized alkyl iodides. The catalysis is also efficient for the coupling of alkyl iodides with functionalized heteroaryl Grignard reagents, giving rise to pyridine-, thiophene-, pyrazole-, furan-containing molecules with additional functionalities. Concerning the mechanism of the catalysis, [(MeNN2)Ni-(hetero)Ar] was identified as an intermediate, and the activation of alkyl halides was found to take place through a radical-rebound process.
- Vechorkin, Oleg,Proust, Valerie,Hu, Xile
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supporting information; experimental part
p. 9756 - 9766
(2011/03/19)
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- Structure-activity relationships for a novel series of thiazolyl phenyl ether derivatives exhibiting potent and selective acetyl-CoA carboxylase 2 inhibitory activity
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Structure-activity relationships for a recently discovered thiazolyl phenyl ether series of acetyl-CoA carboxylase (ACC) inhibitors were investigated. Preliminary efforts to optimize the series through modification of the distal aryl ether moiety of the l
- Clark, Richard F.,Zhang, Tianyuan,Xin, Zhili,Liu, Gang,Wang, Ying,Hansen, T. Matthew,Wang, Xiaojun,Wang, Rongqi,Zhang, Xiaolin,Frevert, Ernst U.,Camp, Heidi S.,Beutel, Bruce A.,Sham, Hing L.,Gu, Yu Gui
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p. 6078 - 6081
(2007/10/03)
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- Kumada coupling of aryl and vinyl tosylates under mild conditions
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Aryl and alkenyl tosylates are easily prepared, inexpensive and, thus, attractive for transition-metal-catalyzed couplings, but their reactivity is low. We report examples of mild, palladium-catalyzed coupling of aryl, alkenyl, and alkyl Grignard reagents with aryl and alkenyl tosylates. The resulting biaryls, vinylarenes, and alkylarenes were isolated in good to excellent yield. These couplings were conducted with a nearly equimolar ratio of the two reactants, and many examples were conducted at room temperature.
- Limmert, Michael E.,Roy, Amy H.,Hartwig, John F.
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p. 9364 - 9370
(2007/10/03)
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- Radical additions to tricarbonyl[(1-4-η)-2,methoxy-5- methylenecyclohexa- 1,3-diene]iron
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Tricarbonyl[(1-4-η)-2-methoxy-5-methylenecyclohexa-1,3-diene]iron was found to undergo facile radical addition regioselectively at the exocyclic methylene group to yield aromatized product upon demetalation. (C) 2000 Elsevier Science Ltd.
- Wei, Li Lan,Lai, Ming Chih,Ong, Chi Wi
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p. 3407 - 3410
(2007/10/03)
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