- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- Suzuki-Miyaura Cross-Coupling of Sulfoxides
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The utilization of diphenyl sulfoxides as versatile electrophilic coupling partners for the Suzuki-Miyaura reaction via C-S bond cleavage was successfully developed under palladium-N-heterocyclic carbene catalysis. The reactions showed good functional group compatibility, proceeded well under mild conditions, and provided biaryls in yields of up to 96%. A wide range of useful functional groups, such as fluoro, chloro, ether, hydroxyl, amide, cyano, keto, trimethylsilyl (TMS), and ester were tolerated under the reaction conditions; however, the use of phenylboronic anhydride and arylboronic acid pinacol esters generally would lead low yields. Good regioselectivity for the electron-poor phenyl group was achieved when unsymmetrical diphenyl sulfoxides were used. The protocol is applicable at the gram scale even with half the amount of catalyst. Density functional theory calculations were performed to investigate the reaction mechanism, indicating that the reaction occurred through oxidative addition, transmetalation, and reductive elimination to provide the final coupling product.
- Abduhulam, Hayrul,Cao, Changsheng,Chen, Qianwei,Dang, Yanfeng,Li, Chengxi,Shi, Yanhui,Wu, Shufeng,Yan, Shuqin
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p. 8168 - 8176
(2020/09/18)
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- C-F activation for C(sp2)-C(sp3) cross-coupling by a secondary phosphine oxide (SPO)-nickel complex
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A secondary phosphine oxide (SPO)-nickel catalyst allowed the activation of otherwise inert C-F bonds of unactivated arenes in terms of challenging couplings with primary and secondary alkyl Grignard reagents. The C-F activation is characterized by mild reaction conditions and high levels of branched selectivity. Electron-rich and electron-deficient arenes were suitable electrophiles for this transformation. In addition, this strategy also proved suitable to heterocycles and for the activation of C-O bonds under slightly modified conditions.
- Müller, Valentin,Ghorai, Debasish,Capdevila, Lorena,Messinis, Antonis M.,Ribas, Xavi,Ackermann, Lutz
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supporting information
p. 7034 - 7040
(2020/09/15)
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- Nickel-Catalyzed Csp2-Csp3 Bond Formation via C-F Bond Activation
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A nickel-catalyzed cross coupling of aryl fluorides via C-F bond activation has been developed. The alkylation method allows selective replacement of aryl fluorides by alkyl groups and enables the synthesis of diverse and otherwise difficult to access scaffolds in good yields.
- Ho, Yee Ann,Leiendecker, Matthias,Liu, Xiangqian,Wang, Chengming,Alandini, Nurtalya,Rueping, Magnus
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p. 5644 - 5647
(2018/09/12)
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- Alkylimidazole-Based Phosphines as Efficient Ligands for Palladium-Catalyzed Suzuki Reactions
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Two series of alkylimidazole-based phosphines were conveniently synthesized in one step from the corresponding alkylimidazole by selective deprotonation and quenching with chlorodiphenylphosphine. The novel ligands are easily tunable and exhibit good-to-excellent performance in the palladium-catalyzed Suzuki coupling reaction.
- Chen, Ting,Guan, Jin Tao,Zhang, Zhi Yong,Chen, Jing Jing,Liu, Fengyan,Liu, Xiaopei
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p. 551 - 555
(2017/12/26)
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- Nickel-Catalyzed C-O Bond-Cleaving Alkylation of Esters: Direct Replacement of the Ester Moiety by Functionalized Alkyl Chains
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Two efficient protocols for the nickel-catalyzed aryl-alkyl cross-coupling reactions using esters as coupling components have been established. The methods enable the selective oxidative addition of nickel to acyl C-O and aryl C-O bonds and allow the aryl-alkyl cross-coupling via decarbonylative bond cleavage or through cleavage of a C-O bond with high efficiency and good functional group compatibility. The protocols allow the streamlined, unconventional utilization of widespread ester groups and their precursors, carboxylic acids and phenols, in synthetic organic chemistry.
- Liu, Xiangqian,Jia, Jiaqi,Rueping, Magnus
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p. 4491 - 4496
(2017/07/24)
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- New low polar tolane cholesterics designed for infrared applications
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We have designed, synthesized and evaluated the physical properties of new fluorinated phenyltolane based chiral liquid crystal materials with 2-methylbutyl terminal chain. The 2- or 2,6-fluorosubstitution in combination with the phenyltolane core brings surprising improvement of mesomorphic properties. The investigated compounds are characterized by a broad temperature range of the cholesteric (chiral nematic N?) phase, very low melting temperatures and easy thermal control of selective reflection in the near infrared region. The moderate helical twisting power β, high optical anisotropy and source of a blue phase make these compounds attractive for cholesteric mixture formulations.
- Herman, Jakub,Kula, Przemys?aw
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p. 84231 - 84235
(2016/10/06)
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- Nickel-catalyzed alkylative cross-coupling of anisoles with grignard reagents via C-O bond activation
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We report nickel-catalyzed cross-coupling of methoxyarenes with alkylmagnesium halides, in which a methoxy group is eliminated. A wide range of alkyl groups, including those bearing β-hydrogens, can be introduced directly at the ipso position of anisole derivatives. We demonstrate that the robustness of a methoxy group allows this alkylation protocol to be used to synthesize elaborate molecules by combining it with traditional cross-coupling reactions or oxidative transformation. The success of this method is dependent on the use of alkylmagnesium iodides, but not chlorides or bromides, which highlights the importance of the halide used in developing catalytic reactions using Grignard reagents.
- Tobisu, Mamoru,Takahira, Tsuyoshi,Morioka, Toshifumi,Chatani, Naoto
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supporting information
p. 6711 - 6714
(2016/06/14)
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- Catalytic activity of 1-methylimidazole-based phosphine ligands in the palladium-catalyzed Suzuki coupling reaction
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The catalytic activities of three N-methylimidazole-based phosphine ligands in the Suzuki coupling reaction were tested using PdCl2 as the catalyst. The results showed all three phosphine ligands exhibited excellent activity towards the Suzuki reaction, and the catalytic activity decreased with increasing number of imidazole groups.
- Guan, Jin Tao,Song, Xiao Ming,Zhang, Zhi Yong,Wei, Ben Mei,Dai, Zhi Qun
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- The synthesis of chiral fluorinated 4-alkyl-4′-[(4-alkylphenyl) ethynyl]biphenyls
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We have designed, synthesized, and evaluated the physical properties of new fluorinated phenyltolane based chiral liquid crystal materials with 2-methylbutyl chains. This type of fluoro-substitution in chemical combination with a phenyltolane core brings a surprising improvement to the mesomorphic properties. The investigated compounds exhibit broad temperature ranges for the N* phase and very low melting points. All homologues exhibited Blue Phase. We have applied a Cu-catalyzed cross-coupling reaction between aryl Grignard reagents and alkyl bromides for the synthesis of the products.
- Herman, Jakub,Kula, Przemys?aw
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p. 3621 - 3623
(2013/07/05)
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- Proline catalyzes direct C-H arylations of unactivated arenes
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Several amino acids were tested to catalyze the transition-metal-free direct C-H arylation of unactivated benzene derivatives. Among them, proline was found to be an excellent catalyst for the cross-coupling between aryl halides and unactivated arenes. The reaction presumably involves an aryl radical anion as the intermediate based on several experiments. The reaction using this catalyst system offers an option toward establishing an environmentally benign and cost-effective route to biaryls.
- Tanimoro, Kouichi,Ueno, Minoru,Takeda, Kazutaka,Kirihata, Mitsunori,Tanimori, Shinji
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p. 7844 - 7849
(2013/01/15)
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- Novel and unexpected deamination during the palladium-catalysed cross- coupling of haloanilines and arylboronic acids
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Palladium-catalysed cross-coupling reactions involving haloanilines and arylboronic acids produce the expected biaryl products, but additionally a substantial quantity of the corresponding deaminated biaryl is also generated which constitutes a novel synthetic methodology.
- Hird, Michael,Seed, Alexander J.,Toyne, Kenneth J.
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p. 438 - 440
(2007/10/03)
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- Synthesis of Isocyano and (Haloalkynyl)Biphenyls: New Thermotropic Liquid Crystals
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4-n-Alkyl-4'-cyanobiphenyls (1) have achieved widespread application as stable thermotropic liquid crystals with mesophases at room temperature.The importance of the cyano group in the liquid-crystalline behaviour of these compounds is not clearly defined.By modifying this functional group with minimal changes in molecular geometry, we have found two new classes of mesomorphs, 4-n-Alkyl-4'-isocyanobiphenyls (2) and 4-n-alkyl-4'-(haloalkynyl)biphenyls (3).The synthesis of these compounds is described.Compound 2a (R = n-butyl) is non-mesomorphic, whereas compound 2b (R = n-pentyl) is a virtual liquid crystal melting at 34-5 deg C and supercooling to a nematic phase at 30 deg C, and 2c (R = n-hexyl) is a nematic liquid crystal from 9 to 19 deg C.Compounds of structure 3 (R = n-pentyl, X = Si(CH3)3, H, CH3, Cl) are not liquid crystals.The corresponding bromo- and iodoalkynes (3, R = n-pentyl, S = Br, I) are liquid crystals with mesomorphic ranges of 88-108 deg C and 110-119 deg C, respectively.
- Bailey, A. L.,Bates, Gordon S.
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p. 417 - 428
(2007/10/02)
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- SYNTHESIS OF 4-ALKYL-4'-CYANOBIPHENYLS
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Liquid crystals of the 4-alkyl-4'-cyanobiphenyl group were synthesized without the use of copper cyanide. 4-Alkyl-4'-formylbiphenyls and the 4-formyloximes of 4'-alkylbiphenyl, which possess a liquid-crystalline state, were isolated.Beginning with the pentyl homolog, they form an enantiotropic nematic phase, and beginning with octyl homolog they also form a smectic meso phase.
- Ruolene, Yu. I.,Adomenas, P. V.,Sirutkaitis, R. A.,Denis, G. I.
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p. 1187 - 1191
(2007/10/02)
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- NEW SIMPLE METHOD FOR OBTAINING 4-n-ALKYL-4 prime -CYANOBIPHENYLS.
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A new method is described of obtaining 4-n-alkyl-4 prime -cyanobiphenyls from biphenyl. First biphenyl is acrylated and the resulting ketone is reduced in conditions of the Huang-Minlon reaction; next the obtained 4-n-alkylbiphenyl is converted to 4-n-alkyl-4 prime -iodobiphenyl which readily reacts with copper cyanide giving the required nitrile with a good yield.
- Dabrowski,Witkiewicz,Kenig
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p. 251 - 259
(2007/10/02)
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