- Bulk TiPd alloys as easily recyclable and preactivation-free heterogeneous catalysts for cross-coupling reactions
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TiPd alloys have been found to be novel heterogeneous palladium catalysts for organic cross-coupling reactions. Catalyst preactivation is not necessary, resulting in facile recovery and reuse of the catalysts. Palladium is not leached into the reaction solution and the catalysts can be recycled several times without losing their catalytic activity.
- Azuma, Ryusei,Takahashi, Yuya,Kondo, Ryota,Suzuki, Takeyuki,Takeshita, Hiroyuki T.,Obora, Yasushi
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- [{Pd(μ-OH)Cl(IPr)}2]—A Highly Efficient Precatalyst for Suzuki–Miyaura Coupling also Able To Act under Base-Free Conditions
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[{Pd(μ-OH)Cl(IPr)}2] [IPr=N,N-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] was found to be a highly efficient precatalyst for Suzuki–Miyaura coupling that is able to act under base-free conditions.
- Ostrowska, Sylwia,Lorkowski, Jan,Kubicki, Maciej,Pietraszuk, Cezary
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- 4-Amino-1,2,4-triazoles-3-thiones and 1,3,4-oxadiazoles-2-thiones·palladium(II) recoverable complexes as catalysts in the sustainable Suzuki-Miyaura cross-coupling reaction
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The Suzuki-Miyaura cross-coupling reaction using 4-amino-1,2,4-triazoles and 1,3,4-oxadiazoles-2-thiones·palladium (II) is studied. The reaction is optimized and the most appropriate catalytic complex is tested with several aryl halides, boronic acids in an environmentally benign solvent system (H2O/EtOH). The recovery of the catalytic species is also surveyed because of the nature of the employed solvent. A domino process is efficiently carried out following the standard conditions. Several surface parameters of the ligands are analyzed and the resulting values are extrapolated to the insoluble palladium catalyst.
- Chehrouri, Manel,Moreno-Cabrerizo, Cristina,Othman, Adil A.,Chabour, Ihssene,Ferrándiz-Saperas, Marcos,Sempere, Inmaculada,D?nda?, H. Ali,de Gracia Retamosa,Sansano, José M.
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- Hypervalent iodine in synthesis XXXIII: Palladium-catalyzed cross- coupling reaction of potassium aryltrifluoroborates with diaryliodonium salts and hydroxy(tosyloxy)iodobenzene
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Potassium aryltrifluoroborates react smoothly with diaryliodonium salts and hydroxy(tosyloxy)iodobenzene, PhI(OH)OTs, under mild conditions in the presence of a palladium catalyst and without added base to afford biaryls in excellent yields.
- Xia, Min,Chen, Zhen-Chu
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- Catalytic C-H arylation of unactivated heteroaromatics with aryl halides by cobalt porphyrin
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Direct C-H arylation of unactivated heteroaromatics with aryl halides catalyzed by cobalt porphyrin is reported. The reaction is proposed to go through a homolytic aromatic substitution reaction. The aryl radical is electrophilic and a SOMO-HOMO interaction is predominant in the aryl radical addition process.
- Qian, Ying Ying,Wong, Ka Lai,Zhang, Meng Wen,Kwok, Tsz Yiu,To, Ching Tat,Chan, Kin Shing
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- Synthesis and characterization of palladium nanoparticles immobilized on graphene oxide functionalized with triethylenetetramine or 2,6-diaminopyridine and application for the Suzuki cross-coupling reaction
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Graphene oxide (GO) was functionalized with two organic ligands, triethylenetetramine (TETA) or 2,6-diaminopyridine (DAP), followed by palladium nanoparticles (Pd NPs) for the synthesis of Pd NPs/GO-TETA and Pd NPs/GO-DAP nanocomposites, respectively. The two heterogeneous nanocomposites were fully characterized and their efficiency was investigated for C[sbnd]C bond formation for the synthesis of biaryl compounds via the Suzuki cross-coupling reaction of aryl halides with arylboronic acid derivatives. The obtained results indicated that the Pd NPs/GO-TETA nanocomposite was more effective in the Suzuki coupling reaction as compared to Pd NPs/GO-DAP. Thus, the Suzuki cross-coupling reaction of different aryl halides with arylboronic acid derivatives using Pd NPs/GO-TETA nanocomposite catalyst in the presence of Na2CO3 as base in DMF/H2O (1/1) as solvent at 90 °C was carried out to afford the desired biaryl compounds in high to excellent yields (81–100%) and short reaction times (10–90 min). Additionally, Pd NPs/GO-TETA nanocomposite can be recovered and reused for 8 consecutive runs without any apparent loss of its catalytic activity, proving its high stability and potential use in organic transformations.
- Mirza-Aghayan, Maryam,Mohammadi, Marzieh,Boukherroub, Rabah
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- Suzuki-Miyaura Cross-Coupling Reaction with Potassium Aryltrifluoroborate in Pure Water Using Recyclable Nanoparticle Catalyst
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This paper describes the Suzuki Miyaura cross-coupling reaction of aryl bromides with potassium aryltrifluoroborates in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PSPdONPs). The reaction of aryl bromides having electron-withdrawing groups or electron-donating groups took place smoothly to give the corresponding coupling product in high yields. The catalyst recycles five times without significant loss of catalytic activity although a little bit increase in size of PdNPs was observed after the reaction.
- Kawase, Misa,Matsuoka, Kyosuke,Shinagawa, Tsutomu,Hamasaka, Go,Uozumi, Yasuhiro,Shimomura, Osamu,Ohtaka, Atsushi
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- Pyrazole-Mediated C-H Functionalization of Arene and Heteroarenes for Aryl-(Hetero)aryl Cross-Coupling Reactions
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Herein we introduce a transition-metal-free protocol that involves a commercially available, inexpensive pyrazole molecule to conduct C-C cross-coupling reactions at room temperature via a radical pathway. Using this method, an aryldiazonium salt has been coupled to a wide range of arenes and heteroarenes including benzene, mesitylene, thiophene, furan, benzoxazole to result the corresponding biaryl products. The full reaction mechanism is elucidated along with the crystallographic probation of an active initiator species. A potassium-stabilized deprotonated pyrazole steers single-electron transfer to the substrate and behaves as an initiator for the reaction.
- Kundu, Abhishek,Dey, Dhananjay,Pal, Subhankar,Adhikari, Debashis
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p. 15665 - 15673
(2021/11/16)
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- One-step synthesis of magnetically recyclable palladium loaded magnesium ferrite nanoparticles: application in synthesis of anticancer drug PCI-32765
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Novel Palladium nanoparticles supported nano Magnesium ferrite catalyst (Pd/MgFe2O4) was synthesized by one-step ultrasound assisted coprecipitation. In-situ formed by-products assisted salt cage calcination approach was employed to
- Dasari, Gopala Krishna,Sunkara, Satyaveni,Gadupudi, Purna Chandra Rao
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p. 753 - 763
(2020/02/13)
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- A facile synthesis of mesoporous graphitic carbon nitride supported palladium nanoparticles as highly effective and reusable catalysts for Stille coupling reactions under mild conditions
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The development of a Stille coupling protocol that is operable under moderate conditions without using a base is highly required for the synthetic organic chemistry community, which requires an efficient nanocatalyst. In this respect, addressed herein is a facile one-pot synthesis of mesoporous graphitic carbon nitride (mpg-CN) supported Pd NPs, denoted as mpg-CN/Pd hereafter, and investigation of their catalytic activity in Stille cross-coupling reactions for the first time. It has been demonstrated that mpg-CN nanosheets can serve as not only a support material but also a stabilizer for the generation of 4.5 nm Pd NPs. The ecofriendly generated heterogeneous nanocatalyst was characterized by TEM, XRD, XPS, BET surface area and ICP-MS analysis. The mpg-CN/Pd nanocatalysts showed high activity in the Stille coupling reaction of a variety of electron-deficient and electron-rich aryl iodides/bromides and two different organostannanes with a wide substrate scope to afford the corresponding biaryls without using any bases and additional ligands under relatively mild conditions. The catalyst can be easily recovered from the reaction medium by centrifugation. It can be reused at least 5 times without any loss of activity.
- Cetin, Sultan,Kalay, Erbay,Kolemen, Safacan,Metin, ?nder
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p. 6714 - 6723
(2020/05/16)
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- Transition-Metal-Free Synthesis of Heterobiaryls through 1,2-Migration of Boronate Complex
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The synthesis of a diverse range of heterobiaryls has been achieved by a transition-metal-free sp2–sp2 cross-coupling strategy using lithiated heterocycle, aryl or heteroaryl boronic ester and an electrophilic halogen source. The construction of heterobiaryls was carried out through electrophilic activation of the aryl–heteroaryl boronate complex, which triggered 1,2-migration from boron to the carbon atom. Subsequent oxidation of the intermediate boronic ester afforded heterobiaryls in good yield. A comprehensive 11B NMR study has been conducted to support the mechanism. The cross coupling between two nucleophilic cross coupling partners without transition metals reveals a reliable manifold to procure heterobiaryls in good yields. Various heterocycles like furan, thiophene, benzofuran, benzothiophene, and indole are well tolerated. Finally, we have successfully demonstrated the gram scale synthesis of the intermediates for an anticancer drug and OLED material using our methodology.
- Paul, Swagata,Das, Kanak Kanti,Manna, Samir,Panda, Santanu
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supporting information
p. 1922 - 1927
(2020/02/04)
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- Direct suzuki-miyaura coupling with naphthalene-1,8-diaminato (dan)-substituted organoborons
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The actually direct Suzuki-Miyaura coupling with "protected" R-B(dan) (dan = naphthalene-1,8-diaminato) was demonstrated to smoothly occur without in situ deprotection of the B(dan) moiety. The use of t-BuOK (Ba(OH)2 in some cases) as a base under anhydrous conditions is the key to the successful cross-coupling, where R-B(dan) is readily converted into a transmetalation-active borate-form, regardless of the well-accepted diminished boron-Lewis acidity.
- Yoshida, Hiroto,Seki, Michinari,Kamio, Shintaro,Tanaka, Hideya,Izumi, Yuki,Li, Jialun,Osaka, Itaru,Abe, Manabu,Andoh, Hiroki,Yajima, Tomoki,Tani, Tomohiro,Tsuchimoto, Teruhisa
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p. 346 - 351
(2019/12/24)
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- Black phosphorus as a metal-free, visible-light-active heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes
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Black phosphorus (BP) is for the first time employed as a metal-free, heterogeneous photoredox catalyst for the direct C-H arylation of heteroarenes with aryl diazonium salts. The arylated heteroarenes are obtained in moderate to good yields under visible-light illumination, and the protocol is shown to be applicable for the scale-up synthesis.
- Kalay, Erbay,Kü?ükke?eci, Hüseyin,Kilic, Haydar,Metin, ?nder
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supporting information
p. 5901 - 5904
(2020/06/04)
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- A photocatalytic ensemble HP-T?Au-Fe3O4: Synergistic and balanced operation in Kumada and Heck coupling reactions
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A supramolecular catalytic ensemble HP-T?Au-Fe3O4 supported by highly branched assemblies of hexaphenylbenzene (HPB) derivatives has been developed. The as-prepared HP-T?Au-Fe3O4 nanohybrid material serves as an efficient catalytic system to prepare biaryl derivatives through the Kumada cross-coupling reaction using aryl chlorides as one of the coupling partners under mild reaction conditions (visible light irradiation, aqueous media, aerial conditions, short reaction time). Through the cooperative effect of Au NPs and Fe3O4 NPs, dual activation of aryl chlorides for the generation of aryl radical intermediates is achieved. On the other hand, oligomeric assemblies contributed significantly to the enhancement of the reaction rate and yield of the product by facilitating the reductive elimination step. Different mechanistic studies confirm the involvement of Au NPs, Fe3O4 NPs and oligomeric assemblies in the synergistic and balanced operation of HP-T?Au-Fe3O4 nanohybrid materials in the efficient completion of the catalytic cycle of the Kumada coupling reaction. Being magnetic, the catalytic ensemble could be recycled for up to five catalytic cycles. The as-prepared supramolecular photocatalytic ensemble also works efficiently in Heck coupling reactions involving aryl chlorides and aryl iodides as the coupling partner.
- Bhalla, Vandana,Kaur, Harpreet,Kumar, Manoj
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supporting information
p. 8036 - 8045
(2020/11/30)
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- 1-Aryltriazenes in the Suzuki, Heck, and Sonogashira Reactions in Imidazolium-ILs, with [BMIM(SO3H)][OTf] or Sc(OTf)3 as Promoter, and Pd(OAc)2 or NiCl2·glyme as Catalyst
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1-Aryltriazenes, the protected and more stable form of aryl-diazonium species, can be conveniently unmasked with Br?nsted acidic-IL or Sc(OTf)3 and coupled with a host of aryl/heteroaryl boronic acids, styrenes, and aryl/alkyl acetylenes in the Suzuki, Heck and Sonogashira reactions in one-pot and in respectable isolated yields, by using palladium or nickel catalyst in readily available imidazolium ILs as solvent, under mild conditions. The scope of these reactions are explored, and the potential for recovery/reuse of the IL solvent is also addressed.
- Sutar, Suraj M.,Savanur, Hemantkumar M.,Malunavar, Shruti S.,Prabhala, Pavankumar,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information
p. 6088 - 6093
(2019/09/17)
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- A highly efficient and recyclable NiCl2(dppp)/PEG-400 system for Suzuki-Miyaura reaction of aryl chlorides with arylboronic acids
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NiCl2(dppp) in PEG-400 is shown to be a highly efficient catalyst for Suzuki-Miyaura coupling of aryl chlorides with arylboronic acids. The reaction could be conducted at 100 °C using K3PO4 as base, yielding a variety of biaryls in good to excellent yields. The isolation of the products was readily performed by extraction with petroleum ether and NiCl2(dppp)/PEG-400 system could be easily recycled and reused up to five times without significant loss of activity. Our system not only avoids the use of easily volatile and toxic dioxane or toluene as a solvent but also solves the basic problem of nickel catalyst reuse.
- Liao, Yang,Yang, Weisen,Wei, Ting,Cai, Mingzhong
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supporting information
p. 1134 - 1142
(2019/04/10)
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- Palladium nanoparticles immobilized on the magnetic few layer graphene support as a highly efficient catalyst for ligand free Suzuki cross coupling and homo coupling reactions
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In this study, we prepared a magnetic metal–graphene nanocomposite for the synthesis of substituted biaryls via Suzuki cross coupling and homo coupling reaction of aryl halides. The magnetic few layer graphene composite was synthesized by using one-step electrochemical exfoliation of graphite foil in aqueous iron (II) ammonium sulfate as electrolyte without using of any additive or corrosive media. Then, Fe2O3@FLG composite was used an efficient support for the immobilization and suitable dispersing of palladium nanoparticles. The obtained Fe2O3@FLG@Pd0 nanocomposite was characterized using FT-IR, SEM, TEM, EDS, XRD, VSM and ICP-AES analysis. Very low loading of this catalyst was displayed high activity in the producing substituted biaryls. It simply recovered from the reaction mixture and reused without any pre-activation in six consecutive runs with no loss of its catalytic activity or the observation of any detectable palladium leaching process.
- Rafiee, Fatemeh,Khavari, Parvaneh,Payami, Zahra,Ansari, Narges
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- N,S-chelating triazole-thioether ligand for highly efficient palladium-catalyzed Suzuki reaction
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1,2,3-Triazole-thioether compounds could serve as efficient ligands for Pd-catalyzed Suzuki reactions of various aryl iodides, bromides and chlorides. The reactions feature wide substrate scope and mild reaction conditions. Besides, shorter reaction time, lower catalyst loadings and quantitative yields with a turnover-frequency (TOF) value of up to 11,880 h?1 are other advantageous of this attractive protocol. The crystal structure analyses and computational studies revealed that the higher catalytic activity of the corresponding chelated palladium complex ascribed to the lower energy gap and the lower redox potential.
- Yan, Qiong,Zheng, Lei,Li, Miaomiao,Chen, Yunfeng
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p. 101 - 105
(2019/07/19)
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- Anthranilamide (aam)-substituted arylboranes in direct carbon-carbon bond-forming reactions
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Anthranilamide (aam)-substituted arylboranes, which were reported to serve as masked boranes in the Suzuki-Miyaura coupling, have been found to be directly cross-coupled just by use of an aqueous medium. The excellent stability of 2-pyridyl-B(aam) toward protodeborylation allowed their smooth cross-coupling.
- Kamio, Shintaro,Kageyuki, Ikuo,Osaka, Itaru,Yoshida, Hiroto
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supporting information
p. 2624 - 2627
(2019/03/05)
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- C–H Arylation of N-Heteroarenes under Metal-Free Conditions and its Application towards the Synthesis of Pentabromo- and Pentachloropseudilins
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Herein, we are reporting metal-free conditions for radical initiation and direct C–H arylation of N-heteroarenes. Starting from aniline, the corresponding arenediazonium salt generated in situ is reduced to an aryl radical in the presence of chloropromazine hydrochloride, a new reagent for this application. The optimized procedures are mild, operationally simple, and are working successfully with more diverse substrates in comparison to reported methods. The optimized method is also employed for the synthesis of marine natural products Pentabromo- and Pentachloropseudilins (PBP/PCP). In the present study, we also validated the potential of the Pentachloropseudilin (PCP), thus synthesized, for inhibition of Myosin1 function in mammalian cells and confirmed that PCP phenocopies Myosin1c depletion in cells.
- Kumar, Mukesh,Sharma, Shweta,Sil, Parijat,Kushwaha, Manoj,Mayor, Satyajit,Vishwakarma, Ram A.,Singh, Parvinder Pal
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supporting information
p. 3591 - 3598
(2019/06/20)
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- Perylenequinonoid-catalyzed photoredox activation for the direct arylation of (het)arenes with sunlight
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Naturally occurring perylenequinonoid pigments (PQPs) have attracted considerable attention owing to their excellent properties of photosensitization. They have been widely investigated as an aspect of photophysics and photobiology. However, their applications in photocatalysis are yet to be explored. We report here that sunlight along with 1 mol% cercosporin, which is one of the perylenequinonoid pigments, catalyzes the direct C-H bond arylation of (het)arenes by a photoredox process with good regioselectivity and broad functional group compatibility. Furthermore, a gram-scale reaction with great conversions of substrates was achieved even by a cercosporin-containing supernatant without organic solvent extraction and purification after liquid fermentation. Thus we set up a bridge between microbial fermentation and organic photocatalysis for chemical reactions in a sustainable, environmentally friendly manner.
- Zhang, Shiwei,Tang, Zhaocheng,Bao, Wenhao,Li, Jia,Guo, Baodang,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 4364 - 4369
(2019/05/10)
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- PEPPSI-type palladium 1,2,3-triazolin-5-ylidene complexes – Synthesis, structure and catalytic properties in Suzuki-Miyaura coupling
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Palladium complexes of the general formula [PdCl2(tzNHC)(pyridine)] bearing a series 1,2,3-triazolin-5-ylidene (tzNHC) ligands were synthesized and characterized by spectroscopic methods and X-ray analysis. Complexes exhibit catalytic activity in the Suzuki-Miyaura coupling of boronic acids with aryl bromides.
- Ostrowska, Sylwia,Kubicki, Maciej,Pietraszuk, Cezary
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supporting information
p. 317 - 323
(2018/06/29)
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- Mechanochemical Activation of Zinc and Application to Negishi Cross-Coupling
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A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross-coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp3)–C(sp2) and C(sp2)–C(sp2) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.
- Cao, Qun,Howard, Joseph L.,Wheatley, Emilie,Browne, Duncan L.
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supporting information
p. 11339 - 11343
(2018/08/28)
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- Accessing Heterobiaryls through Transition-Metal-Free C-H Functionalization
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Herein we report a transition-metal-free synthetic protocol for heterobiaryls, one of the most important pharmacophores in the modern drug industry, employing a new multidonor phenalenyl (PLY)-based ligand. The current procedure offers a wide substrate scope (24 examples) with a low catalyst loading resulting in an excellent product yield (up to 95%). The reaction mechanism involves a single electron transfer (SET) from a phenalenyl-based radical to generate a reactive heteroaryl radical. To establish the mechanism, we have isolated the catalytically active SET initiator, characterizing by a magnetic study.
- Banik, Ananya,Paira, Rupankar,Shaw, Bikash Kumar,Vijaykumar, Gonela,Mandal, Swadhin K.
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p. 3236 - 3244
(2018/03/23)
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- Synthesis of bench-stable solid triorganoindium reagents and reactivity in palladium-catalyzed cross-coupling reactions
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Bench-stable solid triorganoindium compounds have been prepared by coordination with 4-(dimethylamino)pyridine (DMAP). The solid R3In(DMAP) complexes are obtained from the corresponding solution of R3In in quantitative yield and can
- Gil-Negrete, José M.,Pérez Sestelo, José,Sarandeses, Luis A.
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supporting information
p. 1453 - 1456
(2018/02/19)
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- Stannylation of Aryl Halides, Stille Cross-Coupling, and One-Pot, Two-Step Stannylation/Stille Cross-Coupling Reactions under Solvent-Free Conditions
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Solvent-free protocols for palladium-catalyzed stannylation of aryl halides, Stille cross-coupling, and one-pot, two-step stannylation/Stille cross-coupling (SSC) are reported for the first time. (Het)aryl halides bearing acceptor, donor, as well as sterically demanding substituents are stannylated and/or coupled in high yields. The reactions are catalyzed by conventional palladium(II) acetate/PCy3 [Pd(OAc)2/PCy3] under air, using available base CsF, and without the use of high purity reagents. The developed synthetic procedures are versatile, robust, and easily scalable. The absence of solvent, and the elimination of isolation procedures of aryl stannanes makes the SSC protocol simple, step economical, and highly efficient for the synthesis of biaryls in a one-pot two-step procedure.
- Gribanov, Pavel S.,Golenko, Yulia D.,Topchiy, Maxim A.,Minaeva, Lidiya I.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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p. 120 - 125
(2018/01/17)
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- Cyrene as a Bio-Based Solvent for the Suzuki-Miyaura Cross-Coupling
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The Suzuki-Miyaura (SM) cross-coupling is the most broadly utilized Pd-catalyzed C-C bond-forming reaction in the chemical industry. A large proportion of SM couplings employ dipolar aprotic solvents; however, current sustainability initiatives and increasingly stringent regulations advocate the use of alternatives that exhibit more desirable properties. Here we describe the scope and utility of the bio-derived solvent Cyrene in SM cross-couplings and evaluate its suitability as a reaction medium for this benchmark transformation from discovery to gram scale.
- Wilson, Kirsty L.,Murray, Jane,Jamieson, Craig,Watson, Allan J. B.
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supporting information
p. 650 - 654
(2017/12/26)
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- Non-Directed Cross-Dehydrogenative (Hetero)arylation of Allylic C(sp3)?H bonds enabled by C?H Activation
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Herein, we report the selective, non-directed and cross-dehydrogenative coupling of allylic C(sp3)?H bonds with C(sp2)?H bonds of (hetero)arenes. The methodology employs olefins and (hetero)arenes which are abundantly available chemical feedstocks, and could be applied in late-stage functionalization reactions of pharmaceuticals. Furthermore, the system exclusively delivers the allylic C?C coupling products highlighting the preservation of the olefin substitution pattern for further derivatization.
- Lerchen, Andreas,Knecht, Tobias,Koy, Maximilian,Ernst, Johannes B.,Bergander, Klaus,Daniliuc, Constantin G.,Glorius, Frank
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supporting information
p. 15248 - 15252
(2018/10/20)
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- Photo-oxidative Cross-Dehydrogenative Coupling-Type Reaction of Thiophenes with α-Position of Carbonyls Using a Catalytic Amount of Molecular Iodine
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A metal-free photo-oxidative intermolecular C-H/C-H coupling reaction of thiophenes is demonstrated with carbonyls using a catalytic amount of molecular iodine. In this system, molecular oxygen in the air acted as a terminal oxidant to regenerate molecular iodine. A mechanistic study was also performed.
- Sudo, Yusuke,Yamaguchi, Eiji,Itoh, Akichika
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supporting information
p. 1610 - 1613
(2017/04/13)
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- Gram-scale synthesis of aligned C3N4-polypyrrole heterojunction aerogels with tunable band structures as efficient visible and near infrared light-driven metal-free photocatalysts
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The assembly of aligned porous materials from simple building blocks is of widespread interest for engineering materials with enhanced and synergistic properties. To date, however, how to develop 3D heterojunction aerogels with aligned porosity based on 2D semiconductor materials and 1D conducting polymers for solar energy conversion in the visible and near-infrared (NIR) light region remains a significant challenge. Here a new class of gram-scale 3D aligned heterojunction aerogels of polypyrrole (PPy)/C3N4 nanosheets (NSs) were designed and synthesized by directional freezing of polypyrrole (PPy)/polyvinyl alcohol (PVA) and C3N4 NS aqueous suspension. The synthesis of aligned C3N4-PPy heterojunction aerogels can be achieved on a large scale. The formed aerogel expresses stable and uniform dispersion of the two building blocks, long-range channel aligned structures along the whole monolithic sample, and additional special complementary optical properties between PPy and C3N4 NSs. Based on the above unique structure and optical properties, this novel metal-free heterojunction aerogel exhibits excellent photocatalytic activity and long-term stability for direct arylation of heteroaromatics under visible and near infrared (NIR) light irradiation at room temperature, far exceeding those of the single- and two-component systems. Our work therefore not only provides a new approach to obtain aligned heterojunction aerogels based on metal free semiconductors but also paves a way to develop gram-scale aerogels as a new type of highly efficient visible and NIR light induced heterogeneous photocatalyst.
- Liu, Jian,Wang, Hao,Bai, Jinwei,Li, Tianrong,Yang, Yanmei,Peng, Yong,Wang, Baodui
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p. 24920 - 24928
(2017/12/15)
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- A phosphine-free, atom-efficient cross-coupling of aryl iodides with triarylindiums or trialkynylindiums catalyzed by immobilization of palladium(0) in MCM-41
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The first phosphine-free heterogeneous atom-efficient cross-coupling reaction of aryl iodides with triarylindiums or trialkynylindiums was achieved in THF at 68 °C by using 1 mol% of MCM-41-immobilized palladium(0)-Schiff base complex [MCM-41-N,N-Pd(0)] as catalyst, yielding a variety of unsymmetrical biaryls and arylalkynes in good to excellent yields. The heterogeneous palladium(0) catalyst could easily be prepared via a simple procedure from commercially readily available reagents, and recovered by filtration of the reaction solution and recycled at least 10 times without significant loss of activity.
- Lei, Zhiwei,Liu, Haiyi,Cai, Mingzhong
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- Method for cleaving alpha carbon-carbon single bonds in ketone under condition of metal-free catalysis
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The invention discloses a method for selectively activating and cleaving alpha carbon-carbon single bonds in ketone under the condition of metal-free catalysis. The method is characterized in that the alpha carbon-carbon single bonds in the ketone are activated and cleaved by solvent induction and driving of intermediate structure factors formed by the ketone and hydrazine without metal catalysts. Transition metal for catalysis is omitted, the method is environmentally friendly, reaction cost is reduced to a certain degree, methodology of selective cleavage of the carbon-carbon single bonds is enriched, and a new idea is provided for activation of inertial chemical bonds under mild conditions.
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Paragraph 0017; 0026
(2017/10/07)
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- Highly efficient palladium(II) hydrazone based catalysts for the Suzuki coupling reaction in aqueous medium
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Synthesis of a new family of air stable palladium(ii)benzhydrazone complexes of the general formula [PdCl(PPh3)(L)] (where HL = thiophene aldehyde benzhydrazones) incorporating PPh3 and chloride as co-ligands has been described through a single and convenient step with good yields. All the new complexes have been fully characterized by means of elemental analysis, IR, UV-vis, and NMR spectral methods. The molecular structures of three of the complexes were determined by single crystal X-ray crystallography, which confirm the coordination mode of benzhydrazone and reveal the presence of a distorted square planar geometry around the Pd ion. The complexes 1-5 (0.05 mol%) have been found to be a highly active catalytic system in the mono and double Suzuki-Miyaura cross coupling reaction of deactivated aryl and heteroaryl bromides with different types of aryl boronic acids in neat water and the maximum yield was up to >99%. Notably, these catalysts work well with ultra-low loading of the catalysts and show high turnover numbers in a short time towards different substrates. Moreover, the catalysts could be simply recovered and reused five times without significant loss of efficiency.
- Muthumari, Subramanian,Ramesh, Rengan
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p. 52101 - 52112
(2016/06/13)
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- Biarylalkyl Carboxylic Acid Derivatives as Novel Antischistosomal Agents
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Parasitic platyhelminths are responsible for serious infectious diseases, such as schistosomiasis, which affect humans as well as animals across vast regions of the world. The drug arsenal available for the treatment of these diseases is limited; for example, praziquantel is the only drug currently used to treat ≥240 million people each year infected with Schistosoma spp., and there is justified concern about the emergence of drug resistance. In this study, we screened biarylalkyl carboxylic acid derivatives for their antischistosomal activity against S. mansoni. These compounds showed significant influence on egg production, pairing stability, and vitality. Tegumental lesions or gut dilatation was also observed. Substitution of the terminal phenyl residue in the biaryl scaffold with a 3-hydroxy moiety and derivatization of the terminal carboxylic acid scaffold with carboxamides yielded compounds that displayed significant antischistosomal activity at concentrations as low as 10 μm with satisfying cytotoxicity values. The present study provides detailed insight into the structure–activity relationships of biarylalkyl carboxylic acid derivatives and thereby paves the way for a new drug-hit moiety for fighting schistosomiasis.
- M?der, Patrick,Blohm, Ariane S.,Quack, Thomas,Lange-Grünweller, Kerstin,Grünweller, Arnold,Hartmann, Roland K.,Grevelding, Christoph G.,Schlitzer, Martin
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supporting information
p. 1459 - 1468
(2016/07/16)
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- A atom-efficient cross-coupling reaction of aryl iodides with triarylbismuths catalyzed by immobilization of palladium(II)-Schiff base complex in MCM-41
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The first phosphine-free heterogeneous atom-efficient cross-coupling of aryl iodides with triarylbismuths was achieved in NMP using K2CO3 as base at 110 °C in the presence of 2 mol % of an MCM-41-immobilized palladium(II)-Schiff base complex [MCM-41-N,N-Pd(OAc)2], yielding a variety of unsymmetrical biaryls in good to excellent yields. This new heterogeneous palladium catalyst exhibits high catalytic activity and can be recovered by a simple filtration of the reaction solution and recycled for at least 10 consecutive trials without any decreases in activity. Our system not only avoids the use of phosphine ligands, but also solves the basic problem of palladium catalyst recovery and reuse.
- Xu, Caifeng,Yin, Lin,Huang, Bin,Liu, Haiyi,Cai, Mingzhong
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p. 2065 - 2071
(2016/04/09)
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- Kinetic Studies on the Palladium(II)-Catalyzed Oxidative Cross-Coupling of Thiophenes with Arylboron Compounds and Their Mechanistic Implications
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Reaction orders for the key components in the palladium(II)-catalyzed oxidative cross-coupling between phenylboronic acid and ethyl thiophen-3-yl acetate were obtained by the method of initial rates. It turned out that the reaction rate not only depended on the concentration of palladium trifluoroacetate (reaction order: 0.97) and phenylboronic acid (reaction order: 1.26), but also on the concentration of the thiophene (reaction order: 0.55) and silver oxide (reaction order: -1.27). NMR spectroscopy titration studies established the existence of 1:1 complexes between the silver salt and both phenylboronic acid and ethyl thiophen-3-yl acetate. A low inverse kinetic isotope effect (kH/kD=0.93) was determined upon employing the 4-deuterated isotopomer of ethyl thiophen-3-yl acetate and monitoring its reaction to the 4-phenyl-substituted product. A Hammett analysis performed with para-substituted 2-phenylthiophenes gave a negative ρ value for oxidative cross-coupling with phenylboronic acid. Based on the kinetic data and additional evidence, a mechanism is suggested that invokes transfer of the phenyl group from phenylboronic acid to a 1:1 complex of palladium trifluoroacetate and thiophene as the rate-determining step. Proposals for the structure of relevant intermediates are made and discussed.
- Schnapperelle, Ingo,Breitenlechner, Stefan,Bach, Thorsten
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supporting information
p. 18407 - 18416
(2015/12/24)
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- METHOD FOR PRODUCING AROMATIC COMPOUND
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A method is provided for producing an aromatic compound, including a step of mixing a compound represented by formula (A) and a compound represented by formula (B): in the presence of at least one phosphine compound selected from the group consisting of a phosphine represented by formula (C) and a phosphonium salt represented by formula (F): a base, a palladium compound, and an aprotic organic solvent.
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Paragraph 0520
(2015/11/30)
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- An efficient palladium N-heterocyclic carbene catalyst allowing the suzuki-miyaura cross-coupling of aryl chlorides and arylboronic acids at room temperature in aqueous solution
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The application of a highly active Pd-NHC catalyst for the Suzuki-Miyaura cross-coupling of a broad variety of electronically activated and deactivated aryl chlorides with different arylboronic acids in excellent yields is described. This catalyst can be handled under aerobic conditions, is active with low catalyst loadings at room temperature and in an aqueous reaction medium and allows the application of cheap potassium carbonate as the base.
- Rajabi, Fatemeh,Thiel, Werner R.
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p. 1873 - 1877
(2014/06/09)
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- Direct C-H arylation of thiophenes at low catalyst loading of a phosphine-free bis(alkoxo)palladium complex
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An efficient phosphine-free direct C-H arylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1-0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or electron-withdrawing groups. The reactivities of the 2- and 5-positions of thiophenes are equivalent and not dependent on steric hindrance under optimal conditions. This condition can also be applied to other heterocyclic moieties such as benzothiophene, benzofuran, and pyrrole with high conversion yields.
- Li, Yabo,Wang, Jingran,Huang, Mengmeng,Wang, Zhiwei,Wu, Yusheng,Wu, Yangjie
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p. 2890 - 2897
(2014/05/06)
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- Palladium-Catalysed Direct Cross-Coupling of Organolithium Reagents with Aryl and Vinyl Triflates
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A palladium-catalysed cross-coupling of organolithium reagents with aryl and vinyl triflates is presented. The reaction proceeds at 50 or 70 C with short reaction times, and the corresponding products are obtained with moderate to high yields, with a variety of alkyl and (hetero)aryl lithium reagents.
- Vila, Carlos,Hornillos, Valentín,Giannerini, Massimo,Fa?anás-Mastral, Martín,Feringa, Ben L.
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supporting information
p. 13078 - 13083
(2016/02/19)
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- Trisulfur radical anion as the key intermediate for the synthesis of thiophene via the interaction between elemental sulfur and NaO t Bu
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A facile base-promoted sulfur-centered radical generation mode and a single-step protocol for the synthesis of thiophene derivatives using 1,3-diynes via the interaction between elemental sulfur and NaOtBu has been reported. EPR experiments revealed that the trisulfur radical anion acts as a key intermediate of this process. A plausible mechanism has been proposed.
- Zhang, Guoting,Yi, Hong,Chen, Hong,Bian, Changliang,Liu, Chao,Lei, Aiwen
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p. 6156 - 6159
(2015/01/16)
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- Flexible routes to thiophenes
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Three convergent routes to thiophenes are described, hinging on the radical addition of α-xanthyl ketones to ethyl vinyl sulfide or to vinyl pivalate. The latter route ultimately proved to be the most versatile and efficient (61-94%).
- Jullien, Helene,Quiclet-Sire, Beatrice,Tetart, Thomas,Zard, Samir Z.
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supporting information
p. 302 - 305
(2014/01/23)
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- Synthesis of heteroaryl compounds through cross-coupling reaction of aryl bromides or benzyl halides with thienyl and pyridyl aluminum reagents
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An efficient method for synthesis of useful biaryl building blocks containing 2-thienyl, 3-thienyl, 2-pyridyl, and 3-pyridyl moieties was provided through cross-coupling reactions of aryl bromides or benzyl halides with heteroaryl aluminum reagents in the presence of Pd(OAc)2 and (o-tolyl)3P. The coupling reaction also worked efficiently with heteroaryl bromides affording series of heterobiaryl compounds. The reaction of phenylbromide with in situ prepared 3-pyridyl aluminum was demonstrated to afford the product 8a in high yield. Additionally, the catalytic system was also suited well for the coupling reaction of benzyl halides with pyridyl aluminum reagents to afford series of pyridyl-arylmethane.
- Chen, Xu,Zhou, Lingmin,Li, Yimei,Xie, Tao,Zhou, Shuangliu
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p. 230 - 239
(2014/01/17)
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- Expanded ring diaminocarbene palladium complexes: Synthesis, structure, and Suzuki-Miyaura cross-coupling of heteroaryl chlorides in water
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A series of new 6- and 7-membered N-heterocyclic carbene (NHC) complexes of palladium (NHC)Pd(cinn)Cl (cinn = cinnamyl = 3-phenylallyl) were synthesized and characterized structurally in the solid state. The influence of ring size (5, 6 or 7) and bulkiness of N-aryl substituents (Mes = 2,4,6-trimethylphenyl, or Dipp = 2,6-diisopropylphenyl) in carbenes on palladium catalysed Suzuki-Miyaura cross-coupling was revealed. Due to the unique stereoelectronic properties of expanded ring NHCs, a versatile, highly efficient green protocol of coupling of heteroaromatic chlorides and bromides with boronic acids has been developed. High quantitative yields of biaryls were achieved with water as solvent, under air, using low catalyst and phase transfer agent loadings, and with mild and environmentally benign base NaHCO3. The Royal Society of Chemistry 2013.
- Kolychev, Eugene L.,Asachenko, Andrey F.,Dzhevakov, Pavel B.,Bush, Alexander A.,Shuntikov, Viacheslav V.,Khrustalev, Victor N.,Nechaev, Mikhail S.
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p. 6859 - 6866
(2013/08/25)
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- Suzuki-miyaura cross-coupling under solvent-free conditions
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A solvent-free reaction protocol for Suzuki-Miyaura cross-couplings was developed. (Hetero)aryl bromides and chlorides are coupled with pinacol arylboronates in high yields. The reaction is catalyzed by conventional bis(triphenylphosphine)palladium(II) chloride [(PPh3) 2PdCl2] and/or palladium(II) acetate/SPhos [Pd(OAc) 2/SPhos] under air. Copyright
- Asachenko, Andrey F.,Sorochkina, Kristina R.,Dzhevakov, Pavel B.,Topchiy, Maxim A.,Nechaev, Mikhail S.
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p. 3553 - 3557
(2014/01/06)
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- Iodo-Bodipys as visible-light-absorbing dual-functional photoredox catalysts for preparation of highly functionalized organic compounds by formation of C-C bonds via reductive and oxidative quenching catalytic mechanisms
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Iodo-Bodipys were used as organic catalysts for three different photoredox catalytic organic reactions, i.e. the aza-Henry reaction of tetrahydroisoquinoline, oxidation/[3 + 2] cycloaddition/oxidative aromatization tandem reaction between tetrahydroisoquinolines and maleimides, and C-H arylation of heteroarenes with diazonium salts. The organic photocatalysts act as either electron acceptors (reductive quenching) or electron donors (oxidative quenching) in the single electron transfer (SET) of the catalytic cycles. Different from the widely used Ru(bpy)3[PF6]2, Ir(ppy)3, or halo-xanthane photocatalysts (Eosin Y or Rose Bengal), the new organic photocatalysts show strong absorption of visible light and long-lived triplet excited states, which are beneficial for SET, a crucial step for photoredox catalytic organic reactions. Moreover, the molecular structures of the new photocatalysts can be easily modified, as a result the absorption wavelength of the photocatalysts was readily tuned from 529 nm to 630 nm. The three different types of organic reactions are accelerated with the new organic photocatalysts (typical reaction times 1-2 h) compared to that catalyzed by Ru(bpy)3[PF6]2 or Ir(ppy)3 (reaction time: 12-72 h). The C-H arylation of thiophene with phenyl diazonium salts was used to prepare new Bodipy derivatives that show large Stokes shift. Our results are useful for designing of new organic catalysts for photoredox catalytic organic reactions to prepare highly functionalize organic compounds.
- Huang, Ling,Zhao, Jianzhang
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p. 23377 - 23388
(2013/11/19)
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- A Palladium Bipyridyl Complex Grafted onto Nanosized MCM-41 as a Heterogeneous Catalyst for Negishi Coupling
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The Negishi coupling of aryl bromides or acyl chlorides with organozinc chlorides catalyzed by a palladium bipyridyl complex anchored on nanosized mobile crystalline material 41 (MCM-41) were investigated. The reactions proceeded smoothly with a very low catalyst loading in THF at 70°C for electron-deficient aryl bromides, which gave good to high yields of the Negishi coupling products. However, reactions in toluene at 110°C were required if electron-rich aryl bromides were employed. For acyl chlorides, the reactions could be performed in THF at 50°C and the corresponding ketones and ynones were obtained in high yields. After centrifugation, it was possible to easily recover the supported catalyst from the reaction mixture, and this could be reused several times without any retreatment or regeneration with only a slight decrease in activity.
- Wu, Wei-Yi,Lin, Tze-Chiao,Takahashi, Tamotsu,Tsai, Fu-Yu,Mou, Chung-Yuan
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p. 1011 - 1019
(2013/05/09)
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- Room-temperature Suzuki-Miyaura coupling of heteroaryl chlorides and tosylates
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Suzuki-Miyaura coupling of heteroaryls is an important method for the preparation of compound libraries for medicinal chemistry and materials research. Although many catalysts have been developed, none of them have been generally applicable to the coupling reactions of heteroaryl chlorides and tosylates at room temperature. We discovered that a catalyst combination of Pd(OAc)2 and XPhos (2-dicyclohexylphosphanyl-2',4',6'- triisopropylbiphenyl) could efficiently catalyze these couplings. Besides the choice of catalyst, the use of hydroxide bases in an aqueous alcoholic solvent was essential for fast couplings. These conditions promoted fast release of active catalyst (XPhos)Pd0, and accelerated the transmetalation in the catalytic cycle. Most of the major families of heteroaryl chlorides (31 examples) and tosylates (17 examples) reached full conversion within minutes to hours at room temperature. The method could be easily scaled up for gram-scale synthesis. Furthermore, we examined the relative reactivity of coupling partners in whole reactions. Electron-rich heteroaryl chlorides and tosylates reacted more slowly than electron-deficient ones, in the order of indole, pyrrole furan, thiophene > pyridine. Similarly, electron-deficient arylboronic acids were less reactive than electron-neutral and electron-rich ones. The reactivity trends from this study can help to choose appropriate coupling partners for Suzuki reactions.
- Yang, Junfeng,Liu, Sijia,Zheng, Jian-Feng,Zhou, Jianrong
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supporting information
p. 6248 - 6259,12
(2020/09/16)
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- SBA-15-functionalized palladium complex partially confined with ionic liquid: An efficient and reusable catalyst system for aqueous-phase Suzuki reaction
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A novel SBA-15 functionalized palladium complex partially confined with 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid (Material 4) was found to be a very efficient and reusable catalyst in the Suzuki-Miyaura coupling reaction of aryl halides including aryl chlorides and heteroaryl halides with different aryl boronic acids under aqueous conditions without any organic co-solvents. Our studies showed that 4 is a more efficient catalyst in comparison with the catalyst not containing IL or catalyst with a higher ratio of IL. The materials were characterized by N2-sorption analysis, TGA and transmission electron microscopy before and after catalysis. While our studies showed that the catalyst can be successfully recycled and reused in at least 4 reaction runs, in contrast, several poisoning experiments and kinetic studies provide the notion that homogeneous (dissolved) species are responsible for the observed catalysis.
- Karimi, Babak,Zamani, Asghar
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supporting information; experimental part
p. 4531 - 4536
(2012/07/17)
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- Kumada-Tamao-Corriu coupling of heteroaromatic chlorides and aryl ethers catalyzed by (IPr)Ni(allyl)Cl
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The complex (IPr)Ni(allyl)Cl (IPr = 1,3-bis(2,6-diisopropylphenyl) imidazolidene) catalyzes the cross-coupling reactions of heteroaromatic chlorides with aryl Grignard reagents. Catalyst loadings as low as 0.1 mol % have been used to afford the products in excellent yields. This nickel-based catalytic system also promotes the activation of the CAr-O bond of anisoles in the Kumada-Tamao-Corriu reaction under fairly mild conditions.
- Iglesias, Maria Jose,Prieto, Auxiliadora,Nicasio, M. Carmen
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supporting information
p. 4318 - 4321
(2012/10/29)
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- A practical synthesis of biaryls and aromatic acetylenes by stille coupling in room-temperature ionic liquids
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The Stille cross-coupling reactions of aryl halides with aryl or alkynylstannanes have been achieved under mild conditions in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), affording the corresponding biaryls and aromatic acetylenes in good yields. Use of this solvent allows for facile recycling of the solvent and catalyst system, which can be used at least five times without loss of activity.
- Hao, Wenyan,Xi, Zhiwen,Cai, Mingzhong
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experimental part
p. 2396 - 2406
(2012/06/18)
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