- Heterogeneous gold(I)-catalyzed cyclization between ynals and amidines: An efficient and practical synthesis of 2,4-disubstituted pyrimidines
-
A novel and highly efficient heterogeneous gold(I)-catalyzed cyclization between ynals and amidines has been developed that proceeds smoothly under mild conditions and provides a general and practical method for the synthesis of a wide variety of 2,4-disu
- Jiang, Minhua,Nie, Quan,Cai, Mingzhong
-
p. 2488 - 2500
(2019/07/12)
-
- Selective Methylation of Arenes: A Radical C?H Functionalization/Cross-Coupling Sequence
-
A selective, nonchelation-assisted methylation of arenes has been developed. The overall transformation, which combines a C?H functionalization reaction with a nickel-catalyzed cross-coupling, offers rapid access to methylated arenes with high para selectivity. The reaction is amenable to late-stage methylation of small-molecule pharmaceuticals.
- Serpier, Fabien,Pan, Fei,Ham, Won Seok,Jacq, Jér?me,Genicot, Christophe,Ritter, Tobias
-
p. 10697 - 10701
(2018/07/31)
-
- Facile one-pot nanocatalysts encapsulation of palladium-NHC complexes for aqueous Suzuki-Miyaura couplings
-
Organic transformations using water as the solvent have been the focus of intense investigation. We herein present a strategy that uses simple nanoparticle encapsulation to fabricate water-soluble nanocatalysts (NCs) for aqueous cross-coupling reactions. To achieve this goal, three types of N-heterocyclic carbene (NHC)-palladium (Pd) complexes (i.e., 1b, 2b, and 3b) with the chemical formula [PdL(CH3CN)Cl]PF6 (where L is a bidentate pyridine- or pyrimidine-bearing NHC ligand) have been synthesized, and their structures were characterized by NMR spectroscopy and X-ray crystallography. Exploiting a facile one-pot encapsulation process, the water-insoluble Pd-NHC complexes can be integrated into the hydrophobic cores of micelles composed of an amphiphilic copolymer. These water-dispersed nanoparticles exhibited excellent catalytic activity in aqueous Suzuki-Miyaura couplings. Among these NCs, 3b-NC, bearing a mesityl moiety on its NHC ligand, was found to be the most active catalyst under the tested reaction conditions. More impressively, 3b-NC can be reused for at least five cycles without substantial loss of catalytic activity.
- Chen, Chao,Zheng, Qing,Ni, Shengliang,Wang, Hangxiang
-
p. 4624 - 4630
(2018/03/21)
-
- Ruthenium-Catalyzed meta-Selective C?H Mono- and Difluoromethylation of Arenes through ortho-Metalation Strategy
-
The first example for the ruthenium-catalyzed ligand-directed meta-selective C?H mono- and difluoromethylation is developed, affording a variety of new meta-mono- and difluoromethylated 2-phenylpyridines, 2-phenylpyrimidines, and 1-phenylpyrazoles in moderate-to-good yields. This new transformation exhibits broad substrate scope, good functional group tolerance, and high efficiency, and offers a practical approach to synthesize mono- and difluoromethylated arenes. Mechanistic studies indicate that a reaction pathway involving palladium-initiated radical species is involved in the catalytic cycle. The new dual catalytic system consisting of compatible ruthenium(II) and palladium(0) complexes enables the key processes of C?H activation and mono-/difluoromethyl-radical formation to occur and achieves the meta-selective functionalization efficiently. In addition, the present protocol can also be extended to non-fluoromethylation.
- Li, Zhong-Yuan,Li, Liang,Li, Qi-Li,Jing, Kun,Xu, Hui,Wang, Guan-Wu
-
supporting information
p. 3285 - 3290
(2017/03/16)
-
- Systematic evaluation of HOMO energy levels for efficient dye regeneration in dye-sensitized solar cells
-
Thirty ruthenium complexes of the types [Ru(tctpy)(C^N)NCS] and [Ru(tctpy)(N^O)NCS] (C^N = cyclometalating ligand and N^O = pyridinecarboxylate and its derivatives) were synthesized and evaluated to identify the highest occupied molecular orbital (HOMO) energy level (EHOMO) for efficient dye regeneration in dye-sensitized solar cells. EHOMOof these complexes was systematically tuned by changing the electron-donating ability of the C^N and N^O ligands. For complexes with an EHOMOin the potential range more negative than 0.5 V vs. a saturated calomel electrode (SCE), the incident photon-to-current conversion efficiency (IPCE) increased with a positive shift in EHOMObut could not exceed 70%, suggesting that rapid dye regeneration is difficult. On the other hand, high IPCEs above 70% were often observed for complexes with an EHOMOmore positive than 0.5 V vs. SCE. It is thus concluded that there is a threshold for efficient electron transfer near 0.5 V vs. SCE (ΔG2≈ 0.3 eV) for the series of these sensitizers. This journal is
- Funaki, Takashi,Otsuka, Hiromi,Onozawa-Komatsuzaki, Nobuko,Kasuga, Kazuyuki,Sayama, Kazuhiro,Sugihara, Hideki
-
supporting information
p. 15945 - 15951
(2015/03/03)
-
- AMVN-initiated expedient synthesis of biaryls by the coupling reaction of unactivated arenes and heteroarenes with aryl iodides
-
The role of radical initiators AMVN and AIBN has been studied in the potassium tert-butoxide mediated biaryl coupling reaction of aryl iodides with unactivated arenes. Radical initiator AMVN promoted carbon-carbon bond formation expeditiously from aryl iodide having various groups such as amino, methoxy, fluoro, methyl, and trifluoromethyl and arenes in the presence of potassium tert-butoxide (4 equiv.) at 110 °C in 2-5 h. Substituted arenes such as toluene, xylene, anisole, and fluorobenzene also proceeded to form biaryls under AMVN-initiated reaction conditions. Moreover naphthalene, pyridine, pyrimidine, and pyridazine also coupled with aryl iodides and produced biaryls in 41-82% yields. It seems that AMVN initiates the formation of the aryl radical, which enters the radical chain reaction. The generated aryl radical may combine with the arene leading to a biaryl radical, which upon protonation gives the biphenyl radical anion and tert-butanol. The biphenyl radical anion finally reacts with the aryl iodide generating the aryl radical and thus completes the radical chain reaction with concomitant release of biphenyl.
- Bhakuni, Bhagat Singh,Yadav, Abhimanyu,Kumar, Shailesh,Kumar, Sangit
-
p. 827 - 836
(2014/02/14)
-
- Ruthenium-catalyzed double-fold C-H tertiary alkoxycarbonylation of arenes using di-tert-butyl dicarbonate
-
An efficient ruthenium-catalyzed double-fold C-H alkoxycarbonylation of arenes was developed using di-tert-butyl dicarbonate as the tertiary esterification reagent, which leads to a direct route to valuable 2,6-dicarboxylated products. This journal is
- Hong, Xiaohu,Wang, Hao,Liu, Bingxin,Xu, Bin
-
supporting information
p. 14129 - 14132
(2014/12/11)
-
- Copper-catalyzed aromatic C-H bond halogenation with lithium halides under aerobic conditions
-
A concise and practical Cu-catalyzed protocol for the preparation of chloro- and bromoarenes via C-H bond activation has been developed. The advantages of this strategy are the employment of cheap Cu(NO3) 2·3H2O, LiX and O2, and its compatibility with both electron-donating and electron-withdrawing substituents on aryl rings.
- Mo, Song,Zhu, Yamin,Shen, Zengming
-
supporting information
p. 2756 - 2760
(2013/05/08)
-
- Trinuclear copper(I) complex of 1,3-bis(2-pyridinylmethyl)imidazolylidene as a carbene-transfer reagent for the preparation of catalytically active nickel(II) and palladium(II) complexes
-
Reactions of 1,3-bis(pyridin-2-ylmethyl)-1H-imidazol-3-ium hexafluorophosphate, ([HL1](PF6), L1 = 1,3-bis(pyridin-2-ylmethyl) imidazolylidene) and 1,3-bis(pyridin-2-ylmethyl)-1H-benzimidazol-3-ium hexafluorophosphate ([HL2](PF6), L2 = 1,3-bis(pyridin-2-ylmethyl) benzoimidazolylidene) with cuprous oxide in acetonitrile readily yielded trinuclear complexes [Cu3(L1)3(PF6) 3] (1) and [Cu3(L2)3(PF6) 3] (2). Treatment of 1 with Ni(PPh3)2Cl 2 and Pd(cod)Cl2 gave [Ni(L1)Cl](PF6) (3) and [Pd(L1)Cl](PF6) (4), respectively, due to transmetalation. [Ni(L1)2](PF6)2 (5) was obtained from the reaction of [Cu3(L1)3(PF6)3] and Raney nickel in acetonitrile. All these complexes have been fully characterized. Both 1 and 2 consist of a triangular Cu3 core with each Cu-Cu bond capped by an imidazolylidene group. Each imidazolylidene acts as a bridging ligand in a μ2 mode and is bonded equally to two Cu(I) ions. The pincer nickel and palladium complexes are square-planar and contain a tridentate NCN ligand. Complexes 3 and 4 are efficient catalyst precursors for Kumada-Corriu and Suzuki-Miyaura coupling reactions of aryl halides with organometallic reagents.
- Chen, Chao,Qiu, Huayu,Chen, Wanzhi
-
scheme or table
p. 4166 - 4172
(2012/01/06)
-
- Kumada-Tamao-Corriu coupling of heteroaromatic chlorides and aryl ethers catalyzed by (IPr)Ni(allyl)Cl
-
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
-
supporting information
p. 4318 - 4321
(2012/10/29)
-
- Nickel-catalyzed cross-coupling of arene-or heteroarenecarbonitriles with aryl-or heteroarylmanganese reagents through C-CN bond activation
-
The nickel-catalyzed cross-coupling reaction of arene- or heteroarenecarbonitriles with aryl- or heteroarylmanganese reagents via C-CN bond activation has been developed. Both electron-rich and electron-deficient nitriles can be employed as the electrophilic substrates. The reaction tolerates a range of functional groups and aromatic heterocycles. Copyright
- Liu, Ning,Wang, Zhong-Xia
-
supporting information; experimental part
p. 1641 - 1645
(2012/07/31)
-
- An expeditious route toward pyrazine-containing nucleoside analogues
-
An improved and convenient methodology for the synthesis of asymmetrically substituted pyrazines starting from 3,5-dichloropyrazin-2(1H)-ones has been elaborated. Several nucleoside analogues have been synthesized containing the pyrazine core as the organic base coupled with the sugar via a triazole linkage. The beneficial effect of microwave irradiation throughout the sequence has been demonstrated.
- Modha, Sachin G.,Trivedi, Jalpa C.,Mehta, Vaibhav P.,Ermolat'ev, Denis S.,Van Der Eyckens, Erik V.
-
supporting information; experimental part
p. 846 - 856
(2011/04/17)
-
- Direct C-H arylation of electron-deficient heterocycles with arylboronic acids
-
A direct arylation of a variety of electron-deficient heterocycles with arylboronic acids has been developed. This new reaction proceeds readily at room temperature using inexpensive reagents: catalytic silver(I) nitrate in the presence of persulfate co-oxidant. The scope with respect to heterocycle and boronic acid coupling partner is broad, and sensitive functional groups are tolerated. This method allows for rapid access to a variety of arylated heterocycles that would be more difficult to access with traditional methods.
- Seiple, Ian B.,Su, Shun,Rodriguez, Rodrigo A.,Gianatassio, Ryan,Fujiwara, Yuta,Sobel, Adam L.,Baran, Phil S.
-
supporting information; experimental part
p. 13194 - 13196
(2010/11/05)
-
- Substituent-dependent structures and catalysis of benzimidazole-tethered N-heterocyclic carbene complexes of Ag(i), Ni(ii) and Pd(ii)
-
Homoleptic cationic benzimidazole-imidazolin-2-ylidene N-heterocyclic carbene (NHC = L) complexes of NiII and PdII have been prepared directly from the ligand precursor in salt form [H.L]Cl and from the transmetallation route via AgI. The N-tether of the imidazolinylidene ring imposes a significant influence on the nuclearity of the intermediate Ag(i)-NHC complexes and the geometric isomer outcome of the d8 products. Use of a benzyl-substituted NHC gives [Ag4(L Bn)2Cl4], 2a (from [HLBn]Cl, 1a, and Ag2O) (Bn = benzyl), which shows an alignment of four silver atoms bridged by the difunctional C-N ligands and chlorides. Its transmetallation with NiCl2(PPh3)4 and PdCl2(MeCN) 2 results in double-metal salts 2[M(LBn)2] 2+[Ag4Cl8]4- (M = Ni (3a) and Pd (4a)). The nuclearity of the Ag4 aggregate is maintained in the transmetallation process. Their Ag-free forms [M(LBn) 2]Cl2 (M = Ni (5) and Pd (6)) were prepared by direct deprotonation of 1a with M(OAc)2. The two carbenic carbon donor are cis- to each other in both 3a and 4a, thus imposing the weaker σ-benzimidazole nitrogen donor to be trans to them. A sterically demanding mesityl pendant however gives the dinuclear dissymmetic [Ag2(L Mes)2Cl2], 2b (Mes = mesityl) that shows a 12-membered metallomacrocyclic ring with a 2-coordinated [AgI(NHC) 2] and 4-coordinated [AgI(Imd)2Cl2] (Imd = imidazole). Transmetallation of the latter, or direct metallation from [HLMes]Cl, 1b, gives [M(LMes)2]Cl2 (M = Ni (3b) and Pd (4b)) with the two carbonic carbon trans to each other. The catalytic potential of 3b and 4b, which are more effective than 5 and 6, has been demonstrated by their high activities in Ni-catalyzed Kumada at room temperature and Pd-catalyzed Heck couplings of aryl and/or heteroaryl halides, respectively.
- Li, Fuwei,Hu, Jian Jin,Koh, Lip Lin,Hor, T. S. Andy
-
experimental part
p. 5231 - 5241
(2010/08/04)
-
- Palladium-catalyzed monoselective halogenation of C-H bonds: Efficient access to halogenated arylpyrimidines using calcium halides
-
A wide variety of ortho-halogenated arylpyrimidines were prepared with high monoselectivity and functional-group tolerance by using calcium halides as crucial halogenating agents and cupric trifluoroacetate as oxidant in the presence of air.
- Song, Bingrui,Zheng, Xiaojian,Mo, Jun,Xu, Bin
-
supporting information; experimental part
p. 329 - 335
(2010/04/28)
-
- Palladium-Catalyzed Regioselective C-H Bond ortho-Acetoxylation of Arylpyrimidines
-
An efficient and regioselective palladium-catalyzed ortho C-H acetoxylation reaction was developed to afford, ortho monoacetoxylated arylpyrimidmes in good to excellent yields by using cupric trifluoroacetate as a cocatalyst. A wide variety of oxygenated
- Zheng, Xiaojian,Song, Bingrui,Xu, Bin
-
supporting information; experimental part
p. 4376 - 4380
(2010/10/04)
-
- Cobalt(iii) complexes bearing bidentate, tridentate, and tetradentate N-heterocyclic carbenes: Synthesis, X-ray structures and catalytic activities
-
Cobalt(iii) complexes, [CoCl2(L1)2](PF6) (1, L1 = N-methyl-N-(2-pyrimidinyl)imidazolylidene), [CoCl(L2) 2](PF6)2 (2, L2 = N-picolyl-(2-pyrimidinyl) imidazolylidene), [Co(L3)2](PF6)3 (3, L3 = bis(N-2-pyrimidylimidazolylidenyl)methane) and [CoCl2(L3)](PF 6) (4) have been prepared from the corresponding pyrimidine functionalized imidazolium salts [HL1](PF6), [HL2](PF6), and [H2L3](PF6)2via in situ generated silver carbene complexes under mild conditions. These cobalt complexes were characterized by 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The cobalt complexes have been found to be good catalyst precursors for Kumada-Corriu cross-coupling reactions of aryl halides and Grignard reagents at room temperature. Complex 1 is more active under the mild conditions.
- Xi, Zhenxing,Liu, Bin,Lu, Chunxin,Chen, Wanzhi
-
experimental part
p. 7008 - 7014
(2010/01/06)
-
- Simple mixed Fe-Zn catalysts for the Suzuki couplings of tetraarylborates with benzyl halides and 2-halopyridines
-
Employing co-catalytic zinc reagents facilitates the iron-catalysed Suzuki cross-coupling of tetraarylborates with both benzyl and 2-heteroaryl halides.
- Bedford, Robin B.,Hall, Mark A.,Hodges, George R.,Huwe, Michael,Wilkinson, Mark C.
-
supporting information; experimental part
p. 6430 - 6432
(2010/03/03)
-
- Mild room-temperature palladium-catalyzed C3-arylation of 2(1H)-pyrazinones via a desulfitative kumada-type cross-coupling reaction
-
(Chemical Equation Presented) An efficient desulfitative Kumada-type cross-coupling protocol is reported for the C3-arylation of 5-chloro-3- (phenylsulfanyl)pyrazin-2(1H)-ones. The method has also been successfully extended to the arylation of some (heter
- Mehta, Vaibhav P.,Modha, Sachin G.,Van Der Eycken, Erik
-
supporting information; experimental part
p. 6870 - 6873
(2009/12/30)
-
- Room-temperature Kumada cross-coupling of unactivated aryl chlorides catalyzed by N-heterocylic carbene-based nickel(II) complexes
-
(Chemical Equation Presented) The Kumada cross-coupling reaction of a variety of unactivated aryl chlorides, vinyl chlorides, and heteroaryl chlorides catalyzed by nickel(II) complexes containing pyridine-functionalized NHC ligands is described. The catalysts are so active that the reactions proceed at room temperature in excellent yields.
- Xi, Zhenxing,Liu, Bin,Chen, Wanzhi
-
p. 3954 - 3957
(2008/09/19)
-
- Efficient Negishi coupling reactions of aryl chlorides catalyzed by binuclear and mononuclear nickel-N-heterocyclic carbene complexes
-
(Chemical Equation Presented) We describe the first nickel-N-heterocyclic carbene catalyzed Negishi cross-coupling reaction of a variety of unactivated aryl chlorides, heterocyclic chlorides, aryl dichlorides, and vinyl chloride. The mononuclear and binuclear nickel-NHC complexes supported by heteroarene-functionalized NHC ligands are found to be highly efficient for the coupling of unactivated aryl chlorides and organozinc reagents, leading to biaryls and terphenyls in good to excellent yields under mild conditions. For all aryl chlorides, the binuclear nickel catalysts show activities higher than those of mononuclear nickel complexes because of possible bimetallic cooperative effect.
- Xi, Zhenxing,Zhou, Yongbo,Chen, Wanzhi
-
experimental part
p. 8497 - 8501
(2009/04/04)
-
- Ueber die Herstellung von Styryl- und Stylbenyl-Derivaten des Pyrimidins
-
2- and 4-(p-Tolyl)-substituted pyrimidines react with anils of hetero-aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide or potassium t-butoxide to yield the corresponding 2- and 4-pyrimidines or
- Burdeska, Kurt,Fuhrer, Hermann,Kabas, Guglielmo,Siegrist, Adolf Emil
-
p. 113 - 152
(2007/10/02)
-