Homocoupling of aryl halides in flow: Space integration of lithiation and FeCl₃ promoted homocoupling

• Aiichiro Nagaki,
• Yuki Uesugi,
• Yutaka Tomida and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2011, 7, 1064–1069, doi:10.3762/bjoc.7.122

• homocoupling of aryllithiums, and this enabled its integration with the halogen–lithium exchange reaction of aryl halides in a flow microreactor. This system allows the homocoupling of two aryl halides bearing electrophilic functional groups, such as CN and NO2, in under a minute. Keywords: homocoupling; iron

• mechanism. Radical coupling seems to be less likely. Conclusion In conclusion, we found that the use of FeCl3 results in fast oxidative homocoupling of aryllithiums, which enables its integration with the halogen–lithium exchange of aryl halides. Various aryl halides, including those bearing electrophilic

• halide followed by reaction with methanol. T-shaped micromixer: M1 (inner diameter: 250 μm), and M2 (inner diameter: 500 μm), microtube reactor: R1 and R2 ( = 1000 μm, length = 50 cm), a solution of aryl halides: 0.10 M in THF (6.0 mL/min), a solution of lithium reagent: 0.40 M or 0.42 M in hexane (n

Nano copper oxide catalyzed synthesis of symmetrical diaryl sulfides under ligand free conditions

• K. Harsha Vardhan Reddy,
• V. Prakash Reddy,
• A. Ashwan Kumar,
• G. Kranthi and
• Y.V.D. Nageswar

Beilstein J. Org. Chem. 2011, 7, 886–891, doi:10.3762/bjoc.7.101

• reactions mediated by recyclable copper oxide nanoparticles under ligand free conditions. This protocol avoids foul smelling thiols, for the synthesis of a variety of symmetrical diaryl sulfides, via the cross-coupling of different aryl halides with potassium thiocyanate, affording corresponding products in

• moderate to excellent yields. Keywords: aryl halides; aryl sulfides; copper oxide; cross-coupling; ligand free; potassium thiocyanate; recyclable; Introduction After the discovery of copper-promoted Ullmann reaction [1][2][3] for the construction of carbon-hetero atom bonds, several protocols have been

• cobalt [42] have been used in cross-coupling reactions, developed for the formation of carbon–sulfur bonds. Most of these coupling protocols involve the reaction between thiols and aryl halides, resulting in the formation of C–S bonds. Most of these metal-catalyzed reactions involve volatile and foul

Synthesis of chiral mono(N-heterocyclic carbene) palladium and gold complexes with a 1,1'-biphenyl scaffold and their applications in catalysis

• Lian-jun Liu,
• Feijun Wang,
• Wenfeng Wang,
• Mei-xin Zhao and
• Min Shi

Beilstein J. Org. Chem. 2011, 7, 555–564, doi:10.3762/bjoc.7.64

• aryl halides with arylboronic acids were carried out, and it was found that the electronic properties of the R groups and halide atoms significantly affected the reaction yield of the Suzuki–Miyaura reactions. The results have been summarized in Table 1. The [(NHC)Pd(allyl)I] complex 7 was also

• examined in the Heck–Mizoroki coupling reaction. Under optimized conditions (Supporting Information File 1), the reactions of various aryl halides with n-butyl acrylate were carried out in the presence of Na2CO3 in N,N-dimethylacetamide (DMA) at 140 °C. [(NHC)Pd(allyl)I] complex 7 showed good catalytic

A rapid and efficient synthetic route to terminal arylacetylenes by tetrabutylammonium hydroxide- and methanol-catalyzed cleavage of 4-aryl-2-methyl-3-butyn-2-ols

• Jie Li and
• Pengcheng Huang

Beilstein J. Org. Chem. 2011, 7, 426–431, doi:10.3762/bjoc.7.55

• limited to small-scale synthesis [13]. On the other hand, MEBYNOL ($ 0.3/g) is much cheaper than trialkylsilylacetylenes (TMSA $ 14.0/g, TIPSA $ 20.6/g, from Alfa Aesar). MEBYNOL couples with aryl halides in nearly quantitative yield and the coupling products 4-aryl-2-methyl-3-butyn-2-ols can be easily

• purified by chromatography because of the very different chromatographic polarities between the products and the aryl halides [13][14][15][16][17][18][19][20][21][22]. Nevertheless, the existing methods for the deprotection reaction (cleavage of 4-aryl-2-methyl-3-butyn-2-ols by removal of 2-hydroxypropyl

Air-stable, recyclable, and time-efficient diphenylphosphinite cellulose-supported palladium nanoparticles as a catalyst for Suzuki–Miyaura reactions

• Qingwei Du and
• Yiqun Li

Beilstein J. Org. Chem. 2011, 7, 378–385, doi:10.3762/bjoc.7.48

• catalyst; Suzuki–Miyaura reaction; Introduction The formation of Csp2–Csp2 bonds has long remained a difficult task until the development of the Suzuki–Miyaura palladium-catalyzed reaction [1][2][3]. The palladium-catalyzed Suzuki cross-coupling reaction of aryl halides with arylboronic acids is one of

• catalyst was enough to push the reaction to completion (Table 3, entry 3). To examine the scope for this coupling reaction, a variety of substituted aryl halides were coupled with different arylboronic acids in 95% ethanol in the presence of a catalytic amount of Cell–OPPh2–Pd0 (0.5 mmol % Pd) with K2CO3

• under reflux in air. aIsolated yield based on 4-iodoanisole. Preparation of the Cell–OPPh2–Pd0. Reaction of 4-iodoanisole with phenylboronic acid. Reaction of aryl halides with arylboronic acids. Effect of base on the Suzuki–Miyaura cross-coupling reactiona. Effect of solvent on the cross-coupling

Studies on Pd/NiFe₂O₄ catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

• Sanjay R. Borhade and
• Suresh B. Waghmode

Beilstein J. Org. Chem. 2011, 7, 310–319, doi:10.3762/bjoc.7.41

• Sanjay R. Borhade Suresh B. Waghmode Department of Chemistry, University of Pune, Ganeshkhind, Pune-411007, India 10.3762/bjoc.7.41 Abstract Palladium supported on nickel ferrite (Pd/NiF2O4) was found to be a highly active catalyst for the Suzuki coupling reaction between various aryl halides and

• catalysis; nickel ferrite; polyaryls; Suzuki reaction; terphenyls; Introduction Recently, transition metal catalyzed cross-coupling protocols have generated immense interest owing to their versatile applications in organic synthesis [1][2][3][4]. The Pd catalyzed Suzuki reaction between aryl halides with

• , but the conversion was too low to be of practical use. Using the preliminary optimized reaction conditions, we explored the general applicability of Pd/NiFe2O4 catalyst with various boronic acids and aryl halides containing electron withdrawing or donating substituents (Table 4). The Pd/NiFe2O4

SbCl₃-catalyzed one-pot synthesis of 4,4′-diaminotriarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

• Ghasem Rezanejade Bardajee

Beilstein J. Org. Chem. 2011, 7, 135–144, doi:10.3762/bjoc.7.19

• can be prepared by the palladium-catalyzed arylation of aryl(azaaryl)methanes with aryl halides [27], cationic Pd(II)/bipyridine-catalyzed addition of arylboronic acids to arylaldehydes [28], and by Friedel–Crafts type catalytic alkylation of aromatic rings with aromatic aldehydes and their imines [29

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• potential for a long time. Aryl halides activated by electron-withdrawing groups can only be converted at high temperatures (210 °C) using stoichiometric amounts of copper. The discovery of efficient copper/ligand systems enabled the use of catalytic amounts of metal under milder conditions (90–100 °C) and

• resulted in good yields [4][26]. Copper-diamine-catalysed N-arylation facilitated the arylation of pyrroles, pyrazoles, indazoles, imidazoles, triazoles, benzimidazoles and indoles [27][28][29]. Besides aryl halides as the aryl donor, arylsiloxanes [30], arylstannanes [31], iodonium salts [32], aryl lead

• series of aryl halides, aryl iodides 63 were the most active. The presence of air and water gave only slightly lower yields. Other heteroarylamines also gave good yields [39]. The copper-catalysed domino-indole synthesis facilitated access to new Chek1/KDR kinase inhibitors 67 from

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• sulfides [89][90][91][92]. It is well known that the reaction of non-activated aryl halides with phenols, thiophenols and amines are catalyzed effectively by copper (Ullmann reaction). L. M. Yagupol’skii [93][94][95][96][97] developed a related protocol for trifluoromethylsulfanylation of aromatic and

• carrying out the synthesis of aryltrifluoromethyl sulfides by generation CuSCF3 (from trifluoromethylthio mercury and -copper) in situ with the aryl halides. This not only reduces the number of steps but also increases the overall efficiency (Scheme 26). Aryl bromides can also be used but require higher

• trifluoromethylthiocopper [106]. Subsequent reaction with aryl halides results in the corresponding trifluoromethylsulfanyl derivatives (Scheme 29). Reduction of bis(perfluoroalkyl)disulfides with tetrakis(dimethylamino)ethylene produces tetrakis(dimethylamino)ethylene dication stabilized perfluoroalkyl thiolates. In

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• ][7][8][9][10][11][12], but is not strong enough to react with alkyl and aryl halides. The driving force for its oxidation is the attainment of some degree of aromaticity in the formation of its radical cation salt 2 on the loss of one electron, and full aromaticity in its dication salt 3 on loss of

• ][15][16][17] and notably the iodide CF3–I to trifluoromethyl anion, −CF3, [15] but is not powerful enough to react with aryl halides. Despite not experiencing any aromatic stabilization on oxidation, the molecule is such a good donor as a result of the ability of the nitrogen atoms in 5 to stabilize

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• . Various aryltriazenes were investigated as electrophilic substrates at room temperature to give biaryls in good to excellent yields and showed good chemoselectivity over aryl halides in the reactions. Keywords: 1-aryltriazenes; N-heterocyclic carbene–palladium complex; polymer-supported catalyst

• reaction has evolved as a powerful synthetic tool for the synthesis of unsymmetrical biaryls in both academic laboratories and industry [5][6][7][8]. Most of the reported Suzuki–Miyaura reactions are based on the use of aryl halides and triflates, and recently sulfonates and carboxylates, as the

• electrophilic component [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. As an additional candidate for the electrophilic coupling partner, arenediazonium salts have also been used in place of aryl halides in the Suzuki–Miyaura cross-coupling reaction, and show higher activity than the corresponding aryl

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• applicable reactions for carbon–carbon bond formation in organic synthesis. Over the last decade, several highly active catalyst systems have been developed for these reactions [4][5]. Usually, aryl halides are employed as starting materials [6][7][8][9], but other aryl sources such as aryl triflates [10][11

C-Arylation reactions catalyzed by CuO-nanoparticles under ligand free conditions

• Mazaahir Kidwai,
• Saurav Bhardwaj and
• Roona Poddar

Beilstein J. Org. Chem. 2010, 6, No. 35, doi:10.3762/bjoc.6.35

• aryl halides. The products were obtained in good to excellent yield. The catalyst can be recovered and reused for four cycles with almost no loss in activity. Keywords: active methylene compounds; C-arylation; heterogeneous catalyst; recyclability; Introduction Carbon-carbon (C–C) bond formation is

• various aryl halides and gave the corresponding products in 78–83% yield. It was observed that aryl halides having electron withdrawing groups showed greater reactivity and gave good yield of products compared to aryl halides having electron donating groups. All these results are summarized in Table 3

• . The above results encouraged us to investigate further reactions. Under similar reaction conditions, diethyl malonate was treated with iodobenzene to give the desired product in 78% yield (Scheme 3). The reaction was then repeated with a variety of aryl halides. The results are summarized in Table 4

Synthesis of novel photochromic pyrans via palladium- mediated reactions

• Christoph Böttcher,
• Gehad Zeyat,
• Saleh A. Ahmed,
• Elisabeth Irran,
• Thorben Cordes,
• Cord Elsner,
• Wolfgang Zinth and
• Karola Rueck-Braun

Beilstein J. Org. Chem. 2009, 5, No. 25, doi:10.3762/bjoc.5.25

• for the fine chemical industry, a variety of methods have been developed recently for the efficient cyanation of aryl halides under mild conditions. By applying electron-rich phosphanes and either Zn(CN)2 or K4[Fe(CN)6], the transformation of chlorides to nitriles was successfully achieved under

Synthesis of unsymmetrically substituted biaryls via sequential lithiation of dibromobiaryls using integrated microflow systems

• Aiichiro Nagaki,
• Naofumi Takabayashi,
• Yutaka Tomida and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2009, 5, No. 16, doi:10.3762/bjoc.5.16

• because of the frequent occurrence of such structures in natural products, pharmaceuticals, agrochemicals, and functional organic materials [1]. Transition metal-catalyzed cross-coupling of arylmetal compounds with aryl halides or triflates serves as a useful method for preparation of such unsymmetrical

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• donor in specific organometallic reactions, such as the chromium-mediated allylation of aldehydes and ketones [54][55] and the palladium-catalyzed reductive homo-coupling of aryl halides to afford the corresponding biaryls [56][57][58][59] illustrate further versatility of the reagent. The fact that

• arenediazonium cation) to the phenyl anion (+0.05 V vs SCE). Thus, it had long been noted that cyclic voltammetry of aryl halides, particularly iodides, can give rise to a single two-electron wave in the reductive part of the cycle. The first electron converts the aryl iodide to the corresponding aryl radical

EcoScale, a semi- quantitative tool to select an organic preparation based on economical and ecological parameters

• Koen Van Aken,
• Lucjan Strekowski and
• Luc Patiny

Beilstein J. Org. Chem. 2006, 2, No. 3, doi:10.1186/1860-5397-2-3

• claim that this procedure for preparing primary amides starting from aryl halides is better than another procedure which uses hexamethyldisilazane (HMDS). [26] Therefore, the EcoScale for the latter procedure was also calculated to compare the two preparations. The sum of all penalty points is 68 (Table