Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

• Yi Lai,
• Zhijian Zong,
• Yujie Tang,
• Weimin Mo,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen,
• Liqun Jin,
• Wen-hua Sun and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 213–221, doi:10.3762/bjoc.13.24

• between chlorobenzene and phenylboronic acid was carried out and 64% isolated yield was obtained (Table 4, entry 1). Subsequently, different aryl chlorides and arylboronic acids were tested. The results were listed in Table 4. Aryl chlorides with an electron-withdrawing functional group, such as nitro

• , entries 13). Different arylboronic acids were also examined to react with 4-chloroacetophenone in this system. No matter what kind of boronic acids were used: electron-deficient (Table 4, entry 14), electron-rich (Table 4, entries 15 and 16) or sterically hindered (Table 4, entry 17) arylboronic acids

• activities the importance of bulkier groups at the imino moiety for the stabilization of the palladium species was sown. A variety of aryl chlorides and arylboronic acids were successfully coupled in high yields and selectivity. Experimental General procedures All reactions were carried out under air

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

• Youngeun Jung,
• Dileep Kumar Singh and
• Ikyon Kim

Beilstein J. Org. Chem. 2016, 12, 2689–2693, doi:10.3762/bjoc.12.266

• shoreaphenol [13]. Under similar reaction conditions, several other arylboronic acids reacted with 13 to give the corresponding products in good yields, demonstrating the general usefulness of this route for the synthesis of a range of structural analogues at a late stage. The direct Friedel–Crafts type

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• developed the first direct sp3 C–H arylation of THIQ with arylboronic acids using a copper catalyst (Scheme 1) [30]. Oxygen gas and tert-butyl hydroperoxide (TBHP) were used as external oxidants, which gave moderate to good isolated yields (up to 75%). In addition, we demonstrated the first enantioselective

• , entry 2). N-Aryl-substituted THIQs gave high er, when either EDG or EWG were present (Table 3, entries 3–6). High and moderate enantiomeric ratios were obtained, respectively, when vinyl-substituted arylboronic acids and fluoro-substituted arylboronic acids were subjected to the reaction system (Table 3

• for the direct asymmetric arylation of N-arylated tetrahydroisoquinolines (THIQs) with arylboronic acids. Using [Ir(ppy)2(dtbbpy)]PF6 as photoredox catalyst provided a novel facile method to build important arylated compounds in very high yields under very mild conditions. The combination of copper

Rapid regio- and multi-coupling reactivity of 2,3-dibromobenzofurans with atom-economic triarylbismuths under palladium catalysis

• Maddali L. N. Rao,
• Jalindar B. Talode and
• Venneti N. Murty

Beilstein J. Org. Chem. 2016, 12, 2065–2076, doi:10.3762/bjoc.12.195

• -dibromobenzofuran with arylboronic acids under palladium catalyzed conditions [29][30]. Bach et al. reported site-selective studies involving the Sonogashira, Negishi, Kumada cross-couplings employing 2,3-dibromobenzofuran and 2,3,5-tribromobenzofuran substrates [31][32][33]. Additionally, Langer et al. reported

• -pot operation are on par with that obtained in Table 5. This reflects the efficient nature of our established pot-economic protocol employing different triarylbismuth reagents. In literature, bis-aryl couplings with arylboronic acids were reported with good reactivity under different heating

• advantageous. This reactivity is on par with similar study reported with arylboronic acids [30]. Thus the present method of the preparation of 2,3,5-triarylbenzofurans is expected to serve as a useful protocol to access these skeletons in a facile manner. Conclusion We have established the couplings of 2,3

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• Abstract A flow system to perform Chan–Lam coupling reactions of various amines and arylboronic acids has been realised employing molecular oxygen as an oxidant for the re-oxidation of the copper catalyst enabling a catalytic process. A tube-in-tube gas reactor has been used to simplify the delivery of the

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• this context, Reetz and co-workers were the first to report the transition metal-catalyzed enantioselective addition of arylboronic acids to an α-substituted-α,β-unsaturated ester to provide enantioenriched phenylalanine derivatives 48a (Scheme 10) [29]. Notably, a BINAP-derived rhodium(I) catalyst was

• enantioselective synthesis of β-amino esters 62 via the addition of arylboronic acids 47 to α-methylaminoacrylates 61 (Scheme 14) [35]. The authors identified (S)-difluorphos (44, Figure 2) and phthalimide as the optimal ligand and proton source combination, respectively. Additionally, the bulky tert-butyl ester

• was necessary for achieving both good reactivity and enantioselectivity. All of the arylboronic acids investigated, except 4-methylphenylboronic acid, added in good yield and enantioselectivity (70–95% yield, 92:8 to 95.5:4.5 er). In 2007, Frost and co-workers reported a rhodium catalyzed conjugate

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• arylureas at room temperature. A commercially available catalyst [Pd(MeCN)4](BF4)2 or a nitrile-free cationic palladium(II) complex generated in situ from the reaction of Pd(OAc)2 and HBF4, effectively catalyzes C–H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates

• C–H arylations of arylureas with aryl iodides and arylboronic acids Among the most conceptually attractive approaches to aromatic C–H activation is the efficient synthesis of biaryls through direct arylation reactions. The widespread availability of aryl iodides and arylboronic acids make them

• ](BF4)2 [184], was found to efficiently catalyze the reaction between arylureas and arylboronic acids. On the other hand, C–H arylations with aryl iodides catalyzed by [Pd(MeCN)4](BF4)2 did not give any of the desired products (see mechanistic discussion; vide infra). Various neutral palladium catalysts

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• alkoxide species C. Reductive elimination of species C gave the product and regenerated the active iridium catalyst. Recently, Qiu and co-workers developed a novel chiral ligand L5 based on a chiral-bridged biphenyl backbone and successfully achieved the asymmetric addition of arylboronic acids to N

• arylboronic acids, as well as the rigidity of the ligand had remarkable influence on the yields and stereoselectivity. Increase of the rigidity can improve the yields and stereoselectivity. Other metal-catalyzed syntheses of 3-hydroxyoxindoles Aside from above mentioned metal catalysts, several other metal

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• Pharmacological Sciences, via Marzolo 5, 35131 Padova, Italy University of Padova, Department of Woman’s and Child’s health, 35128 Padova, Italy 10.3762/bjoc.12.84 Abstract Cationic biaryl derivatives were synthesized by Suzuki–Miyaura coupling of 3-bromonaphtho[1,2-b]quinolizinium bromide with arylboronic acids

• -benzylpyridinium derivative 3 and the subsequent cyclodehydration [27] in refluxing HBr (w = 48%) gave the bromonaphtho[1,2-b]quinolizinium 4 in 57% overall yield (Scheme 1). The Suzuki–Miyaura coupling reactions of 3-bromonaphthoquinolizinium derivative 4 with the arylboronic acids 5a–e were performed under

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• substituted 3,5-diaryl-2,4,6-trimethylpyridines were prepared and characterized using the Suzuki–Miyaura coupling reaction with accordingly selected bromo-derivatives and arylboronic acids. The reaction conditions were carefully optimized allowing high yield of isolated products and also the construction of

• leading to a number of different 2,4- and 2,5-diaryldimethylpyridines P3, P4 [25], 4-benzylpyrimidines P2 [26], and 4-methyl-5-arylpyrimidines P1 [26] was needed. For this purpose, we successfully used Suzuki and Negishi cross-coupling reactions between arylboronic acids/benzylzinc reagents and

• less susceptible to the cross-coupling reaction. If the steric repulsion of the pyridine methyl group, at least in part, corresponds to its van der Waals radii, the degree of steric repulsion of the selected ortho-substituents in arylboronic acids can be listed in the following order: I > Br > Me > Cl

Iridium/N-heterocyclic carbene-catalyzed C–H borylation of arenes by diisopropylaminoborane

• Mamoru Tobisu,
• Takuya Igarashi and
• Naoto Chatani

Beilstein J. Org. Chem. 2016, 12, 654–661, doi:10.3762/bjoc.12.65

• (Scheme 1). The most commonly used boron sources are pinacolborane (HBpin, 1a) and bis(pinacolato)diboron (B2pin2, 1b), which form pinacol esters of arylboronic acids. Although the pinacol ester products prepared in these reactions are amenable to a range of transformations, their reactivity is generally

Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes

• H. Surya Prakash Rao and
• A. Veera Bhadra Rao

Beilstein J. Org. Chem. 2016, 12, 496–504, doi:10.3762/bjoc.12.49

• which the final step is the copper(II)-catalyzed arylation of diarylmethanols with arylboronic acids. By using this protocol a variety of symmetrical and unsymmetrical triarylmethanes were synthesized. As an application of the newly developed methodology, we demonstrate a high-yielding synthesis of the

• variety of triarylmethanes through substitution of C(sp3)–OH in diarylmethanols with arylboronic acids (Scheme 1B). We reasoned that since diarylmethanols with two different aromatic rings can be made by a wide variety of methods [53][54] (e.g., addition of an aryl carbanion to an aryl aldehyde and a

• report a copper(II) triflate-catalyzed modular synthesis of triarylmethanes by employing diarylmethanols 9 and arylboronic acids 10. It is advantageous to employ a base metal catalyst such as copper(II) triflate instead of palladium [55][56] or nickel (Ni) [57] catalysts and to avoid the use of phosphine

Carbon–carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

• Tsuyuka Sugiishi,
• Hideki Amii,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2015, 11, 2661–2670, doi:10.3762/bjoc.11.286

• (Scheme 12). The copper-mediated oxidative trifluoromethylation of arylboronic acids are important reactions in organic chemistry because arylboronic acids are widely used. Oxidative, aromatic perfluoroalkylation reactions with arylboronic acid derivatives have been studied by several groups. Qing et al

• − sources for perfluoroalkylation reactions. Furthermore, CF3Cu and C2F5Cu were utilized for oxidative perfluoroalkylation reactions of arylboronic acids [44][45] (Scheme 13). Copper-catalyzed group transfer from fluoral derivatives Catalytic systems in organic synthesis are desirable from an

• determined by 19F NMR analysis using benzotrifluoride (BTF) or (trifluoromethoxy)benzene as an internal standard. bIsolated yield. c4 equivalents of CF3CF2Cu reagent were used. Perfluoroalkylation reactions of arylboronic acids. aIsolated yield. bDMF was used instead of toluene as a solvent. c4 equivalents

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

• Carmen Mejuto,
• Beatriz Royo,
• Gregorio Guisado-Barrios and
• Eduardo Peris

Beilstein J. Org. Chem. 2015, 11, 2584–2590, doi:10.3762/bjoc.11.278

• addition reaction of arylboronic acids to α,β-unsaturated ketones. Keywords: arylation of unsaturated ketones; mesoionic carbenes; nickel; iridium; rhodium; Introduction Highly symmetrical poly-NHCs are a very interesting type of ligands, because they allow the preparation of a variety of supramolecular

• the addition reaction of arylboronic acids to 2-cyclohexen-1-one, where it showed good activity. The same ligand was also used for the preparation of nanometer-sized cylinder-like structures of Cu, Ag and Au [13]. As mesoionic carbenes (MICs) are known to be stronger electron donors compared to NHCs

• of the tris-MIC ligand B with those of its tris-NHC analogue, A. The catalytic activity of the tris-MIC-trirhodium complex was tested in the addition reaction of arylboronic acids to 2-cyclohexen-1-one and compared to the results obtained with the tris-NHC analogue. Results and Discussion Complex 2

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• -science [6][18][33][34][35][36][37][38], and material sciences [5][19][38][39] are emerging. Arylboronic acids and arylboronates represent versatile building blocks in organic synthesis [40]. They have found wide applications in transition metal-catalyzed cross-coupling reactions [41][42]. These boron

• potassium SF5-phenyltrifluoroborates were found to be highly reactive with a variety of aryl bromides and iodides in the presence of catalytic amounts of PdCl2(dppf)·CH2Cl2 or Pd(OAc)2 [72]. The recently published synthesis of arylboronic acids from anilines or aryldiazonium tetrafluoroborates using B2(OH)4

Weakly nucleophilic potassium aryltrifluoroborates in palladium-catalyzed Suzuki–Miyaura reactions: relative reactivity of K[4-RC₆F₄BF₃] and the role of silver-assistance in acceleration of transmetallation

• Vadim V. Bardin,
• Anton Yu. Shabalin and
• Nicolay Yu. Adonin

Beilstein J. Org. Chem. 2015, 11, 608–616, doi:10.3762/bjoc.11.68

• nucleophilic organoboron reagents (alkyl- and cyclopropylboronic acids and esters [10][11][12][13][14], alken-1-ylboronic acids and esters [15][16], some arylboronic acids [17][18][19], K[CF2=CFBF3] [19]) often are accelerated by the addition of stoichiometric amounts of Ag2O. Initially this phenomenon was

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• -catalyzed reactions [125]. One of the first examples of a rhodium-catalyzed asymmetric 1,4-addition of lactams was reported by Hayashi and co-workers [136]. They reported that the key to achieving high yields for this reaction was to use arylboroxines instead of arylboronic acids and the addition of 1 equiv

A novel 4-aminoantipyrine-Pd(II) complex catalyzes Suzuki–Miyaura cross-coupling reactions of aryl halides

• Claudia A. Contreras-Celedón,
• Darío Mendoza-Rayo,
• José A. Rincón-Medina and
• Luis Chacón-García

Beilstein J. Org. Chem. 2014, 10, 2821–2826, doi:10.3762/bjoc.10.299

• are tolerated. Keywords: 4-aminoantipyrine; arylboronic acids; biaryls; cross-coupling; palladium(II) complex; Introduction The sp2–sp2 carbon–carbon bond formation through cross-coupling reactions catalyzed by metal complexes has emerged as a powerful tool in organic synthesis [1][2][3][4][5][6

• organic reactions. Synthesis of 4-aminoantipyrine-Pd(II) complex. Reaction of different aryl halides with substituted arylboronic acids. Reaction conditions: phenylboronic acid (0.40 mmol), aryl halide (0.27 mmol), 4-AAP–Pd(II) (0.3 mol %), 2 M K2CO3 (0.67 mmol), ethanol (2 mL), heating under reflux for 4

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• opportunity to vary the pendent substituent through a Pd-catalyzed cross-coupling protocol (Scheme 2). Thus, pentacene 3g was treated under Suzuki–Miyaura coupling conditions with arylboronic acids, and the desired pentacenes 3j,k were obtained in yields of 92 and 68%, respectively. Notably, anthracenyl

Stereoselective synthesis of carbocyclic analogues of the nucleoside Q precursor (PreQ₀)

• Sabin Llona-Minguez and
• Simon P. Mackay

Beilstein J. Org. Chem. 2014, 10, 1333–1338, doi:10.3762/bjoc.10.135

• introduction of diverse aryl groups at the 3-position of the cyclohexane ring using commercially available arylboronic acids as building blocks, and Pd catalysis to form the new C–C bond, followed by a highly diastereoselective ketone-to-amine conversion. Others have reported on similar preparations of 3

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• -(aryl)arylphosphonic acid monoethyl esters were efficiently prepared by a Suzuki reaction of 2-bromoiodoarenes with arylboronic acids, a lithium bromide exchange reaction of 2-bromobiaryls followed by diethylphosphinylation with diethyl chlorophosphate, and the C–O cleavage of diethyl 2-(aryl

Palladium-catalysed cross-coupling reaction of ultra-stabilised 2-aryl-1,3-dihydro-1H-benzo[d]1,3,2-diazaborole compounds with aryl bromides: A direct protocol for the preparation of unsymmetrical biaryls

• Siphamandla Sithebe and
• Ross S. Robinson

Beilstein J. Org. Chem. 2014, 10, 1107–1113, doi:10.3762/bjoc.10.109

• cross-coupling; Introduction Arylboronic acids 1, arylboronate esters 2 and potassium aryltrifluoroborate salts 3 (Figure 1) have received considerable attention and have found a special place as mild and versatile nucleophilic coupling partners for carbon–carbon bond-forming cross-coupling reactions

• counterpart (13e) only affording the coupled products in moderate yields (Table 3, entries 9–11). Conclusion Although arylboronic acids, arylboronate esters and potassium aryltrifluoroborate salts are powerful coupling partners in the Suzuki–Miyaura cross-coupling realm, extending the scope of organoboron

• Siphamandla Sithebe Ross S. Robinson Warren Laboratory, School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South Africa 10.3762/bjoc.10.109 Abstract There has been a significant interest in organoboron compounds such as arylboronic

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

A new manganese-mediated, cobalt-catalyzed three-component synthesis of (diarylmethyl)sulfonamides

• Antoine Pignon,
• Erwan Le Gall and
• Thierry Martens

Beilstein J. Org. Chem. 2014, 10, 425–431, doi:10.3762/bjoc.10.39

• -supported benzotriazole [7] with arylmagnesium reagents, addition of phenyllithium to selenoamides [8], addition of organometallic species [9][10][11][12][13][14][15][16][17][18][19][20][21] or arylboronic acids [22][23][24][25][26][27] to imines, reaction of organolithium and Grignard reagents with

Cu-Mediated trifluoromethylation of benzyl, allyl and propargyl methanesulfonates with TMSCF₃

• Xueliang Jiang and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2013, 9, 2862–2865, doi:10.3762/bjoc.9.322

• -mediated trifluoroethylation of arylboronic acids [13][14] (Scheme 1a) and trifluoromethylation of benzyl halides [15][16][17][18][19][20][21] (Scheme 1b) are more convenient. Especially trifluoromethylations of benzyl bromides with a [CuCF3] species, which are generated from different precursors, are