Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• conditions to avoid the formation of hydroxide ions. To avoid the potential interference of bases, we attempted to improve of the conditions for the Suzuki–Miyaura coupling in the base-free variant using aryldiazonium reagents [39]. Although the coupling reactions between aryldiazonium salts and arylboronic

• acids or esters with base-free conditions are known [39][42], in our hands the reaction of benzo[b]quinolizinium-9-boronic acid (3a) with benzenediazonium tetrafluoroborate 4a only resulted in the formation of the benzo[b]quinolizinium-9-trifluoroborate (3b). Consequently, we used the latter substrate

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

•  20. In 2016, Zhang and Yang reported an asymmetric palladium-catalyzed addition of arylboronic acids 60 to sterically hindered N-tert-butylsulfonylisatin imines 61 [80]. Among a variety of chiral ligands investigated, including different pyridine-oxazolines, oxazolines and (R)-BINAP, the chiral

• presence of various substituents (R1) at different positions of the aryl moiety of isatin imines, giving comparable enantioselectivities (91–94% ee). Moreover, the arylboronic acid scope was also found wide and various para- as well as meta-substituted arylboronic acids reacted smoothly, giving the

• products in high yields (81–96%) and enantioselectivities (93–96% ee). Good yields (82–85%) and high enantioselectivities (92–96% ee) were also obtained for disubstituted arylboronic acids. Even a heteroaromatic boronic acid (Ar = 2-thienyl) was tolerated, providing the corresponding product in excellent

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• quantitative yields were observed when aryl chloride coupling was performed with arylboronic acids. This is indeed remarkable as aryl chlorides are generally not as reactive as aryl bromides or aryl iodides. Lipshutz and Ghorai developed a micellar system called PQS to perform aldol reactions in water [25]. As

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• relatively inexpensive CF3I. Besides, the easy conversion of CF3I to CF3 radical at room temperature with visible light developed by MacMillan facilitated these method [38][39]. On the basis of the former work, the group of Sanford [40] designed the cross-coupling of arylboronic acids with CF3I via the

• trifluoromethyl radical was generated from CF3SO2Na in the presence of TBHP at room temperature using a mixture of water and DCM as solvent. Arylboronic acids with electron-donating substituents proceeded smoothly to give the corresponding products in good yields. Common hydroxy protecting groups (Bn and TBS

• . Trifluoromethylation of boronic acid derivatives reported by the group of Liu. Trifluoromethylation of organotrifluoroborates reported by the group of Huang. Trifluoromethylation of aryl- and vinylboronic acids reported by the group of Shibata. Trifluoromethylation of arylboronic acids via the merger of photoredox and

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• necessitated (MeCN)4CuPF6 and a base, NaHCO3, to allow the trifluoromethylation to proceed in good yields (Scheme 53) [78]. In the continuity of Sanford’s work, Beller’s group reported the synthesis of trifluoromethylated arenes from arylboronic acids as well as trifluoromethylated vinylarenes [79]. The

• substrate scope was realised on 17 arylboronic acids and 8 vinylboronic acids (Scheme 54). The protocol was robust and tolerated various functional groups. However, large excesses of both CF3SO2Na and TBHP were required. In this process, a ligand, 2,4,6-collidine, was used in order to increase the yield of

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• reaction under mechanomilling [67]. Asymmetric alkynylation of prochiral sp3 C–H bonds via CDC [68]. Fe(III)-catalyzed CDC coupling of 3-benzylindoles [69]. Mechanochemical synthesis of 3-vinylindoles and β,β-diindolylpropionates [70]. Mechanochemical C–N bond construction using anilines and arylboronic

• acids [78]. Mechanochemical amidation reaction from aromatic aldehydes and N-chloramine [79]. Mechanochemical CDC between benzaldehydes and benzyl amines [81]. Mechanochemical protection of -NH2 and -COOH group of amino acids [85]. Mechanochemical Ritter reaction [87]. Mechanochemical synthesis of

Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid

• Kohei Yamada,
• Naoto Kamimura and
• Munetaka Kunishima

Beilstein J. Org. Chem. 2017, 13, 1478–1485, doi:10.3762/bjoc.13.146

• , Jin and co-workers reported that Ni-catalyzed Suzuki–Miyaura coupling between triazinyloxybenzene and arylboronic acids affords the corresponding biaryl compounds [24][25][26][27][28][29][30][31][32][33]. In this context, we envisioned application of this Suzuki–Miyaura coupling to a 5-(triazinyloxy

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

• Adesh Kumar Singh,
• Varsha Tiwari,
• Kunj Bihari Mishra,
• Surabhi Gupta and
• Jeyakumar Kandasamy

Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113

• available, inexpensive and nontoxic. The application of UHP as oxidant is well explored in various solution- as well as solid-phase organic syntheses [25][26][27][28]. In fact, we have recently reported the oxidation of arylboronic acids into corresponding phenols by using UHP as a selective oxidizing agent

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• 55 via a formal 1,4-addition of arylboronic acids to β-aryl-α,β-unsaturated ketones and esters [39]. Thus, the α,β-unsaturated diester 52 was coupled with arylboronic acid in the presence of rhodium(I)/Chiraphos® complex as a catalyst to obtain derivative 53, which next underwent a Claisen

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