Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• alkenes and alkylation/arylation using organic halides [29][30]. These previous studies have prompted us to expand the scope of cobalt catalysis for the C–H alkenylation and thus to develop an ortho C–H alkenylation reaction of pivalophenone N–H imine with alkenyl phosphates using a new cobalt–NHC

• , the NHC precursor featuring a cyclohexane backbone and 2,6-diethylphenyl groups (L1·HBr), which proved to be the optimal ligand for the C–H arylation of pivalophenone N–H imine as well as for the C–H alkenylation of N-arylimine (Scheme 1a, b) [28][29], was not particularly effective for the present

• reaction (Table 1, entry 8). To our delight, we observed a remarkable improvement in the reaction efficiency using the benzofused analogue of IPr·HCl (L2·HCl), affording 3aa in 88% yield without any trace of a dialkenylation product (Table 1, entry 9). It should be noted that, unlike the C–H arylation of

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

• Romain Sallio,
• Stéphane Lebrun,
• Frédéric Capet,
• Francine Agbossou-Niedercorn,
• Christophe Michon and
• Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

• -receptor agonists [8][9][10][11][12][13][14][15][16]. Indeed, the copper-catalyzed N-arylation of (3S)-26 was performed in dioxane with N,N-dimethylethylenediamine as ligand [27] to deliver the targeted pazinaclone analogue (3S)-27 in a fair yield (66%) without significant loss in enantiomeric purity

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• successfully developed a rhodium-catalyzed asymmetric arylation process leading to triarylmethanes 25. With the application of mild reaction conditions (40 °C, 15 h), a high enantioselectivity (≥90% ee) was reached with good to excellent yields. (Scheme 2). Starting from 2-naphthol, 2,2-disubstituted 3

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• of the corresponding imidoyl chlorides 10 with PCl5 in POCl3, followed by the additional reaction with trifluoromethanesulfonamide (1) and protonation by sulfuric acid (Scheme 1) [10]. In recent years, we have reported high yielding catalyst-free N-arylation by SNAr reaction of mono- or

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• ]. Later on, arylation, vinylation and alkynylation of glycine derivatives were also accomplished by the same group (Scheme 1) [13]. Using the Cu(OAc)2/pyrrolidine dual catalysts system, Huang developed the oxidative cross coupling of glycine derivatives with acetone in the presence of TBHP or DDQ as

Syn-selective silicon Mukaiyama-type aldol reactions of (pentafluoro-λ⁶-sulfanyl)acetic acid esters with aldehydes

• Anna-Lena Dreier,
• Andrej V. Matsnev,
• Joseph S. Thrasher and
• Günter Haufe

Beilstein J. Org. Chem. 2018, 14, 373–380, doi:10.3762/bjoc.14.25

• SF5X (X = Cl, Br, SF5) across π-bonds. The unconventional conditions usually required were overcome by Dolbier’s elegant triethylborane initiation [21]. Recently, the radical arylation of a SF5-substituted alkene was realized in order to gain access to SF5-containing dihydrobenzofurans and indolines

Synthesis of fluoro-functionalized diaryl-λ³-iodonium salts and their cytotoxicity against human lymphoma U937 cells

• Prajwalita Das,
• Etsuko Tokunaga,
• Hidehiko Akiyama,
• Hiroki Doi,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2018, 14, 364–372, doi:10.3762/bjoc.14.24

• arylation reactions in synthetic organic chemistry, but their biological properties are not fully understood. Herein, after initially investigating 18 fluoro-functionalized reagents, we discovered that the ortho-fluoro-functionalized diaryliodonium salt reagents showed remarkable cytotoxicity in vitro

Diels–Alder cycloadditions of N-arylpyrroles via aryne intermediates using diaryliodonium salts

• Huangguan Chen,
• Jianwei Han and
• Limin Wang

Beilstein J. Org. Chem. 2018, 14, 354–363, doi:10.3762/bjoc.14.23

• photosensitive dyes. Keywords: benzyne; cycloaddition; diaryliodonium salts; N-phenylamine; pyrrole; Introduction Pyrrole is a very useful heterocyclic substrate to produce structural attributes of valuable chemicals, functional materials and pharmaceuticals [1][2][3][4][5]. Recently, arylation of pyrrole

• derivatives with diaryliodonium salts for pyrrole–aryl coupling products is generating tremendous academic interest in organic synthesis. In 2012, the Zhang and Yu group reported that sodium hydroxide promoted direct arylation of unprotected pyrroles with diaryliodonium salts at the temperature of 80 °C, the

• diaryliodonium salts can generate benzynes under severe basic conditions, the resulted benzynes were allowed to undergo cycloaddition reaction with furan or N-arylation of secondary amides and amines. Due to the easy accessibility of the diaryliodonium salts, this kind of benzyne precursor is attracting

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• -alkynoates with N-bromosuccinimide (NBS) at rt [34], where those reactions proceed via radical spiro-cyclization and then radical 1,2-carboxyl group migration, were reported. On the other hand, diaryliodonium salts are very useful for the C-arylation of active CH groups, the O-arylation of OH groups, and the

• N-arylation of NH groups under metal-free conditions [35][36][37][38][39]. For example, treatment of arenecarboxylic acids and alkanecarboxylic acids with diaryliodonium salts and t-BuOK under toluene refluxing conditions provides the corresponding aryl carboxylates in good yields [40][41]. However

• , the O-arylation of 2-alkynoic acids, which are much more acidic than arenecarboxylic acids and alkanecarboxylic acids, and therefore, the conjugate bases of 2-alkynoic acids are much less nucleophilic than those of arenecarboxylic acids and alkanecarboxylic acids, was not studied. On the other hand

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• aryl diazonium salts to give the corresponding diaryl sulfide in high yields. Very recently, Noël and co-workers applied the above-mentioned concepts for the selective arylation of cysteine and cysteine-containing peptides in batch as well as in a photomicroreactor (Scheme 18) [49]. They were able to

Reactivity of bromoselenophenes in palladium-catalyzed direct arylations

• Aymen Skhiri,
• Ridha Ben Salem,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2017, 13, 2862–2868, doi:10.3762/bjoc.13.278

• employed to prepare 2-heteroarylated selenophenes; whereas, 2,5-dibromoselenophene generally gave 2,5-di(heteroarylated) selenophenes in high yields using both thiazole and thiophene derivatives. Moreover, sequential catalytic C2 heteroarylation, bromination, catalytic C5 arylation reactions allowed the

• recent years, the Pd-catalyzed arylation, via a C–H bond activation, of a broad range of heteroaromatics using aryl halides as reaction partners was demonstrated to be particularly effective for the preparation of bi(hetero)aryls [22][23][24][25][26][27][28][29][30][31]. Among the reported results, a few

• examined. The expected product 7 was obtained in a high yield of 81%. Thus, for Pd-catalyzed direct heteroarylations of 2-bromoselenophene, only the heteroarenes containing C–H bonds with low Gibbs free energies of activation [41] should be employed. By contrast, the direct arylation reactions with 2,5

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

• Sergey L. Deev,
• Alexander S. Paramonov,
• Tatyana S. Shestakova,
• Igor A. Khalymbadzha,
• Oleg N. Chupakhin,
• Julia O. Subbotina,
• Oleg S. Eltsov,
• Pavel A. Slepukhin,
• Vladimir L. Rusinov,
• Alexander S. Arseniev and
• Zakhar O. Shenkarev

Beilstein J. Org. Chem. 2017, 13, 2535–2548, doi:10.3762/bjoc.13.250

• Determining the accurate chemical structures of synthesized compounds is essential for biomedical studies and computer-assisted drug design. The unequivocal determination of N-adamantylation or N-arylation site(s) in nitrogen-rich heterocycles, characterized by a low density of hydrogen atoms, using NMR

• product structure were also found for N-arylation or N-alkylation with tert-butyl fragments in the series of 1,2,3-triazole [15][16], tetrazole [17][18][19][20], and purine [21] derivatives. Meanwhile, knowledge of the accurate chemical structures of N-substituted heterocycles is essential for biomedical

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• Göttingen, Germany 10.3762/bjoc.13.187 Abstract A new and efficient approach to five- and six-membered benzannelated sultams by intramolecular C-arylation of tertiary 1-(methoxycarbonyl)methanesulfonamides under palladium catalysis is described. In case of the α-toluenesulfonamide derivative, an unexpected

• formation of a 2,3-diarylindole was observed under the same conditions. Keywords: arylation; fused-ring systems; indole formation; palladium catalysis; sultams; Introduction The sulfonamide functional group stands out as one of the most important pharmacophores. At the same time, cyclic sulfonamides

• efficiently used for the preparation of ortho-functionalized anilines. This contribution deals with a new access to ring-annelated sultams by an intramolecular Pd(0)-catalyzed arylation of tertiary sulfonamides bearing an additional C–H acidic center (Scheme 1). From several potentially suitable electron

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

• ][75][76]. In view of this, chemists have introduced alternative energy sources like, microwave, sonication, mechanomilling, etc. [12][27][77]. Su and co-workers reported a copper-catalyzed arylation of anilines using arylboronic acid under high speed ball-milling conditions. Using 1.0 equiv of Cu(OAc

• palladium-catalyzed site selective mechanochemical dehydrogenative C–H/C–H arylation between oxime and arene moiety for the construction of Csp2–Csp2 bond with high para-selectivity of arene component via LAG. Using 10 mol % of Pd(OAc)2, 2.0 equiv of Na2S2O8 and 1.0 equiv TfOH the biaryls were synthesized

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• first palladium-catalyzed arylation of thiols was reported by Migita and co-workers in 1980 [5], and soon after Cristau and co-workers developed a nickel-catalyzed route for C–S cross-coupling reactions [6]. Other metals such as copper [7], cobalt [8], iron [9], rhodium [10], manganese [11], indium [12

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• ], Ullmann coupling [13][14], Buchwald–Hartwig amination [15] or N-alkylation of carbazole in the presence of alkali metal carbonates under MW irradiation [16]. In our case, the N-arylation was realized under phase transfer conditions using triethylbenzylammonium chloride (TEBA) as a catalyst [17][18

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• starting from an isoquinoline bearing an ester group at C-8. In a photoredox-catalyzed direct C–H arylation a 4-methoxyphenyl residue from a methoxyphenyldiazonium salt was introduced at C-1, and after ester hydrolysis intramolecular Friedel–Crafts acylation afforded menisporphine (2). In continuation of

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• , Russia Ivanovo State University of Chemistry and Technology, 7 Sheremetyevskii prosp., Ivanovo, 153000, Russia 10.3762/bjoc.13.152 Abstract The arylation of mono-, di- and tetra-meso-bromophenyl-substituted porphyrins with the heteroarenes containing “acidic” C–H bonds, such as benzoxazole

• our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins. Keywords: arylation; copper catalysis; heteroarenes; palladium catalysis; porphyrins; Introduction Porphyrins play an outstanding role in many

• ][11], Suzuki–Miyaura [12][13][14][15] and Stille couplings [16][17][18][19][20][21][22] were successfully applied for this purpose. Direct arylation and alkenylation are modern approaches for the formation of C–C bonds, and the application of these methodologies to porphyrins was widely studied by

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• ; photocatalysis; photo-Meerwein arylation–addition; Introduction Photoinduced multicomponent reactions are currently receiving remarkable attention [1]. Indeed, the possibility to obtain multiple-bond forming reactions under clean and mild conditions is nowadays one of the main targets of green chemistry

Synthesis of the heterocyclic core of the D-series GE2270

• Christophe Berini,
• Thibaut Martin,
• Pierrik Lassalas,
• Francis Marsais,
• Christine Baudequin and
• Christophe Hoarau

Beilstein J. Org. Chem. 2017, 13, 1407–1412, doi:10.3762/bjoc.13.137

• as readily available starting material. Keywords: antibiotic; bromination; BSC; C–H arylation; cross-coupling; Hantzsch synthesis; thiopeptide; Introduction Thiopeptide antibiotics are a class of peptide-derived macrocycles which contain many thiazole and thiazoline units, with almost 90 structures

• with a sophisticated tris-1,3-diazole, judiciously prepared through direct C–H arylation method, to synthesize the trithiazolylpyridine intermediate (Figure 1). The latter was then transformed to heterocycle core of GE2270 by adding a final bromination/Hantzsch sequence to build the last 2,4

• by using two developed innovative cross-coupling reactions, the palladium-catalyzed direct C–H (hetero)arylation of thiazole-4-carboxylate [21] and a palladium-catalyzed borylation-Suzuki coupling (BSC) 2-ketothiazole unit at 4-position as alternative to thiazolyltin intermediate [22]. Herein, an

Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS₂

• Jing Leng,
• Shi-Meng Wang and
• Hua-Li Qin

Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91

• turns red upon exposure to sunlight due to decomposition and formation of radical species [20]. Subsequently, the photodecomposition of diazonium salts by loss of nitrogen upon exposure to light has been utilized in organic synthesis for example to remove amino groups from anilines [21] or for arylation

Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

• Nikolay V. Lukashev,
• Gennadii A. Grabovyi,
• Dmitry A. Erzunov,
• Alexey V. Kazantsev,
• Gennadij V. Latyshev,
• Alexei D. Averin and
• Irina P. Beletskaya.

Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55

• arylation of aminocholanes has been described for the first time. While this Cu-catalyzed protocol provides high yields in reactions of aminocholanes with iodoarenes, Pd catalysis was found to be preferable for the reactions of aminocholanes with dichloroanthraquinones. UV–vis titration of bis(cholanylamino

• saturated with hydroxy groups was inconvenient for the syntheses of bis(polyoxamino) derivatives by Pd-catalyzed amination [34][35]. Direct metal-catalyzed arylation of aminocholanes has not yet been employed in the synthesis of cholane-based ligands. Here, we report a new and efficient synthesis of

• ability, chromophoric properties, and antitumor activity as well [40]. We compared several CuI-based catalytic systems in the arylation of amine 3b with 4-iodotoluene as a model substrate. We found out that the CuI/L-proline combination with K2CO3 led to the target aniline 4 in excellent yield (Scheme 3

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• the desired products 5a–j (Scheme 9). Noteworthy, the homogeneous catalysis requires only 1% of the XPhos-based palladium catalyst. A sonication bath was employed to prevent clogging and the reaction required a residence time of 15 min. Next, they turned their attention to the arylation of fluoro

• -donating or electron withdrawing ortho-substituents were tolerated (Scheme 14). A metal- and catalyst-free arylation procedure carried out under continuous-flow conditions was recently reported by Fagnoni [70]. This photochemical process allowed for the preparation of a wide range of synthetic targets by

• Ar–Csp3, Ar–Csp2 and Ar–Csp bond-forming reactions. The use of a photochemical flow reactor, consisting of a polyfluorinated tube reactor wrapped around a 500 W Hg lamp, allowed to overcome batch limitations paving the way for metal-free arylation reactions via phenyl cations. Derivatives 14a–g were

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• , the ability of the bulky silyl groups to alter the conformation of the glycosyl-donor ring can be used to control the selectivity. Suzuki and collaborators showed that the C-arylation reactions with the 3,4-O-di(tert-butyldiphenylsilyl)-protected acetate 56 led to the α-glycoside 58 with high

• thioglycoside 41. Regio- and stereoselective glycosylation using the superarmed thioglycoside donor 20. Superarmed donors used for C-arylation and the dependence of the size of the silylethers on the stereochemical outcome. β-Selective glucosylation with TIPS-protected glucosyl donors. The α-face is shielded by

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• /bjoc.12.275 Abstract The chromium-catalyzed enantioselective addition of carbo halides to carbonyl compounds is an important transformation in organic synthesis. However, the corresponding catalytic enantioselective arylation of ketones has not been reported to date. Herein, we report the first Cr

• -catalyzed enantioselective addition of aryl halides to both arylaliphatic and aliphatic ketones with high enantioselectivity in an intramolecular version, providing facile access to enantiopure tetrahydronaphthalen-1-ols and 2,3-dihydro-1H-inden-1-ols containing a tertiary alcohol. Keywords: arylation

• pharmaceutical study, finally leading to the discovery of the anticancer drug Eribulin [31][32][33][34][35]. However, to our knowledge, the Cr-catalyzed enantioselective arylation of carbonyl compounds has rarely been explored. On the other hand, most of the reactions focused on aldehyde components, while