Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• addition of a trifluoromethyl radical to silyl enol ethers derived from ketones using the same reaction conditions (Scheme 12) [28]. 1.3 Oxidation reactions In 2015, Bissember and co-workers used the Sauvage catalyst to generate an α-amino radical, which was used to perform the synthesis of annulated

• ([Cu(I)]*/[Cu(II)]). Upon irradiation at 455 nm, the authors used this complex in ATRA reactions, with various ATRA reagents, including α-bromomalonates and benzyl bromides, in combination with a broad range of alkenes (allylamine, homoallyl alcohol, styrene derivatives, and silyl enol ethers). The

• )(dap)2]Cl. Trifluoromethyl methoxylation of styryl derivatives using [Cu(I)(dap)2]PF6. All redox potentials are reported vs SCE. Trifluoromethylation of silyl enol ethers. Synthesis of annulated heterocycles upon oxidation with the Sauvage catalyst. Oxoazidation of styrene derivatives using [Cu(dap)2

Synthesis of six-membered silacycles by borane-catalyzed double sila-Friedel–Crafts reaction

• Yafang Dong,
• Masahiko Sakai,
• Kazuto Fuji,
• Kohei Sekine and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2020, 16, 409–414, doi:10.3762/bjoc.16.39

• , Fukuoka 816-8580, Japan 10.3762/bjoc.16.39 Abstract We have developed a catalytic synthetic method to prepare phenoxasilins. A borane-catalyzed double sila-Friedel–Crafts reaction between amino group-containing diaryl ethers and dihydrosilanes can be used to prepare a variety of phenoxasilin derivatives

• ][6][7][8][9][10], and reagents [11][12][13][14]. Therefore, the development of new methods to construct silacyclic skeletons is highly desirable. These compounds are commonly synthesized upon the reaction of heteroatom-bridged dilithiated diaryl compounds, such as dilithiated diaryl ethers and

• benzosiloles [39]. We have also contributed to the synthesis of silafluorenes from biphenyls and dihydrosilanes using a borane-catalyzed double sila-Friedel–Crafts reaction [40][41]. Subsequently, we envisaged that the catalytic reaction between diaryl ethers and dihydrosilanes may be a useful protocol to

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• connecting the naphthyl rings [34][35][36]. In these compounds, the hydroxy groups are remained untouched or protected as the corresponding ethers or esters. We envisioned that the assembly of the binaphthyl-fused furan motif embedding the BINOL hydroxy groups into the polyaromatic scaffolds would lead to

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• 22 upon coordination with the carbonyl oxygen atom of the amide group. The complex 22 then coordinated to the acrylate product 23, which rearranged to 24, and the β-hydride elimination of 24 yielded the desired olefinated product 21. C–H olefination of phenolic ethers: Based on Ackermann and co

• olefination. C–H olefination of phenolic ethers. Decarboxylative acylation of acetanilides. Synthesis of fluorenone derivatives by intramolecular deoxygenative acylation of biaryl carboxylic acids. Synthesis of benzothiazoles via aerobic C–H thiolation. Synthesis of benzothiazoles via oxidant-free C–H

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• and the amine 4 (Scheme 3, part B). Attempts to improve the reactivity of potassium cyanate by adding crown ethers did not result in the formation of ureas as expected. Thus, five new amides 19–22 and 24 were obtained in yield range of 42–71% (19 42%; 20 53%; 21 58%; 22 53%; 24 71%). Mesomorphic

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• ) hydrogenolysis of benzyl ethers and benzylidene acetals over Pearlman’s catalyst [36] to furnish the desired pentasaccharide 1 in 49% overall yield (Scheme 4). The structure of compound 1 was unambiguously characterized by its NMR spectral analysis [signals at δ 5.37 (d, J = 2.0 Hz, H-1A), 5.29 (d, J = 3.5 Hz, H

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• compounds such as calixarenes, crown ethers and cyclodextrins, which can be used to form a stable inclusion complex with the drug, and improving the bioavailability of the drug [34][35]. Herein, we describe the results of the investigations of host–guest interactions between BALE and Q[8] in an aqueous

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• methanolysis, followed by Pd/C-catalyzed hydrogenolysis of the carboxybenzyl group and the benzyl ethers. Mannosides 4–6 were deprotected and purified using reversed-phase HPLC to obtain fully deprotected mannosides 10–12 (Figure 2). For the arabinomannosides 7–9, the acid-labile arabinose chain was cleaved

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• alternative approach to generate calcium release, where deforming an ion-binding site would render it less well-adapted to bind a guest. Photoisomerization of the azobenzene moiety has previously been successfully used to modulate the affinity of crown ethers [29], lariats [30], and foldamers [31] for various

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• towards chiral 1,4-dicarbonyls bearing tertiary and all-carbon quaternary stereocenters via oxidative cross coupling of 2-acylimidazoles 85 with silyl enol ethers 86 (Scheme 32). Chiral Rh complex 87 was exploited as a Lewis acid catalyst for the purpose of activating the substrate towards anodic

AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• employment of isoxazole nucleophiles in gold-catalyzed formal [3 + 2] cycloaddition reaction of ynamides [31][32], and zinc-catalyzed the reaction of ynol ethers [33], giving the respective multi-substituted pyrrole derivatives efficiently (Scheme 2a) [34][35]. The reaction proceeds via an α-imino gold

• . Reactions of ynamides or ynol ethers with isoxazoles by transition metal catalysis. Reactions of ynamide 4a with different isoxazoles 5, 7 and 8a. A gram-scale experiment. Mechanistic hypotheses for Ag-catalyzed reaction of ynamide 4a with aminoisoxazole 8a. Possible reaction routes of intermediate C

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• -coupling reactions was planned. Starting from 1-bromo-4-methoxynaphthalene (1), the Pd-catalyzed Suzuki coupling reaction with commercial boronic acids afforded the naphthyl and pyrenyl derived methyl ethers 2 and 3 in 78% and 87% yield, respectively (Scheme 1). For the synthesis of the anthryl derivative

• methyl ethers 2, 3 or 5 with BBr3 (1.1 equiv) in anhydrous CH2Cl2 (0 ºC→rt) allowed the transformation into the alcohol intermediates, which were treated with triflic anhydride (Tf2O) in dry dichloromethane to afford 9–11 in 59–79% yield. With the triflates 8–11 at hand, these were transformed into the

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• ]. Additionally, some complexes of mostly soft transition metals with ferrocenophane ligands could be identified. Herein, a main focus lies on complexes with ferrocenic thiacrown ethers as well as selenacrown ethers coordinating a transition metal occasionally inside the cavity of the ferrocenophane [78][79][80

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• extensively, the chemical design of the stabilizing donor ligand L2 has not been investigated as intensive. In general, carboxylic acid derivatives, ethers or free alcohols are utilized to stabilize the hypervalent iodine center by an oxygen–iodine bond or through dative oxygen–iodine interactions in (pseudo

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• trifluoromethylation of aryl/heterocyclic chlorides with the CF3 source TESCF3 (TES, triethylsilyl), which proceeded following a classical Pd(0)/Pd(II) catalytic cycle (Scheme 62). Also, the reaction tolerates a variety of functional groups, such as esters, amides, ethers, nitriles, etc., and therefore provides a new

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• template-directed self-assembly procedure via an intramolecular “CuAAC click” reaction in the presence of electron-rich bisnaphtho- or bisbenzo-24-crown-8 ethers. Afterwards, the triazole groups in the catenanes were methylated. The resulting triazolium macrocycle containing catenanes 17a (DN24C8) and 17b

• catenane 17b upon addition of base were less noticeable because of a weaker CT band in the case of a dibenzo-fused crown ether. Thus, the authors have proven that the movement of macrocyclic rings within catenanes can be controlled by switching the pH, and the bisnaphtho crown ethers can act either as

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• architectures. Historically, the most common components were dialkylammonium ions, as axles, and crown ethers, cyclodextrins, or cucurbiturils, as wheels [1]. With respect to the possible types of wheels, more recently, we have introduced the through-the-annulus threading of simple calix[6]arene hosts with

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• of diarylprolinol silyl ethers is highly diastereoselective and that the configuration of a newly created stereocenter at the α-position depends predominantly on the catalyst structure. The absolute configuration of chiral 1,2-diols has been unambiguously established based on electronic circular

• dichroism (ECD) and TD-DFT methods. Keywords: 1,2-diols; ECD; enamines; organocatalysis; porphyrins; silyl ethers of diarylprolinols; singlet oxygen; Introduction Carbonyl compounds are one of the most important building blocks in organic synthesis. As a consequence, there is a constant need for new

• separated by column chromatography. Photooxygenation of 3,4-diphenylbutanal (1) with chiral organocatalysts The highly enantioselective synthesis of 3,4-diphenylbutanal (1), according to the procedure developed by Melchiorre, requires the use of noncommercially available sterically bulky silyl ethers [16

Tautomerism as primary signaling mechanism in metal sensing: the case of amide group

• Vera Deneva,
• Georgi Dobrikov,
• Aurelien Crochet,
• Daniela Nedeltcheva,
• Katharina M. Fromm and
• Liudmil Antonov

Beilstein J. Org. Chem. 2019, 15, 1898–1906, doi:10.3762/bjoc.15.185

• alkali metal determination is still a challenge. In the case of alkaline earth metal ions, the reagents with reasonable selectivity are still not commonly accepted since they compete with transitional metal ions [4]. The discovery of crown ethers [5] and 3D-based ligands [6] unquestionably helped the

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• in general a solvent is not required, in solution environments the formation of products is assisted if the solubility of MX or RnM' is limited, as their precipitation helps shift the equilibrium toward the product side. If ethers are used as solvents, for example, the low solubility of MX can be

Novel macrocycles – and old ones doing new tricks

• Wei Jiang and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2019, 15, 1838–1839, doi:10.3762/bjoc.15.178

• 10.3762/bjoc.15.178 Keywords: macrocycles; supramolecular chemistry; Macrocycles [1] are the workhorses in supramolecular chemistry. Many basic supramolecular concepts have been developed through studying crown ethers, cryptands, podands and spherands in the 1970s and 1980s. For these contributions

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• , Institute of Molecular Sciences, UMR-CNRS 5255, 351 cours de la libération, Talence, 33405 Cedex, France 10.3762/bjoc.15.176 Abstract Four-component coupling reactions between xanthogenates, alkenes, CO, and sulfonyl oxime ethers were studied. In the presence of hexabutylditin, working as a propagating

• functionalities, have the potential for further elaboration. Keywords: CO; multicomponent reaction; radicals; sulfonyl oxime ethers; xanthogenates; Introduction Multicomponent reactions constitute a powerful and highly efficient tool in organic synthesis to build up intricate compounds from simple molecules in

• /acceptor type C1 synthons [6][7][8][9][10][11][12][13][14][15]. In this context, sulfonyl oxime ethers are powerful acceptors of type C1 synthon [8][16][17], which terminates the multicomponent reaction by a β-scission of RSO2 radicals [18][19][20]. Recently, one of us reported on a three-component radical

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• as tert-butyldiphenylsilyl ethers, individually transformed into 2-(3-hydroxypropyl)pyrrolidines by LiAlH4 reduction and deprotected. Diamines PF-00951966 (Scheme 18) belongs to a fluoroquinolone family of antibiotics which is substituted at C7 with a (3R)-3-[(1S)-2-cyano-1-(methylamino)ethyl

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• the silyl ethers. Unlike in the solution reaction, the HEBM isolated reaction products of β-CD were almost completely insoluble in water, while the γ-CD derivative was somehow soluble or solubilised, as seen in the UV–vis spectra. Both the β- and γ-CD derivatives showed high complexation affinity