Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• large positive charge in cations A, B. For dication Bh, different signals were detected for quaternary carbons C5 and C5', and vinyl carbons C4 and C4', etc., that, probably, indicates formation of two diastereomers (one meso-form and one pair of enantiomers) due to the stereogenic sulfur centers. In

• noting, that compounds 3a–h have strictly cis-configuration of SO2Ar group and a vinyl substituent at C2 carbon. It should be mentioned that palladium-catalyzed isomerization of such (arylsulfonyl)allenes 2 into trans-butadienes 3 was described recently [23]. Herein, we have developed a novel metal-free

• assignment of the cis-configuration of the ArSO2 group and the C3-substituent in compounds 3 and 4 was based on the low spin–spin interaction constant of 8.0–11.8 Hz between the vinyl protons in the 1H NMR spectrum (see Supporting Information File 1) and on comparison with the known trans-isomers of 3 [23

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• ) composite materials such as poly(1-vinyl-3-sulfo-1H-imidazolium chloride) grafted on MWCNT 100, poly(4-styrenesulfonic acid) grafted on MWCNT 101, and poly(4-vinyl-1-sulfo-pyridinium chloride) grafted on MWCNT 102 (CNT-PVSAIC, CNT-PSSA, and CNT-PVSAPC, respectively) was prepared (Scheme 18). Obtained

Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

• Ritabrata Datta and
• Subrata Ghosh

Beilstein J. Org. Chem. 2018, 14, 2708–2714, doi:10.3762/bjoc.14.248

• ether 7a in 92% yield. Two different paths can be invoked for metathesis of compound 7a. Metathesis initiation may occur by attack of the ruthenium alkylidene at the alkyne unit to produce the more substituted vinyl alkylidine intermediate 8a which may undergo concomitant ROM–RCM with the norbornene

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• polymeric materials. The products could not be separated by means of chromatography. Interestingly, however, the CM of (±)-19 with methyl vinyl ketone induced by G-2, HG-1 or HG-2, afforded a single derivative, monometathesised compound (±)-20 bearing the oxo group closest to the amide N-atom (Scheme 7

• the metallacyclobutane intermediate may reduce the reactivity of the olefinic bonds. Furthermore, the chelating ability of the amide heteroatoms is also assumed to be responsible for the chemodiscrimination of the vinyl groups. Namely, the chelating five-membered structure T1 is more favored than T2

• and, therefore, the vinyl group closest to the ring N-atom becomes more reactive in cross-metathesis (Figure 2). Similar chemodiscriminations of C–C double bonds were previously observed in the transformation of various alkenylated lactams or amino esters [16]. Lactams are known to be useful

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• mimetics More recently, Ji et al. published two classes of sulfonyladenosine inhibitors, more precisely the sulfamate/sulfamide inhibitors 5–9 and the vinyl sulfonamide inhibitors 10 and 11 (Figure 5). While the latter showed very low affinity for the protein, the former displayed Ki values between 88 nM

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• using various electrophiles such as alkyl halides [13], vinyl halides [14][15][16], aryl halides [17][18] and epoxides [19][20] in homogeneous solutions (Figure 1b). 1-2. Design of biomimetic and bioinspired B12 catalytic systems Schematic representations of B12 enzymes and enzyme-involving systems are

• (III) form of 1 has recently been found to catalyze atom transfer radical addition of alkyl halides to olefins (phenyl vinyl sulfone and acrylates) in the presence of NaBH4 [115]. In addition, a new light-driven method for generating acyl radicals from 2-S-pyridyl thioesters was developed through the

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• , compound 50 was treated with KHMDS in THF at −78 °C to produce enolate 51. Further, it was reacted with diphenyl chlorophosphate to generate vinyl phosphate 52, which was subjected to SM coupling in the presence of different 2-formylboronic acids 53 with the aid of the Pd(PPh3)4 catalyst to provide the

• adopting SM coupling and RCM as key steps. In this respect, SM coupling of sulfoximine 65 with potassium vinyltrifluoroborate (66) in the presence of a palladium catalyst produced vinyl sulfoximine derivative 67 (73%). Next, N-alkenylation of sulfoximine 67 was accomplished with Z-vinyl bromide (68) to

• CM by using Mo complex 6. In this regard, they assembled stilbene derivative 85 as an antitumor agent by a two-step strategy that involve catalytic CM and SM coupling. To this end, the Z-selective CM of a styrene derivative (e.g., 81) with vinyl-B(pin) 82 was realized in the presence of Mo complex 6

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• cyclization, since there is precedence of accessing medium-sized ring ethyl vinyl ethers when employing TiCl3/LiAlH4/NEt3 in DME instead of TiCl4/Zn/pyridine [23]. Direct reduction of ester 14 to the aldehyde proved to be surprisingly difficult with either DIBAL-H or LiAlH4, when the alkynyl side chain was in

• benzene partial structure. Preferred conformations of diastereomeric diols 18 and 19 including decisive NOESY correlations. Access to ketoester 14 that did not cyclize to the ethyl vinyl ether under McMurry conditions. Synthesis of the 1,3-cyclohexadiene-containing eunicellane-type [8.4.0]bicycle 18 by

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• carboxylation of aryl halides and pseudohalides using CO2 is an important reaction to yield benzoic acid derivatives. In 2009, Martin reported the Pd-catalyzed carboxylation of aryl bromides using ZnEt2 as the reductant [31]. In 2012, we first reported the Ni-catalyzed carboxylation of aryl chlorides and vinyl

• carboxylation of vinyl triflates 3. Co-catalyzed carboxylation of a sterically hindered aryl triflate 5. Optimization of the Co-catalyzed carboxylation of 7a. Scope of the reductive carboxylation of α,β-unsaturated nitriles 7. Scope of the carboxylation of α,β-unsaturated carboxamides 9. Optimization of the Co

Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal

• Antonio Arcadi,
• Sandro Cacchi,
• Giancarlo Fabrizi,
• Francesca Ghirga,
• Antonella Goggiamani,
• Antonia Iazzetti and
• Fabio Marinelli

Beilstein J. Org. Chem. 2018, 14, 2411–2417, doi:10.3762/bjoc.14.218

• -(o-aminophenyl)indole derivatives followed by further cyclization [19][20][21][22]. Our interest in this field led to the development of an original approach to 6-trifluoromethyl-12-aryl(vinyl)indolo[1,2-c]quinazolines 4 through sequential Pd-catalyzed reactions of bis(o-trifluoroacetamidophenyl

• )acetylene (1) with aryl or vinyl halides and triflates followed by cyclization reactions (Scheme 1) [19]. The reaction, which tolerates a variety of important functional groups, likely involves the formation of the indole intermediates 2 (through aminopalladation/reductive elimination) [20][21] followed by

• accomplished, without competitive formation of products derived from C-3 functionalization at the indole moiety. Synthesis of 6-trifluoromethyl-12-aryl(vinyl)indolo[1,2-c]quinazolines 4. Present and previously reported reactions starting from 5. DMFDMA: dimethylformamide dimethyl acetal. Two-step synthesis of

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• without decomposition. 2-Zn could be successfully transformed into a broad range of CF2CF2-containing molecules with good-to-excellent efficiency. Considering that our previous study found that the vinyl moiety in the coupling product could be a useful molecular building block [14][45], 2-Zn presented

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• , Whiteoak’s group reported a cobalt-catalyzed hydroarylation of terminal alkenes with amides 39 [78]. The reaction of vinyl ketones with amides provided alkylated product 40, whereas acrolein resulted in biologically useful azepinones in good yields (Scheme 26b). N-Pyrimidylindole is a highly reactive arene

• in cobalt-catalyzed C–H functionalizations. In this context, Li and co-workers developed an addition reaction of indoles 7 with activated alkenes using a cobalt(III) catalyst (Scheme 27) [79]. The reaction tolerated a wide range of alkenes including vinyl aldehyde, ketones, and divinyl ketones and a

• manner. Thus, Li et al. developed a cobalt-catalyzed hydroarylation of maleimides and maleate esters with arenes 48 (Scheme 30) [85]. A variety of arenes including indoles, 2-arylpyridines, 6-arylpurine, and vinyl pyridines were employed to give alkylated products 49 in good to moderate yields. As well

Evaluation of dispersion type metal···π arene interaction in arylbismuth compounds – an experimental and theoretical study

• Ana-Maria Preda,
• Małgorzata Krasowska,
• Lydia Wrobel,
• Philipp Kitschke,
• Phil C. Andrews,
• Jonathan G. MacLellan,
• Lutz Mertens,
• Marcus Korb,
• Tobias Rüffer,
• Heinrich Lang,
• Alexander A. Auer and
• Michael Mehring

Beilstein J. Org. Chem. 2018, 14, 2125–2145, doi:10.3762/bjoc.14.187

• is very similar to the monoclinic C2/c modification of Ph3Bi (1a) [41][42][43]. Additionally, short π···π distances were observed between one of the vinyl groups and the aryl ligand, with a distance from the centroid of the aromatic ring to the midpoint of the C═C double bond of 3.798 Å. The angle to

• the plane through the aryl ligand of the neighboring molecule amounts at 13.1° and thus a nearly linear arrangement between a bismuth atom, an aryl ligand, and the vinyl group with an angle of 171.8° is observed (Figure 4a). In 2a each Bi···π arene contact is accompanied by a πPh···πvinyl contact

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• -lactone fused cyclopentanone 10 in excellent yield (Scheme 4). Allylation and methylation both were occurred stereoselectively from the convex face to give α,α'-cis stereochemistry. The allyl derivative 10 was then subjected to cross metathesis reaction with ethyl vinyl ketone. Initially, the reaction

• performed using Grubbs’ 1st generation catalyst (3–20 mol %) was unsuccessful. Treatment of 10 with ethyl vinyl ketone using Grubbs’ 2nd generation catalyst (3 mol %) in the presence of CH2Cl2 furnished (E)-enone 11 in 77% yield as shown in Scheme 4. In the 1H NMR spectrum, 11 showed a signal at 6.13 ppm as

• , 1760, 1740, 1460 cm−1; HRMS (m/z): [M]+ calcd for C15H20O5, 280.1311; found, 280.1310. Methyl 1,1,3a-trimethyl-3,4-dioxo-5-((E)-4-oxohex-2-enyl)hexahydro-1H-cyclopenta[c]furan-5-carboxylate (11): To a solution of the compound 10 (110 mg, 0.327 mmol) in CH2Cl2 (0.8 mL) was added ethyl vinyl ketone (31

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• in biologically active molecules. This reaction was included due to the ability to introduce chirality into lead structures, something that is valuable in medicinal chemistry. The straightforward synthesis of isoxazoline 29a from the corresponding vinyl aldehyde is a perfect example of the potential

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• , some β-aryl/vinyl-substituted subporphyrins can be synthesized from aryl/vinyl borate and the corresponding β,β′-dihalosubporphyrins, which can be obtained by the treatment of β,β′-diborylsubporphyrins with NBS/NIS in the presence of a Cu(I) salt [36]. Recently, our group successfully prepared multiple

DFT calculations on the mechanism of copper-catalysed tandem arylation–cyclisation reactions of alkynes and diaryliodonium salts

• Tamás Károly Stenczel,
• Ádám Sinai,
• Zoltán Novák and
• András Stirling

Beilstein J. Org. Chem. 2018, 14, 1743–1749, doi:10.3762/bjoc.14.148

• ][37][38][39][40][41][42][43][44]. The mechanistic details of these cascade reactions are not clear as evidenced by the different mechanistic proposals (see, e.g., [18][30][40][44]). These mechanisms suggest the presence and existence of vinyl cation 7, alkynyl–Cu(III) 5, or alkenyl–Cu(III) complexes 6

• (Scheme 2, step 1). In the next step we compared the energetics of two different paths (paths A and B), to get insight into the order of the arylation and cyclisation steps. Additionally, the relevance of vinyl cation formation and the stereoselectivity were examined. The energy profiles start with the

• indicates the products oxazoline can be cis- or trans-isomers regarding the relative positions of the oxazoline oxygen and the incoming aryl group at the double bond. Formation of a vinyl cation would imply a non-stereospecific oxazoline formation. The calculations, however, revealed that its formation

The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

• Dominic Bernhard,
• Fabian Dietrich,
• Mariyam Fatima,
• Cristóbal Pérez,
• Hannes C. Gottschalk,
• Axel Wuttke,
• Ricardo A. Mata,
• Martin A. Suhm,
• Melanie Schnell and
• Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

• Göttingen, Germany Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Strasse 1, D-24118 Kiel, Germany 10.3762/bjoc.14.140 Abstract The structure of the isolated aggregate of phenyl vinyl ether and methanol is studied by combining a multi-spectroscopic approach and quantum

• -docking motifs via the phenyl and vinyl moieties, with an additional less populated OH∙∙∙P(phenyl)-bound isomer detected only by microwave spectroscopy. The correct prediction of the energetic order of the isomers using quantum-chemical calculations turns out to be challenging and succeeds with a

• -spectroscopic study to mixed aromatic olefinic ethers: in the case of phenyl vinyl ether (PVE), there is an ethenyl moiety replacing one of the phenyl rings compared to DPE. This introduces a localized π system along with the delocalized phenyl π system as hydrogen bond acceptor sites. Thereby, the complexity

Visible light-mediated difluoroalkylation of electron-deficient alkenes

• Vyacheslav I. Supranovich,
• Vitalij V. Levin,
• Marina I. Struchkova,
• Jinbo Hu and
• Alexander D. Dilman

Beilstein J. Org. Chem. 2018, 14, 1637–1641, doi:10.3762/bjoc.14.139

• were coupled with alkenes 2 (Figure 1). Esters and amides of acrylic acid, acrylonitrile, and vinyl phosphonate used in a small excess (1.2 equiv) were successfully fluoroalkylated. For vinyl(phenyl)sulfone, significant amounts of hydrodeiodination product RfH was formed, likely because of the

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• catalytic domino reactions. The group of Hayashi has reported in 2004 the first example of the transformation of a cyclic diaryl-λ3-iodane, for which both Ar–I bonds are used in a palladium cross-coupling reaction [56]. It relies on a double Heck reaction performed with methyl vinyl ketone in the presence

• –I motif (Scheme 22) [62]. Hence aryl- and alkyl-substituted terminal alkynes can be coupled via a Sonogashira reaction when PPh3 is used as ligand, while the use of diphenylphosphinoferrocenyl ligand (dppf) allows the Heck-type coupling of acrylates, vinyl ketones and electron-poor styrene

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• transition state C of the carbocobaltation step (Scheme 11), facilitating the further selective formation of the branched allylcobalt species D which could be converted into the thermodynamically more stable (E)-allylcobalt species E because of the flexible C(vinyl)–C(allyl) single bond. The generated

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• the efficient synthesis of benzotropone 11 in a good isolated yield (83%) via PdNPs@EDACs-catalyzed Heck coupling and intramolecular condensation of 2-bromobenzaldehyde (46) and methyl vinyl ketone (47) (Scheme 10) [58]. 2.2. Reactions of 4,5-benzotropone (11) 2.2.1. Reactions via the carbonyl group

• anhydride in benzene at 220 °C was reacted, [π2 + π8] cyclo-adduct 234 as a single product was isolated in 52% yield (Figure 9) [153][154]. The thermolysis of 230 in the presence of ethyl vinyl ether gave three volatile products 235–237 in GLC yields of 10%, 7%, and 15%, respectively (Figure 9) [154]. 5

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• , there are certain bonds like imine, oxime, hydrazone, orthoester, acetal, vinyl ether and polyketal [103] that are known to undergo hydrolysis at acidic pH, while being extremely stable during blood circulation. Therefore, acid-labile bonds could be hydrolyzed in the slightly acidic microenvironment and

Electrochemically modified Corey–Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene

• Fabiana Pandolfi,
• Isabella Chiarotto and
• Marta Feroci

Beilstein J. Org. Chem. 2018, 14, 891–899, doi:10.3762/bjoc.14.76

• dihalides or vinyl bromides using sodium in ammonia or strong bases [8]. Alternatively, the compounds are accessible by homologation of aldehydes following the Bestmann modification of the Seyferth–Gilbert reaction, using in situ generated dimethyl (diazomethyl)phosphonate [9][10]. Moreover, the aldehyde

• , temperature, working potential and amount of consumed charge [24]. Our group intensively investigated the electrochemical behavior of 1,1-dibromoalkenes by means of cyclic voltammetry and electrolyses [25] and we reported the selective synthesis of vinyl bromides through the cathodic reduction of 1,1

• the reaction with a Au cathode in acetonitrile (ACN) as the solvent and in the presence of an excess of acetic acid as the proton source. Under these conditions good yields of the vinyl bromides were obtained with preference of the Z-isomers (Scheme 3). We have now reconsidered this investigation in

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• Zhensheng Zhao Graham K. Murphy Department of Chemistry, University of Waterloo, 200 University Ave. W., Waterloo, N2L3G1, ON, Canada 10.3762/bjoc.14.67 Abstract Allyl and vinyl chlorides represent important structural motifs in organic chemistry. Herein is described the chemoselective and

• . Experimental evidence suggests that a radical mechanism is involved. Keywords: allene; chlorination; hypervalent iodine; synthetic methods; vinyl chloride; Introduction Organochlorine compounds are vital as polymer precursors [1], as pharmaceuticals [2][3] and agrochemicals [4][5][6] and as functional

• materials [7][8]. And as there is an abundance of chlorine-containing natural products, the synthesis of chlorinated functional groups, such as allyl- and vinyl chlorides, can represent challenging obstacles that practitioners of natural product synthesis must surmount [9][10][11][12]. More commonly, allyl