Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• , 121, 123, 124 and 126 showed a better performance than IndII-SIMes in the RCM of 7 (Scheme 1), whereas the sulfur-containing catalysts 122 and 125 displayed lower activity. In more detail, 120, 121, 123 and 124 exhibited similar behavior, in spite of the different nature of aryl substituents, while

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• (depicted in Figure 2) is a transition where the HOMO is a non-bonding orbital (n) and π* an anti-bonding orbital. Both orbitals have different symmetries and this transition is observed for molecules with a heteroatom such as nitrogen, oxygen or sulfur which are carrying free electron pair. Most compounds

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

• halogenohydroxylation (Hal = I, Br) or addition–elemination of bromine (forming bromobutadienes) with high stereoselectivity [25][26]. Apart from that, reactions of sulfur containing allenes were studied in acidic media [27][28]. Despite promising results, there was no further research in this area. Based on our recent

• allenes 2. The main goals of this work were the investigation of reactions of sulfur-containing allenes 1 and 2 under electrophilic activation with Brønsted or Lewis (super)acids, and the study on cationic intermediates of these reactions by means of NMR and DFT calculations. Results and Discussion First

• 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

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• sulfur bridge is oxidized to the sulfoxide or sulfone. Hence, neither reductive nor oxidative conditions are compatible with the –CH2-S– bridge. An alternative strategy, that applies weakly acidic conditions is the condensation of aryl nitroso compounds with anilines. This Baeyer–Mills reaction was

• larger compared to the S-diazocine 3. The ethylene group in the 8-membered ring is disordered in two orientations with torsion angles of 47.9(1) and 37.7(1)°, which means that the overall molecule is more distorted in the C-diazocine than in the sulfur analogue. Conclusion The Baeyer–Mills reaction as

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• β-ketonitriles, arylhydrazines and aryl sulfonyl hydrazides as sulfur source [21]. The chemistry of iodine-catalyzed transformations has emerged as a greener, efficient and economical alternative to transition metals in organic synthesis [22][23][24]. However, the synthesis of selenium-containing 5

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

• aqueous solution is probably well recognized in the literature. Less corrosive and toxic effects and the lack of dangerous vapors make it safe to handle under normal conditions. MSA as a biodegradable chemical is decomposed within 28 days by living organisms and is part of the natural sulfur cycle. During

Photocatalyic Appel reaction enabled by copper-based complexes in continuous flow

• Clémentine Minozzi,
• Jean-Christophe Grenier-Petel,
• Shawn Parisien-Collette and
• Shawn K. Collins

Beilstein J. Org. Chem. 2018, 14, 2730–2736, doi:10.3762/bjoc.14.251

• corresponding dibromide could be formed from 1,9-nonadiol (6) in quantitative yield (99%, Table 1, entry 4). A sulfur-containing alcohol 7 was smoothly converted to its bromide in 99% yield (Table 1, entry 5). An allylic alcohol 8 having a cis-olefin underwent alcohol-to-halide conversion in 89% yield and was

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

• Takashi Go,
• Akane Morimatsu,
• Hiroaki Wasada,
• Genzoh Tanabe,
• Osamu Muraoka,
• Yoshiharu Sawada and
• Mitsuhiro Yoshimatsu

Beilstein J. Org. Chem. 2018, 14, 2722–2729, doi:10.3762/bjoc.14.250

• (diols). Seleno-Pummerer reactions of 3-selanylmethylpyrroles also proceeded via in situ generation of selenoxides, followed by a treatment with TBAH. Keywords: hydroamination; Pummerer reaction; pyrrole; pyrroloazepine; 1,7-sulfur shift; Introduction Pyrrolo- and indoloazepine skeletons are chemical

• the sulfur atom. Bis(trifluoro)acetate 16 resulted from the opening of the ring is hydrolysed by TBAH to yield diol 17. Conversely, sterically hindered double bonds of 14 are not easily accessible to the sulfonium ion; therefore, the Pummerer intermediate α-thio carbenium ion 18 is generated through

• oxidation proceeded to give the corresponding sulfoxide 5g in high yield. The sequential process, Pummerer reaction of 5g with TFAA, followed by treatment with TBAH to afford the 1,7-sulfur-shifted product 9g as crystals; however, the yield was relatively low. The final ytterbium-catalysed intramolecular

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• synthetic strategy. Usually, the allyl protecting group in N-Fmoc-Lys(Alloc)-OH is deprotected using Pd(PPh3)4 catalyst. However, the sulfur atom present in the cysteine moiety of the chelating core is known to poison palladium catalysts resulting in complete failure of the deprotection of the ε-amino allyl

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

• (His71) sidechain via π-stacking. For the thiophene-containing fragment 26 a π–π interaction of the sulfur with Phe195 can be observed. In vitro evaluation was performed using a combined PqsDE assay due to the aforementioned instability of 2-ABA-CoA which in this scenario is generated in situ from

Carbonylonium ions: the onium ions of the carbonyl group

• Daniel Blanco-Ania and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2018, 14, 2568–2571, doi:10.3762/bjoc.14.233

• replacement of carbon atoms by the heteroatoms oxygen, nitrogen and sulfur, respectively. Thus, “oxacarbenium ion” would denote a carbenium ion whose carbon atom is replaced by an oxygen atom, that is, an oxonium ion (3; Figure 2). Although if a coherent structure by formal subtraction of hydride from the

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• systems contain a heteroatom (e.g., oxygen, nitrogen, and sulfur, etc.) along with carbon atoms. The name of a heterocyclic propellane may be organized by prefixing aza, oxa, etc. Among various propellanes, nitrogen-containing compounds occupy a special place because they are present as core structural

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• tartrate. Subsequent oxidation of the primary alcohol to the aldehyde 15 was accomplished with the pyridine sulfur trioxide complex in 52% yield over two-steps [29]. The carbon atom at the acid oxidation state was installed by addition of trimethylsilyl cyanide to the aldehyde 15 in the presence of lithium

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• . Keywords: arenes; oxidation; photocatalysis; thiolation; visible light; Introduction The generation of carbon–sulfur bonds is an important task in organic synthesis, because of their abundance in target structures, such as natural products and drugs [1][2][3]. They are found in organic semiconductors

• reports on direct C–H functionalization using transition metals or metal free [37][38][39] conditions and different sources of sulfur, for example arylsulfonyl chlorides, sodium arylsulfinates, sulfinic acids and arylsulfonyl hydrazides have been reported (Scheme 1). However, the protocols require

• . When thiophenol was used as the sulfur source, diphenyl disulfide was obtained as a major side product, which in turn hindered the arylation process and resulted in several other oxidized products of thiophenol. So, the readily available diphenyl disulfide was added as the thiolating agent. Addition of

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• . Since these three calix[4]azulenes 3–5 are all-hydrocarbon compounds they differ significantly from the better-studied calix[4]arenes, which usually have some heteroatoms such as oxygen, nitrogen or sulfur in their structures. As a consequence, compounds 3–5 have solubility limitations. Furthermore, the

Microfluidic light-driven synthesis of tetracyclic molecular architectures

• Javier Mateos,
• Nicholas Meneghini,
• Marcella Bonchio,
• Nadia Marino,
• Tommaso Carofiglio,
• Xavier Companyó and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2018, 14, 2418–2424, doi:10.3762/bjoc.14.219

• , producing only traces of the expected sulfur-containing adduct 4i. As a matter of fact, compound 2e showed a high tendency to undergo a light-promoted [2 + 2] dimerization reaction, thus preventing the envisaged [4 + 2] cycloaddition pathway [13]. Next, the chromone scaffold 3a, which is a precursor of

The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• molybdopterin enzymes that also includes xanthine oxidoreductase and aldehyde oxidase [8]. Comparison of the pAO1 sequence with that of xanthine oxidoreductase identified ndhs, ndhm, and ndhl (initially designated ndhABC) as coding for three proteins: a 14.9 kDa subunit containing an iron–sulfur cluster, a 30

• two electrons produced are transferred through the iron–sulfur subunit to the FAD and thence to the final electron acceptor. L-6-Hydroxynicotine oxidase (LHNO) catalyzes the subsequent oxidation of L-6-hydroxynicotine to 6-hydroxy-N-methylmysomine [12]. Purified LHNO contains non-covalently bound FAD

Synthesis and post-functionalization of alternate-linked-meta-para-[2ⁿ.1ⁿ]thiacyclophanes

• Wout De Leger,
• Koen Adriaensen,
• Koen Robeyns,
• Luc Van Meervelt,
• Joice Thomas,
• Björn Meijers,
• Mario Smet and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2190–2197, doi:10.3762/bjoc.14.192

• ], less synthetic work has been performed on the synthesis of sulfur-linked cyclophanes with an alternating meta-para-bridge [26]. Herein we report a one-pot macrocyclization of meta-para-bridged thiacyclophanes by means of a substitution reaction between the biselectrophile 2,6-bis(chloromethyl)-4-tert

Synergistic electrodeposition of bilayer films and analysis by Raman spectroscopy

• Saadeldin E. T. Elmasly,
• Luca Guerrini,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Neil J. Findlay,
• Karen Faulds and
• Peter J. Skabara

Beilstein J. Org. Chem. 2018, 14, 2186–2189, doi:10.3762/bjoc.14.191

• has two consequences: (i) during the polymerisation of PEDTT, PEDOT remains doped and therefore conductive, allowing the polymerisation of EDTT to proceed; (ii) PEDTT can be de-doped within the electroactive window of PEDOT, meaning that the all-sulfur polymer can be successfully de-doped whilst the

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

• thiocyanate functional group, which is a precursor group to many sulfur-containing functional groups, as well as heterocycles such as thiazoles and isothiazoles. The imidazo[1,2-a]pyridine core is a particularly interesting drug-like structure, e.g., electron poor, polar, of low basicity, etc. The scope of

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• -cysteine has been proposed or discussed. Most plausibly, the attack of cysteine’s highly nucleophilic sulfur on GO’s epoxides did occur in this case [30][31], based on the changes observed in the IR spectrum of the product. The material’s structure would include free amino and carboxyl groups forming the

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• limitation encouraged for the development of organosulfur ligand based palladium(II) complexes by exploiting the strong donor properties of sulfur. Such complexes are found to be resistant to moisture, air and thermal stress/elevated temperatures and have been applied in catalysing Suzuki–Miyaura coupling

• reactions [32][33]. As it was elegantly reviewed by Singh and co-workers [33], these organosulfur ligands can be classified into pincer type (symmetrical and unsymmetrical), thioethers, thiourea-based ligands, sulfur-substituted NHCs, thiosemicarbazones and sulfated Schiff bases. Of the pincer ligands

• Cl− counter ion) were unsuccessful since the reaction of the SNS pincer ligand 19a with PdCl2(MeCN)2 led to the formation of N,S-Pd(II) 20a presumably due to the weak basicity of the sulfur atom. Gratifyingly, the problem was solved by treatment of the reaction mixture with the halide abstractor

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• cycloadduct was isolated in 37% yield. Keywords: hetero-Diels–Alder reactions; quinone dyes; quinones; sulfur heterocycles; thiochalcones; Introduction Hetero-Diels–Alder reactions are considered to be a powerful methodology widely explored for the synthesis of six-membered heterocycles [1][2] with numerous

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• sulfur-containing alkaloid 112. Initially, the substrates 110 were cyclized to spirodienone derivatives 111 in useful yields using PIFA (31) as source of electrophile in trifluoroethanol at room temperature (Scheme 40). Furthermore, synthesized compounds 111 were converted into the natural product

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• Mokgethwa B. Marakalala Edwin M. Mmutlane Henok H. Kinfe Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa 10.3762/bjoc.14.143 Abstract Sulfur-containing natural products are ubiquitous in nature, their most abundant source being marine organisms

• since sulfur, in the form of the sulfate ion, is the second most abundant anion in sea water after chloride. As part of natural products, sulfur can appear in a multitude of combinations and oxidation states: thiol, sulfide (acyclic or heterocyclic), disulfide, sulfoxide, sulfonate, thioaminal

• ; epoxide thiolysis; β-hydroxy sulfides; sulfur-containing natural products; Review 1. Introduction Organosulfur compounds are widely distributed in nature, with marine organisms being the richest sources of these, since sulfur, as the sulfate ion, is the second most abundant anion in sea water after