Synthesis and conformational preferences of short analogues of antifreeze glycopeptides (AFGP)

• Małgorzata Urbańczyk,
• Michał Jewgiński,
• Joanna Krzciuk-Gula,
• Jerzy Góra,
• Rafał Latajka and
• Norbert Sewald

Beilstein J. Org. Chem. 2019, 15, 1581–1591, doi:10.3762/bjoc.15.162

• resonance NMR spectra were recorded on a Bruker AMX600 spectrometer in deuterated dimethyl sulfoxide (DMSO-d6) at 298 K. Chemical shifts are given in ppm, relative to residual solvent signals (δH = 2.49 ppm, δC = 39.0 ppm). NMR spectral signal assignment and integration were carried out with Bruker TopSpin

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• -thiocarbamate. However, in this case only the isothiocyanate intermediate was obtained. Then, trimethylamine was applied in refluxing MeCN [95] or sodium hydroxide in dimethyl sulfoxide (DMSO) at 70 °C. In both cases only the isothiocyanate intermediate and phenol were observed by HPLC–MS but no formation of

Fluorine-containing substituents: metabolism of the α,α-difluoroethyl thioether motif

• Andrea Rodil,
• Alexandra M. Z. Slawin,
• Nawaf Al-Maharik,
• Ren Tomita and
• David O’Hagan

Beilstein J. Org. Chem. 2019, 15, 1441–1447, doi:10.3762/bjoc.15.144

• -difluoroethyl thioether motif to explore further its potential as a substituent for bioactives discovery chemistry. Incubation of two aryl–SCF2CH3 ethers with the model yeast organism Cunninghamella elegans, indicates that the sulfur of the thioether is rapidly converted to the corresponding sulfoxide, and then

• significantly more slowly to the sulfone. When the substrate was (p-OMe)PhSCF2CH3, then the resultant (demethylated) phenol sulfoxide had an enantiomeric excess of 60%, and when the substrate was the β-substituted-SCF2CH3 naphthalene, then the enantiomeric excess of the resultant sulfoxide was 54%. There was no

• compounds that are of commercial significance [8][9][10]. Metabolism studies in both of these cases show that the major metabolites are their corresponding sulfoxides (Ar–S(O)CF3) and sulfones (Ar–S(O)2CF3) [8][9]. Indeed, in the case of the insecticide fipronil it is actually the sulfoxide (Ar–S(O)CF3

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• 1,1’-bis(diphenylphosphino)ferrocene (dppf) from Frontier Scientific. Absolute tetrahydrofuran, dichloromethane, and toluene were provided from Sigma-Aldrich and purified using a Büchi MB SPS-800. Dimethyl sulfoxide, acetonitrile, and acetone were purchased from Merck and Sigma-Aldrich, purified, and

• -b:4,5-b’]dithiophene (2). To a stirred solution of 3,3'-diiodo-2,2'-bithiophene (5, 200 mg, 0.48 mmol) and selenourea (118 mg, 0.96 mmol) in dry dimethyl sulfoxide (1.5 mL) at rt was added copper(I) oxide nanoparticles (4 mg, 48 µmol, 10 mol %) followed by potassium hydroxide (54 mg, 0.96 mmol). The

• sulfoxide (0.8 mL) under argon at rt was added copper oxide nanoparticles (1.2 mg, 10 mol %) followed by potassium hydroxide (26 mg, 0.46 mmol). The mixture was heated at 80 °C for 18 hours, cooled to rt, and a 1:1 mixture of dichloromethane/water was added. The combined organic extracts were collected

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• by the coordination of β-ketosulfones through the oxygen atom of the sulfonyl group with Ni. For example, sulfoxide complexes with O-coordination of the corresponding ligands are widely known [57]. Although the donor properties of sulfones are lower than those of sulfoxides. Results and Discussion

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• several additional experiments, the authors propose a tentative mechanism based on a Pummerer-type rearrangement. First, dimethyl sulfoxide (3) and carboxylic acid 1 combine to render ester 5 that decomposes, giving a thionium derivative of DMSO (6, Scheme 1). This electrophilic derivative would react

• with the nucleophilic aromatic ring in a Friedel–Crafts alkylation process, thus incorporating the carbon atom in a formal C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling. Finally, an oxidation of sulfide 7 to sulfoxide 8 and the subsequent attack of amide 2 with cleavage of the C–S bond and formation

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• = |2.59| cm−1 were determined [13]. UV–vis spectroscopy All new compounds were further investigated by electronic absorption spectroscopy. The electronic absorption spectra were recorded in acetonitrile (1, 2 and 5–9) or dimethyl sulfoxide (3, 4) solution in the 190 to 1200 nm spectral range. Figure 11

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives

• Peng Li,
• Yongqi Wu,
• Tingting Zhang,
• Chen Ma,
• Ziyun Lin,
• Gang Li and
• Haihong Huang

Beilstein J. Org. Chem. 2019, 15, 703–709, doi:10.3762/bjoc.15.65

• from 2’-chloroacetophenone as the starting material through treatment with carbon disulfide in the presence of sodium hydride [23], followed by alkylation using iodoethane according to the literature procedures [13][16][17][19]. The oxidation of 1 with 1.2 or 5 equiv of H2O2 yielded ethyl sulfoxide 2

• and ethyl sulfone 3, respectively (Scheme 2). With the substrates including sulfide, sulfoxide and sulfone in hand, we screened various solvents with compounds 1a, 2a, 3a and 1-benzylpiperazine as the model substrates and the results are summarized in Table 1. No target compound 4a was obtained at

• , thereby providing opportunities for discovering more active compounds for medicinal chemistry research. Representative strategies for the synthesis of N-substituted 2-aminobenzothiopyranones. The synthesis of sulfide 1, sulfoxide 2, and sulfone 3. Scope of the synthesis of versatile 2

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• chloroform whereas in dimethyl sulfoxide and water solutions, mixtures of α- and β-anomers are observed, with α/β ratio being 1:1.7 and 1:1.5, respectively. Moreover, mutarotation of the tosylate 23 is very fast in aqueous basic solution, being almost instantaneous in aqueous 2 M Na2CO3 as emphasized by the

Study on the regioselectivity of the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide

• Pedro N. Batalha,
• Luana da S. M. Forezi,
• Maria Clara R. Freitas,
• Nathalia M. de C. Tolentino,
• Ednilsom Orestes,
• José Walkimar de M. Carneiro,
• Fernanda da C. S. Boechat and
• Maria Cecília B. V. de Souza

Beilstein J. Org. Chem. 2019, 15, 388–400, doi:10.3762/bjoc.15.35

• . Procedure for the preparation of N-benzyl-1-ethyl-4-oxo-1,4-dihydroquinoline-3-carboxamide (7) In a round bottom flask, 1.0 g (3,6 mmol) of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide (5), 1.4 g (10.1 mmol) of potassium carbonate and 10.0 mL of dimethyl sulfoxide (DMSO) were added and stirred at room

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• ; sulfoxide; thiol-free; Introduction Throughout the years, several strategies have been developed to build up organic compounds bearing a sulfide moiety [1][2]. Often, thiols (or the corresponding thiolate anions) are employed as nucleophilic sulfur reagents in order to react with a suitable electrophile [3

• chromatography (petroleum ether/EtOAc 9:1) a 68% isolated yield was obtained for the S-allyl-β-ketosulfide 2h. The obtained β-ketosulfides can be chemoselectively converted into the corresponding sulfoxide/sulfone derivative [47][48]. It is well known that β-ketosulfoxides and β-ketosulfones are valuable

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• transformations include the carboxylation of a (trimethylsilylmethyl)cyclopropene in the presence of a fluoride promoter [22], and also the addition of electrophiles to (lithiomethyl)cyclopropenes generated by lithiation of the corresponding methylcyclopropenylsulfone [23] or -sulfoxide [24]. More recently, the

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• of tetrazine), the temporal progress of substrate 2 and product 3 could be followed directly (Figure S5, Supporting Information File 1). Unfortunately, no reaction intermediates were detected. Using a lower amount of solvent (0.2 mmol of tetrazine in 10 mL of dimethyl sulfoxide) has the downside that

• measurement. Then, spectra were measured with only one scan in defined intervals without ejecting the sample tube from the instrument. Reaction R1 (acetone, untagged substrate, L-proline, rt) Experiment 1 NMR A solution of L-proline in deuterated dimethyl sulfoxide (1.206 mL, 0.58 mmol/L, 0.0007 mmol, 0.05

• equiv) was added to commercially available 3,6-di(2-pyridyl)-1,2,4,5-tetrazine (2, 3.3 mg, 0.014 mmol, 1.0 equiv). Additional 1.764 mL of deuterated dimethyl sulfoxide were added. The concentration was chosen sufficiently low to ensure that all components were fully dissolved at room temperature. A

A simple and effective preparation of quercetin pentamethyl ether from quercetin

• Jin Tatsuzaki,
• Tomohiko Ohwada,
• Yuko Otani,
• Reiko Inagi and
• Tsutomu Ishikawa

Beilstein J. Org. Chem. 2018, 14, 3112–3121, doi:10.3762/bjoc.14.291

• carbonyl group at 4 position. Thus, it is generally difficult to synthesize the pentamethyl ether efficiently by conventional methylation. Here, we describe a simple and effective per-O-methylation of quercetin with dimethyl sulfate in potassium (or sodium) hydroxide/dimethyl sulfoxide at room temperature

• . This indicates the difficult methylation of the OH group at 5 position. Therefore, we consider to apply the more strongly basic system of potassium hydroxide (KOH) and dimethyl sulfoxide (DMSO). To a suspension of powdered KOH (9 equiv) in DMSO were successively added quercetin (2) and Me2SO4 (8 equiv

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

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

• stepwise procedure succeeded to give 7-phenylselenodiol 10a in 91% yield. Next, we performed the Pummerer reaction of N-β-methallyl sulfoxide 5b in order to clarify the substituent effects on the N-alkenyl groups. Surprisingly, the reaction of 5b afforded the intramolecular cyclised pyrroloazepine 11b. The

• low. These products were confirmed by X-ray spectra and/or single-crystal X-ray diffraction patterns. The unique S-shift reactions in the formation of either pyrrolo[3,2-c]azepines or diols proceeded according to the mechanism we proposed, which is depicted in Scheme 4. Sulfoxide 13 is activated by

• 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

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• trigonal prismatic cages 3a and 3b. The heterometallic prismatic cages were isolated as nitrate complexes in good yields. The isolated cages are soluble in methanol, acetonitrile, acetone, nitromethane, dimethyl sulfoxide and partially soluble in chloroform and dichloromethane. The formation of these cages

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

• in aqueous solutions is higher than their colloidal stability in typical polar aprotic solvents such as dimethyl sulfoxide [32][33]. However, some researchers have reported successful attempts at functionalizing GO or RGO in organic solvent [34][35][36][37]. Surprisingly, some examples in which GO or

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• ) for all CSP analogs. 2 µL of 1 mM solution of CSP analogs in dimethyl sulfoxide (DMSO) were added in triplicate to a clear 96-well microtiter plate. 2 µL of 20 µM solution of CSP1 were added in triplicate and served as the positive control for the group I strain (D39pcomX::lacZ), while 2 µL of 100 µM

Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

• Rakesh Puttreddy,
• Ngong Kodiah Beyeh,
• S. Maryamdokht Taimoory,
• Daniel Meister,
• John F. Trant and
• Kari Rissanen

Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146

• cavity C–H···π(host) interactions that win in the presence of most other guests. Therefore, investigating H–G complexes relying on N–O···(H–O)host HBs is challenging especially in HB competitive solvents such as methanol and dimethyl sulfoxide (DMSO). In reports from our lab, we disclosed that the π

• -d6, methanol/chloroform (CD3OD/CDCl3) 1:1 v/v and methanol/dimethyl sulfoxide (CD3OD/DMSO-d6) 9:1 v/v. The above solvent mixtures were chosen due to the poor solubility of some of the guests in pure methanol. DMSO is known to be an extremely HB competitive solvent and thus prevents the clear

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

• 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

• , sulfide (acyclic or heterocyclic), disulfide, sulfoxide, sulfonate, thioaminal, hemithioacetal, various thioesters, thiocarbamate and isothiocyanate [3]. The three simplest sulfur-containing natural products are perhaps, (E)-2-butene-1-thiol (1), the principal ingredient of the repulsively malodorous

• single thiol was employed. In a subsequent one pot procedure, addition of tert-butyl hydroperoxide to the reaction mixture afforded β-hydroxy sulfoxide 32 in good yields. In a similar fashion, Su et al. reported first the Ga(OTf)3 catalyzed regio- and stereoselective ring opening of epoxides 23 with

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• in the synthesis of 4’-thionucleosides as well as normal “4’-oxy” nucleosides. However, for reasons which will be described later, we decided to develop an alternative method to build the glycosyl bond of 4’-thionucleosides by using a direct coupling of a 4-thiosugar sulfoxide and a silylated base

• sila-Pummerer reaction by Kita, it was plausible that the reaction proceeded via the formation of sulfenium ion 14 which was formed by β-elimination of silylated sulfoxide 13. The 4’-thioDMDC derivative 15 was deprotected and the resulting anomeric mixture was separated to furnish 4’-thioDMDC (3) and

• derivative, 2-dimethoxybenzoate 20 was prepared from tribenzylated ribose 16. Introduction of a dimethoxybenzoyl (DMBz) group at the 2-position and diastereoselective formation of sulfoxide 20, favored in Pummerer-type glycosylation reactions and cases where the approach of the nucleophile is restricted

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• then oxidized to the sulfoxide G by iodosoarene C via the postulated activated sulfoxide F, releasing one equivalent of aryl iodide 2. A Chugaev-type elimination yields the olefin H, which finally affords acrylamidine 35 via Heck coupling with the iodoarene 2 with 50% AE (for R1 = H, R2 = Bn, Ar1 = Ar2

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• -butyl methyl ether the hydrogen bonds dominate, the variation in stabilization of the different substituted azobenzenes in dimethyl sulfoxide can be rationalized by London dispersion interactions. These findings were supported by conformational analysis and DFT computations and reveal low-energy London

• ,-trimethylhexanoylamino)benzyl]azobenzene (4, Table 1, entry 1), expressed in the longest half-lives τ. However, in the highly polar solvent dimethyl sulfoxide (DMSO) all azoamides (4, 5, Table 1, entries 1 and 2) as well as the azocarbamate 6 (Table 1, entry 3) showed very similar isomerization rates. Additionally