Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• underlying idea behind the latter application is that protonation of the leaving group by a general acid is not needed with 5´-thiosubstituted analogs, since the sulfide ion is a much better leaving group than the alkoxide ion. Most extensively used thiosubstitution, however, is replacement of either one of

• state resembles the transition of ribonucleoside 3´-aryl phosphates rather than 3´-alkyl phosphates, which is expected on the basis of 105-fold lower basicity of sulfide ions compared to alkoxide ions. The effect of non-bridging thiosubstitution on the cleavage rate is modest compared to the bridging

• conditions. The hydrogen sulfide ion is 105 times less basic than the hydroxide ion and, hence, able to compete with the sugar oxyanions as a leaving group upon breakdown of the thiophosphorane intermediate (the bond energies of P–O and P–S bonds are 86 kcal mol−1 and 55 kcal mol−1, respectively [103

The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives

• Shunsuke Kuribayashi,
• Tomoyuki Kurioka,
• Shinsuke Inagi,
• Ho-Jung Lu,
• Biing-Jiun Uang and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2018, 14, 389–396, doi:10.3762/bjoc.14.27

• well as 2-(tert-butoxycarbonyl)oxy-3,3,3-trifluoropropyl phenyl sulfide [29]. Conclusion In summary, we have achieved the regioselective anodic fluorination of various S-alkyl and S-substituted alkyl benzothioate derivatives in Et4NF·4HF/CH2Cl2 and a fluorine atom was selectively introduced in the α

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• -alkylation compound 7e was obtained instead of the desired furan (Table 1, entry 5). It is possible to consider that the d orbitals of the sulfur atom in a sulfide group could possibly stabilize the adjacent carbanion [73][74]. To expand the scope of substituted N,S-acetals that could provide the desired

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

• apply cysteine-containing glutathione for the reaction with a series of highly functionalized alkenes to form the respective sulfide adducts with yields up to 99%. This concept attracted attention from different fields of chemistry. Boyer and co-workers for example applied the redox mediator accelerated

• β-ketosulfoxide. No additional sacrificial substrates are needed in order to regenerate the photocatalyst or for the oxidation of the sulfenyl intermediate to the respective sulfoxide moiety. Hydrogen peroxide, which is generated as a byproduct, directly is consumed by oxidizing the sulfide to the

• and were able to couple a series of electron-rich and electron-poor styrene derivatives with aromatic and also long-chain aliphatic thiols to the respective sulfoxides, after aerobic oxidation (Scheme 15a). They describe a photocatalyzed thiol–ene reaction mechanism, where the sulfide-adduct is

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• ]indole 3 in 66% yield. Then, the chemical modification of the phosphorus atom of 3 was carried out and the results are shown in Scheme 2. The treatment of 3 with hydrogen peroxide, elemental sulfur, and elemental selenium afforded the corresponding phosphine oxide 4, sulfide 5, and selenide 6

• , respectively. The reaction of 3 with methyl triflate afforded phospholium triflate 7. Phosphole 3 was treated with chloro(dimethyl sulfide)gold in CH2Cl2, resulting in P-complexation and thus affording the gold complex 8. The borane complex 9 was readily prepared from 3 by treating with borane in THF. The

• = 75%) was high, comparable to that of phosphole and indole-fused pentacyclic heteroacene (Ф = 70%) [35]. On the other hand, a low fluorescence intensity was observed for phosphine sulfide 5 and selenide 6 (Ф = 1% and 0.3%, respectively). Quenching of fluorescence emission due to a soft sulfur

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• product [30] (Scheme 6). The analogous reaction with phenyl vinyl sulfide (22) gave the expected cyclobutane 23 exclusively. However, in the absence of ZnCl2, a mixture of 23 and 3,4-dihydro-2H-pyran 24 was obtained, with the latter compound formed through a competitive hetero-Diels–Alder reaction [30

• aromatic systems. Miscellaneous reactions The oxidation of E-1a with H2O2 in acetonitrile gave oxirane 101, which subsequently was used for reactions with diverse nucleophiles [80] (Scheme 32). Upon treatment with diheptyl sulfide, 101 was transformed into ethoxalyl cyanide (102) [81]. The aziridination of

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• oximes 95, if the elimination of dimethyl sulfide from 94 proceeds faster than the cyclization. The cyclization/elimination selectivity was found be highly dependent on the nature of substituents in ylide 92. Only when R3 was an acyl or phenacyl group, exclusive formation of isoxazoline products 93 was

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• to afford the corresponding glycosyl amide 26. Two possible reaction pathways have been proposed for this dehydrative glycosylation (Scheme 7) [37]. Upon mixing diphenyl sulfoxide and triflic anhydride, diphenyl sulfide bis(triflate) (27) is formed in situ (Scheme 7a). In pathway 1, hemiacetal 28

• could attack the sulfonium center of diphenyl sulfide bis(triflate) (27) to give the glycosyl oxosulfonium intermediate 29, which subsequently glycosylated the acceptor to yield the product 30 (Scheme 7b). Alternatively, in pathway 2, hemiacetal 28 could attack the sulfonyl center of diphenyl sulfide

• [19] found that with BSP/Tf2O promoter, the glycosylation of donor 72 and acceptor 74 gave a moderate yield of 44% (α:β = 2:1) of the desired product 75 (Scheme 14). This was attributed to the formation of (N-piperidino)phenyl(S-thioethyl)sulfide triflate (73) from the reaction of BSP/Tf2O with the

A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

• Grzegorz Mlostoń,
• Paulina Pipiak,
• Róża Hamera-Fałdyga and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185

• hydrogen chloride and hydrogen sulfide streams through the ethanolic solution at 0–5 °C (ice bath cooling) [33]. In analogy to 1a, hetaryl thioketones 1b,d–g were prepared from the corresponding ketones [34] by treatment with L.R. in toluene solution upon irradiation with microwaves over 2 min [32

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• -pot process. Based on our understanding of organosulfur chemistry [20][21][22], we report herein a simple, metal-free method for the formation of benzothiophenes using an intramolecular addition of a sulfur atom (originated from a sulfide) to the electron-deficient allene moiety generated in situ by a

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

• and Ni/RGO-60) were also tested (Table 1). All reactions were carried out under a N2 atmosphere to avoid oxidative dimerization of thiols to disulfide [50]. Solvent optimization was started with water (Table 1, entry 1) followed by toluene (Table 1, entry 2) and isolating diaryl sulfide only 6–8

Phenylsilane as an effective desulfinylation reagent

• Wanda H. Midura,
• Aneta Rzewnicka and
• Jerzy A. Krysiak

Beilstein J. Org. Chem. 2017, 13, 1513–1517, doi:10.3762/bjoc.13.150

• sulfide substituents, under these conditions, reduction of the carbonyl group occurred leading to the corresponding alcohols (18 [25], 22) as the only products in high yield. It means that attack on sulfur is not connected with the presence of a C–S bond but a sulfinyl substituent is required. In a former

Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones

• Adesh Kumar Singh,
• Varsha Tiwari,
• Kunj Bihari Mishra,
• Surabhi Gupta and
• Jeyakumar Kandasamy

Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113

• , oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide. Keywords: monosaccharides; oxidation; sulfones; sulfoxides; thioglycosides; urea–hydrogen peroxide; Introduction Organosulfur compounds such as sulfides, sulfoxides and sulfones are useful intermediates

• further investigated the suitable conditions for the direct oxidation of sulfide to sulfone using UHP in acetic acid. For this, we have tried the reactions with an increased amount of UHP and elevated temperature (Table 1, entries 10–12). It was observed that with 1.5 to 2.0 equiv of UHP at 80 °C, the

• reaction yields a mixture of sulfoxide 1a and sulfone 1b (Table 1, entries 10–11) in different ratio. However, by increasing the amount of UHP to 2.5 equiv, sulfide 1 is fully converted to the corresponding sulfone 1b in an excellent yield, i.e., 93% in 10 h at 80 °C (Table 1, entry 12). With optimized

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

• (Table 1, entries 7 and 8). Unfortunately, under the applied conditions, the chemoselectivity of the reaction was poor, affording a mixture of unexpected diphenyl sulfide (4a) and diphenyl polysulfides (5a) as byproducts. Thus, a study to optimize the reaction conditions with regard to chemoselectivity

• of a carbon sulfide [11]. The active radical intermediate III can transform into three types of products through different pathways. Firstly, diaryl disulfide 3 is obtained through a dimerization of radical intermediates III, whereas the reaction of radical III with phenyl radical I is leading to

• byproduct 4. Finally, radical III can react with various equivalents of CS2 with release of carbon sulfide to generate aryl-polythio radicals IV and V. The combination of the latter intermediates with radical I then finally affords polysulfides 5. To demonstrate the scope of the reaction, a series of

Conjecture and hypothesis: The importance of reality checks

• David Deamer

Beilstein J. Org. Chem. 2017, 13, 620–624, doi:10.3762/bjoc.13.60

• through the ocean floor where the mineral solutes come out of solution to form characteristic chimneys that emit a black smoke of precipitated metal sulfide particles. A second type of hydrothermal vent was discovered in 2001 [11] that does not depend on volcanism. Instead they form when seawater reacts

• vent conditions by injecting a solution of potassium phosphate, sodium silicate and sodium sulfide (pH 11) into a second solution of ferrous chloride, sodium bicarbonate and nickel chloride (pH 5). The aim was to determine whether carbon dioxide (present as 10 mM sodium bicarbonate) can be reduced

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• intramolecular sulfide and disulfide compounds, so that it is difficult to isolate aryl thiols as final product. For example, many reactions use aryl thiols as active intermediates to form benzothiazoles from aryl halides [95][96]. The first report of a transition-metal-catalyzed synthesis of aryl thiol appeared

• bromides bearing electron-withdrawing groups to the corresponding aryl thiols in good to excellent yields (Scheme 62) [105]. During the reaction, neither disulfide nor sulfide was formed. A simple investigation showed that aryl halides may first couple with 1,2-ethanedithiol and the coupled product was

Fast and efficient synthesis of microporous polymer nanomembranes via light-induced click reaction

• Qi An,
• Youssef Hassan,
• Xiaotong Yan,
• Peter Krolla-Sidenstein,
• Tawheed Mohammed,
• Mathias Lang,
• Stefan Bräse and
• Manuel Tsotsalas

Beilstein J. Org. Chem. 2017, 13, 558–563, doi:10.3762/bjoc.13.54

• radicals. Additional thiol moieties can undergo hydrogen transfer to the vinyl radical leading to thiyl radicals and vinyl sulfides. The vinyl sulfides can then undergo a thiol–ene coupling (TEC) reaction, leading to bis-sulfide species. TYC has been used for surface modification [21][22

New syntheses of (±)-tashiromine and (±)-epitashiromine via enaminone intermediates

• Darren L. Riley,
• Joseph P. Michael and
• Charles B. de Koning

Beilstein J. Org. Chem. 2016, 12, 2609–2613, doi:10.3762/bjoc.12.256

• Eschenmoser sulfide contraction of thiolactams with α-halocarbonyl compounds [24][25], which was originally described by Eschenmoser and co-workers in 1970–1971 [26][27]. We were interested to examine the impact of different electron-withdrawing substituents at what would become the 8-position of the

Development of a continuous process for α-thio-β-chloroacrylamide synthesis with enhanced control of a cascade transformation

• Olga C. Dennehy,
• Valérie M. Y. Cacheux,
• Benjamin J. Deadman,
• Denis Lynch,
• Stuart G. Collins,
• Humphrey A. Moynihan and
• Anita R. Maguire

Beilstein J. Org. Chem. 2016, 12, 2511–2522, doi:10.3762/bjoc.12.246

• compounds has been well documented [3]. The predominant site of reactivity is at the electrophilic β-carbon, which results from the combined influence of the amide and chloro substituents, mitigating the electron-donating effect of the sulfide moiety. Nucleophilic substitution [4], Diels–Alder reactions [5

• ] and 1,3-dipolar cycloadditions [6][7][8][9], and oxidation of the sulfide group [10][11][12] are among a wide array of transformations which have been successfully applied to these compounds (Scheme 1). In order to fully exploit the synthetic potential of these β-chloroacrylamides, however, a means of

DNA functionalization by dynamic chemistry

• Zeynep Kanlidere,
• Oleg Jochim,
• Marta Cal and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2016, 12, 2136–2144, doi:10.3762/bjoc.12.203

• potassium bromide substitution under overall retention of configuration due to double inversion. Next, the subsequent reduction of carboxylic acid 6 to alcohol 7 was achieved by borane dimethyl sulfide (BMS) under dry conditions. The reaction between alcohol 7 and 3-mercaptopropanenitrile (8) resulted in

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• ambient atmosphere was then stirred at room temp for 16 h. Then, sodium sulfide nonahydrate (960 mg, 4.00 mmol) and potassium hydroxide (224 mg, 4.00 mmol) were added and the reaction mixture in the closed vessel was heated at 120 °C in the microwave cavity for 30 min. After cooling to room temperature

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• improved to α:β = 10:1. In addition, 25 was afforded in 67% with excellent α-selectivity (α:β = 10:1) with the addition of dimethyl sulfide (DMS) (Table 2, entry 6). However, the basic additive 2,4,6-tri-tert-butylpyridine (TTBP) produced 25 with poor selectivity (52%, α:β = 2:1, Table 2, entry 7

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• gel the solvent was evaporated to give a colorless oil. 3-Hexyl-1-phenylphospholane-1-sulfide (4b) in the mixture in a ratio of 3:2: Calculated for C16H25PS: C, 68.53%; H, 8.99%; found: C, 68.4%; H, 8.0%; 1H NMR (400.13 MHz, CDCl3) δ 0.91 (t, 3J = 6.8 Hz, 6H, C(6')H), 1.25–1.43 (m, 16H, C(2')H, C(3')H

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• mid to late 1970s. I was fortunate to do undergraduate research with Professor Hans J. Reich, investigating the mechanism of the singlet oxygen reaction with alkenes and studying the oxidation of selenide/sulfide mixtures using ozone and singlet oxygen [1]. In my senior year, I took three graduate

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• for the key intramolecular acyl transfer reaction to form the cyclononene motif. After sodium periodate oxidation of sulfide 56 to the corresponding sulfoxide, addition of lithium diisopropylamide initiated the intramolecular acyl transfer and led to formation of cyclononene 57 in quantitative yield