An amine protecting group deprotectable under nearly neutral oxidative conditions

• Shahien Shahsavari,
• Chase McNamara,
• Mark Sylvester,
• Emily Bromley,
• Savannah Joslin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

• conditions is not feasible. In theory, using the one pot approach, once the sulfides in dM-Dmoc were oxidized, β-elimination would follow to give the desired amine products directly. We tested the idea, and as expected, complex mixtures were formed. Reasons for the observation include oxidation of amine

• products by sodium periodate and its reduced products. In addition, we also found that oxidation of sulfides by sodium periodate was significantly slower under basic conditions than under neutral and acidic conditions. To demonstrate the feasibility of selective deprotection of dM-Dmoc protected amines in

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

• , hemithioacetal, various thioesters, thiocarbamate and isothiocyanate. This review article focuses on β-hydroxy sulfides and analogs; their presence in natural products, general protocols for their synthesis, and examples of their application in target oriented synthesis. Keywords: alkene thiofunctionalization

• ; 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

• fascinating biosynthesis of sulfur-containing secondary metabolites can be found in a recent review by Hertweck and co-workers [9]. 2. β-Hydroxy sulfides β-Hydroxy sulfides, often in disguised form, comprise a significant segment of sulfur-containing natural products, with a few examples shown in Figure 2

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• . Review Asymmetric oxidation of sulfides Pribam was the first to use chiral iodine reagents [23]. After a long time without further developments in this direction, Imamoto et al. introduced a new class of chiral hypervalent iodine reagents 1 obtained by the reaction of iodosylbenzene with various

• derivatives of L-tartaric acid anhydrides in 1986. A promising asymmetric induction was achieved for the oxidation of sulfides 23 to sulfoxides 24. This marked the beginning of an era of asymmetric oxidation of sulfides. However, the presence of C2 symmetry in the chiral unit is essential to obtain decent

• enantioselectivity [24]. Later, Kita et al. used chiral tartaric acid derivatives to synthesize chiral I(V) reagents 2 from PhIO2. This represented the first example of the catalytic use of chiral hypervalent reagents in the oxidation of sulfides to sulfoxides with decent enantioselectivities (ees, Scheme 2a). The

Stepwise radical cation Diels–Alder reaction via multiple pathways

• Ryo Shimizu,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 704–708, doi:10.3762/bjoc.14.59

• Diels–Alder reaction have employed styrenes, the scope is not limited to such electron-rich dienophiles. Bauld and Yoon demonstrated that aryl vinyl ethers, enol ether equivalents, and aryl vinyl sulfides are also promising dienophiles for the reactions (Scheme 2) [17][20][21][22][23][24][25]. We have

• development in our laboratory. GC–MS Monitoring of the oxidative SET-triggered reaction of aryl vinyl ether 1c. Radical cation Diels–Alder reaction of trans-anethole [17]. Radical cation Diels–Alder reactions of aryl vinyl ether and sulfides [17][25]. Radical cation Diels–Alder reaction of aryl vinyl ether (1

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

• fluorination of sulfides having various EWGs at their α-position using Et3N·3HF [9][10]. Since then, we have systematically studied the electrochemical fluorination of numerous organic compounds, heterocycles, and macromolecules by using various fluoride salts such as Et3N·nHF (n = 3–5) and Et4NF·nHF (n = 3–5

• ) [11][12][13][14][15][16][17][18][19]. On the other hand, Simonet and co-workers reported the anodic fluorination of alkyl phenyl sulfides having an EWG on the phenyl group in Et3N·3HF/MeCN to provide α-monofluorinated products in moderate yields [20]. We also achieved the anodic fluorination of benzyl

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

• disulfide, thioamide derivatives and sulfides Disulfides and thiosulfates Sulfoxides Sulfinic acids, sulfinate salts and sulfinamides Sulfonyl halides, sulfonyl hydrazines, thionyl chloride and sulfur dioxide C–S bond formations initiated by irradiation with light of wavelengths shorter than 380 nm or by

• radical initiators as well as photocatalytic reactions, where sulfur-containing substrates act as a sacrificial agent are not discussed in this review [23][24][25][26][27][28]. Review Thiols Formation of sulfides and sulfoxides A large number of photocatalytic C–S bond-forming methods report the

• preparation of sulfides. Non-photocatalytic procedures apply the so-called radical thiol–ene or radical thiol–yne reactions for efficient cross-coupling of thiols with olefins [24][29][30]. In 2013, Yoon and co-workers developed a photoredox-catalyzed version of the radical thiol–ene reaction (Scheme 2) [31

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

• iodoarenes and arylthiols bearing different groups like Me, OMe, F, COCH3, NO2 are equally efficient to undergo cross-coupling reactions producing the corresponding unsymmetrical diaryl sulfides 3a–i in 88–93% isolated yields (Table 2, entries 1–9). No significant influence of electron-donating or electron

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

• , glycosyl sulfones are known to be potential glycosyltransferase inhibitors [13]. Glycosyl sulfoxides and sulfones are prepared from the corresponding sulfides using various oxidizing reagents [5][6][7][10]. Although a number of oxidation methods were developed for the oxidation of simple organic sulfides

• , intolerance of other oxidation susceptible functional groups, etc. Thus, developing a mild and efficient method for the controlled oxidation of sulfides to corresponding glycosyl sulfoxides and sulfones, is of great interest. The utility of hydrogen peroxide–solid adducts in organic synthesis is well explored

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• more usual strategy is the so-called “selective poisoning”, i.e., the improvement of the catalyst’s selectivity by the addition of variable, often large, amount of contaminants, either organic ligands (quinolone [65][66], phosphine [67]), carbon monoxide [68], sulfides [69], sulfoxides [70][71] defined

Conjecture and hypothesis: The importance of reality checks

• David Deamer

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

• universal common ancestor (LUCA) may have originated in hydrothermal vents. The iron-sulfur chemistry proposed for hydrothermal vents was tested by Huber and Wächtershäuser [15][16] who simulated vent conditions with boiling mixtures of iron and nickel sulfides to which various reactants were added. They

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

• , amide, bromo and trifluoromethyl were tolerated in this process. They also showed the application of the developed protocol in the synthesis of aryl alkyl sulfides via a “one-pot reaction”. In 2011, the Xu and Feng group applied CuI-nanoparticles to synthesize aryl thiols through a coupling reaction of

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

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• protonation or quaternization of neutral precursors (imidazoles, amines, phosphines, pyridine or sulfides) with Brønsted acids or haloalkanes/dialkylsulfates, respectively. In the next step, a variety of ionic liquids are obtainable by anion exchange, either through direct treatments with Lewis acids or by

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• disulfides and sulfides, which are involved in the synthesis of ligands and pharmaceutical chiral synthetic precursors [1][2] and in (b) the transfer-hydrogenation reaction catalyzed by bifunctional chiral ruthenium complexes, employed in the synthesis of peptide mimics with an interesting

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

• dichlorophosphines (R′PCl2). Hydrogen peroxide oxidation and treatment with S8 of the synthesized phospholanes and α,ω-bisphospholanes afforded the corresponding 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-oxides, 3-alkyl(aryl)-1-alkyl(phenyl)phospholane 1-sulfides, bisphospholane 1,1'-dioxides, and bisphospholane

• affords phospholane 1-sulfides 4а–h also in quantitative yields (Scheme 3). In the 31Р NMR spectra of phospholane oxides 3a–h and phospholane sulfides 4a–h, the phosphorus signal shifts downfield to ca. 57–70 ppm relative to the initial phospholanes, and the heteronuclear constants 1J(31P13C2) and 1J

• the synthesis of five-membered cyclic organophosphorus compounds, we developed a preparative process for the one-pot conversion of aluminacyclopentanes, obtained in situ by catalytic cycloalumination of olefins or diolefins with AlEt3, to phospholanes, phospholane oxides or phospholane sulfides

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• , biologically relevant conditions were selected (rt, t-BuOH/H2O) and CM involving allyl sulfides that contain functional groups commonly found in DNA-intercalators and N-heteroaromatics were investigated. When a quinoline was present on the allylic sulfide, allylic alcohol was found to be the unique suitable

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides

• Svetlana F. Malysheva,
• Alexander V. Artem’ev,
• Nina K. Gusarova,
• Nataliya A. Belogorlova,
• Alexander I. Albanov,
• C. W. Liu and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 1985–1990, doi:10.3762/bjoc.11.214

• Chemistry, National Dong Hwa University, Hualien 97401, Taiwan 10.3762/bjoc.11.214 Abstract Secondary phosphine oxides react with vinyl sulfides (both alkyl- and aryl-substituted sulfides) under aerobic and solvent-free conditions (80 °C, air, 7–30 h) to afford 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl

• )phosphine oxides in 70–93% yields. Keywords: addition; green method; phosphine oxides; regioselectivity; vinyl sulfides; Findings Tertiary phosphines and phosphine chalcogenides are important organophosphorus compounds that are widely used in industry, organic synthesis, polymer science, medicinal and

• ][20] as well as transition metal catalysts [21][22][23]. Also, examples of the microwave-assisted [24][25] and photoinduced [26] addition are described. Recently, on example of secondary phosphines [27] as well as secondary phosphine sulfides [28] and selenides [29], it has been disclosed that the

Lewis acid-promoted hydrofluorination of alkynyl sulfides to generate α-fluorovinyl thioethers

• Davide Bello and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 1902–1909, doi:10.3762/bjoc.11.205

• Davide Bello David O'Hagan University of St Andrews, School of Chemistry, North Haugh, St Andrews, Fife, KY16 9ST, UK 10.3762/bjoc.11.205 Abstract A new method for the preparation of α-fluorovinyl thioethers is reported which involves the hydrofluorination of alkynyl sulfides with 3HF·Et3N, a

• thioester enols and enolates, important intermediates in enzymatic C–C bond forming reactions. The method opens access to appropriate analogues for investigations in this direction. Keywords: alkynyl sulfides; α-fluorovinyl thioethers; hydrofluorination; Lewis acids; organofluorine; Introduction

• , have a spatial and electrostatic profile consistent with the potential to mimic these enzyme intermediates. There is limited literature for preparing such analogues. We have previously described the preparation of α-fluorovinyl thioethers by hydrofluorination of the corresponding alkynyl sulfides using

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• )phthalimide was employed by the Overman group in their synthesis of (−)-aplyviolene [11]. Heterogeneous PRCs form a second class consisting of semiconductor materials. These are generally metal oxides or sulfides in the form of fine particles that consequently have the additional advantage of easily being

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• ]. Having the sulfide 5 in hand, our next task was to prepare sulfone 6. In this regard, Trost and Curran [32] have reported the conversion of sulfides to sulfones in the presence of other common functional groups such as olefins by reacting with the oxidizing agent, potassium hydrogen persulfate (KHSO5

Highly selective palladium–benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

• Antonio Monopoli,
• Pietro Cotugno,
• Carlo G. Zambonin,
• Francesco Ciminale and
• Angelo Nacci

Beilstein J. Org. Chem. 2015, 11, 994–999, doi:10.3762/bjoc.11.111

• , catalyst loading, temperature and solvents (Table 1). With regard to the influence of ligands, the efficiency of benzothiazole–carbene was compared with that of sulfides II and III, both in the presence and in the absence of PPh3, as it is well known that also chelating N-heterocyclic ligands bearing

Highly selective electrochemical fluorination of dithioacetal derivatives bearing electron-withdrawing substituents at the position α to the sulfur atom using poly(HF) salts

• Bin Yin,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2015, 11, 85–91, doi:10.3762/bjoc.11.12

• mind, we studied comparatively the anodic fluorination of dithioacetal derivatives having various electron-withdrawing groups at their α-positions using various poly(HF) salts [28]. Results and Discussion Various α-substituted methyl phenyl sulfides, 1a, 1c, 1e, and 1g, and their α-phenylthio

• exhibited irreversible multiple oxidation peaks and the first oxidation peak potentials are summarized in Table 1. It was expected that the introduction of an additional phenylthio group to the α-position of the sulfides would decrease their oxidation potentials. However, unexpectedly they are higher than

• those of the corresponding sulfides having a single phenylthio group. Although a detailed reason is not clear at present, the additional phenylthio group does not act as an electroauxiliary, but acts as an electron-withdrawing group. As shown in Table 1, the oxidation potentials of sulfide 1g and

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• coupling. In addition to enol ethers 1, vinyl sulfides and ketene acetals have successfully been cyclized according to Scheme 2 [34][35][36]. An interesting modification of this anodic coupling method was achieved by Yoshida, Nokami and co-workers using the “cation pool” concept [37][38][39]. In this

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• oxidant and it has been employed for the selective oxidation of sulfides to the corresponding sulfoxides, for the preparation of α-methylenecyclohexane [16] and glycosyl sulfoxides [17]. Compared to the widely used peroxy acid MCPBA, MMPP has similar chemical properties, but it is a halogen-free reagent

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• losses during purification, the phosphines are sometimes deliberately transformed into the corresponding oxides (or sulfides). However, this requires an additional reduction step afterwards to get the phosphine back [10][11][12][13][14][15]. Therefore phosphines are sometimes protected by generation of

• formed exclusively and isolated as the phosphine sulfides 140 to prevent lower yields by oxidation to the corresponding oxides. The phosphines 141 were obtained by radical reduction of 140 with tris(trimethylsilyl)silane (TTMSS). However, when Kumaraswamy et al. explored the copper-catalyzed