Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• disulfides, sulfides or even thiols [167]. However, their use in organophotocatalysis is scarce. In substoichiometric quantities, they are efficient H atom shuttles and play a primordial role in hydrogen transfer mechanisms. For this reason, one of their major applications is the HAT to the cocatalyst

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• ]. This reaction broadened the portfolio of CF2PO(OEt)2-containing molecules leading to the corresponding compounds in good to excellent yields (Scheme 9). Note that the versatility of this methodology was further proved through its application to disulfides [52] with moderate to good yields. Poisson and

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• Figure S2 in Supporting Information File 1). Cs2CO3-mediated C(Het)–S bond formations of a heteroazole such as imidazo[1,2-a]pyridine, oxadiazole, and benzimidazole with diaryl disulfides without a transition metal catalyst have previously been developed [18][19]. The key step in these reactions is

Insertion of [1.1.1]propellane into aromatic disulfides

• Robin M. Bär,
• Gregor Heinrich,
• Martin Nieger,
• Olaf Fuhr and
• Stefan Bräse

Beilstein J. Org. Chem. 2019, 15, 1172–1180, doi:10.3762/bjoc.15.114

• , 76344 Eggenstein-Leopoldshafen, Germany 10.3762/bjoc.15.114 Abstract Herein we present the synthesis of symmetrically and unsymmetrically substituted 1,3-bissulfanylbicyclo[1.1.1]pentanes from disulfides and [1.1.1]propellane. Bicyclo[1.1.1]pentanes (BCPs) recently gained interest as rigid linkers and

• , but has never been thoroughly investigated. In this study, we show that an UV initiated radical reaction can be used to synthesize symmetrically and unsymmetrically substituted BCP sulfides by reaction of [1.1.1]propellane (1) with disulfides. Depending on the ratio of 1 to the disulfide, only the BCP

• in most cases. Single crystal X-ray diffraction analysis confirms the rod-like structure of the [2]staffanes that is often required in material applications. Keywords: bicyclo[1.1.1]pentane; bioisosteres; disulfides; linkers; [1.1.1]propellane; Introduction Rigid structures are emerging in both

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• with the one obtained for the ortho-methyl product 1e. Compound 1o indicates some level of tolerance towards functional groups that can be used à posteriori to modify the product. Diaryl disulfides 26 were isolated in yields ranging from 2 to 36%, depending on the thiophenol. Attempts at S

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• reversibility and thermodynamic control in mechanochemical covalent synthesis, towards base-catalyzed metathesis of aromatic disulfides as a model reaction [87]. The outcome of solution-phase chemistry and mechanochemical synthesis were well distinguished and they have described the phenomenon based on

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

• thiols (Scheme 1) [17][18][19][20][21], other methodologies employing different sulfur sources such as disulfides or silylsulfides have been described, which most of them involves metals, e.g., indium [22], copper [23], mercury [24], or organocatalysts [25]. β-Ketosulfides, in addition, play an important

Metal-free C–H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

• Yan Xiao,
• Bing Jing,
• Xiaoxia Liu,
• Hongyu Xue and
• Yajun Liu

Beilstein J. Org. Chem. 2019, 15, 279–284, doi:10.3762/bjoc.15.24

• with DMSO and give an active intermediate, which can further convert benzothiazole to 2-mercaptobenzothiazole. Indeed, several articles have reported that thiols can be oxidized by DMSO to the corresponding disulfides [38][39]. Based on the above results and related references, a plausible reaction

• pathway is proposed (Scheme 3). Initially, 1,3-propanedithiol is possibly oxidized to disulfides 4 and 5 by DMSO. We failed to isolate and determinate these two sulfides, possibly because they are very active in the following coupling reactions. Both disulfides coupled with 1a to give the same C–S

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

• disulfides in the presence of catalytic amounts of [Ir(dF(CF3)ppy)2(dtbpy)]PF6 and (NH4)2S2O8 under blue light irradiation to yield arylthiols. The reaction proceeds at room temperature and avoids the use of prefunctionalized arenes. Experimental evidence suggests a radical–radical cross coupling mechanism

• , electron poor arenes are required. In this article, we report the development of a mild and efficient oxidative photocatalytic method of thiolation of electron-rich di- and trimethoxybenzene arenes with aryl disulfides and (NH4)2S2O8 as terminal oxidant (Scheme 2). Results and Discussion 1,2,4

• cleavage has been reported for alkyl and aryl disulfides in an oxidative [44][45][46] and triplet sensitized mechanism [47]. It is also well known in literature that aromatic disulfides are cleaved homolytically under UV irradiation yielding the corresponding radicals [48]. A recent study from Nicewicz

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

• structural characteristic of peptides is the disulfide bridge formed by cysteines. This functional group is much more prevalent in peptide medicinal chemistry. Noël et al. have published a protocol for the aerobic oxidation of thiols to disulfides, using Eosin Y photocatalysis and TMEDA (Scheme 3) [43]. The

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

• makes them highly susceptible to nucleophilic attack and makes them versatile starting materials for the synthesis of various derivatives [16][17][18]. A number of protocols have been reported to effect their selective ring opening using thiols or disulfides as nucleophiles to obtain β-hydroxy sulfides

• biocatalysis for the asymmetric synthesis of β-hydroxy sulfides still remains unexplored. 3.1.2 Disulfides as nucleophiles. Whilst thiols are excellent nucleophiles and can open epoxides under a variety of conditions as detailed above, they can be awfully odoriferous and unpleasant to work with [58]. As an

• alternative, Soleiman-Beigi et al. reported an epoxide opening using disulfides in the presence of sodium metal in THF at room temperature (Scheme 23) [59]. The reaction is compatible with different kinds of epoxides possessing substituents such as alkyl, aryloxy and phenylepoxy, and the nature of the

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

• respective diaryliodonium salts 1. An atom efficient S-arylation of tetraalkylthiuram disulfides 6 was developed by Dong and co-workers under Cu(I)-catalysis (Scheme 5) [28]. This reaction yields two equivalents of S-aryl dithiocarbamates 7 and 7’ in typically high yields applying only one equivalent of a

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

• . General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways. Keywords: disulfides; photocatalysis; sulfones; sulfoxides; thiols; visible light

• 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

• gave better yields than their bromo or chloroanalogues, because of their higher fragmentation stability after single-electron reduction. Disulfides Formation of sulfides Jacobi von Wangelin and co-workers published a photocatalyzed protocol for the formation of aryl sulfides from the respective aryl

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• as source of SCF3 for direct trifluoromethylsulfenylation. 1 Trifluoromethylation Csp3–CF3 bond-forming reactions Synthesis of α-trifluoromethyl ketones from alkenes: After their original reports on the trifluoromethylation of aromatics (see later in the text, Scheme 34) [16] and disulfides (Scheme

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

• six-membered heterocycles are discussed. Applications of dialkyl dicyanofumarates as oxidizing agents in the syntheses of disulfides and diselenides are described. The reactions with metallocenes leading to charge-transfer complexes with magnetic properties are also presented. Keywords: cycloaddition

• 97 were subjected to reactions with E-1a under the same reaction conditions, cyclic disulfides 98 were obtained as products of a redox reaction [72]. The analogous reaction course was observed with selenols, which were converted into the corresponding diselenides in good yields. The formation of

• disulfides and diselenides is explained as a redox process through a single-electron transfer (SET) mechanism with E-1a as the oxidizing reagent, which converted into a mixture of diastereoisomeric diethyl dicyanosuccinates 96 [72]. Very likely, an analogous SET mechanism governs also the reaction of E-1

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• products to form disulfides. However, it was found that treatment of the crude reaction mixture with PBu3 reduced the disulfides allowing for smoother isolation. Importantly, in a second step the unprotected thiol was able to ligate a selenylsulfide-activated single-cysteine mutant protein (subtilisin

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• and as effective tool in the immunological field). Review Synthesis of glyco-gold nanoparticles Despite the great inertness of this noble metal, Au can form stable bonds with sulfur-containing compounds (i.e., thiols or disulfides) [9][10] and it is possible to easily and robustly functionalize AuNPs

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

• Jing Leng Shi-Meng Wang Hua-Li Qin School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 205 Luoshi Road, Wuhan 430070, PR China 10.3762/bjoc.13.91 Abstract A highly efficient and chemoselective method for the synthesis of diaryl disulfides is developed via a

• visible light-promoted coupling of readily accessible arenediazonium tetrafluoroborates and CS2. This practical and convenient protocol provides a direct pathway for the assembly of a series of disulfides in an environmentally friendly manner with good to excellent yields. Keywords: arenediazonium

• tetrafluoroborates; carbon disulfide; chemoselectivity; diaryl disulfides; photocatalyst; Findings The development of methods for the functionalization of peptides and proteins under mild conditions is a current frontier in the fields of chemistry, biology and drug discovery [1][2][3][4]. Most of the

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

• Loïc Pantaine,
• Vincent Humblot,
• Vincent Coeffard and
• Anne Vallée

Beilstein J. Org. Chem. 2017, 13, 648–658, doi:10.3762/bjoc.13.64

• interest in the past decades because of their potential applications in various areas such as biomaterials, tissue engineering, biosensors and electronics [1][2][3]. The seminal work of Nuzzo and Allara on the adsorption of disulfides on gold surface has triggered numerous research activities in the

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

• with aryl iodides at 90 °C in the presence of CuI as catalyst to afford biaryl disulfides and polysulfides, which could be further converted to aryl thiols through a followed reduction using NaBH4 or PPh3 (Scheme 59) [103]. A wide range of functional groups including methoxy, hydroxy, acyl, carboxy

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• reported a metal-free photocatalytic aerobic oxidation of thiols to disulfides under continuous-flow conditions [64]. Disulfides are useful molecules employed as drugs, anti-oxidants or pesticides as well as rubber vulcanizating agents [65]. Symmetric disulfides are generally obtained by oxidative coupling

• dilution with pure EtOH was needed at the output to avoid clogging (Scheme 12). The residence time of 20 min guaranteed a limited irradiation time and high purity of the products. The disulfides were obtained with excellent yields, and the process was executed on challenging thiols as in the case of

• . (Adapted with permission from [53], copyright 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim). Continuous flow process setup for the preparation of 11 (Reproduced with permission from [54], copyright 2015 American Chemical Society). Continuous-flow photocatalytic oxidation of thiols to disulfides

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

• 1,1'-disulfides in nearly quantitative yields. The complexes LMo(CO)5 (L = 3-hexyl-1-phenylphospholane, 3-benzyl-1-methylphospholane, 1,2-bis(1-phenylphospholan-3-yl)ethane, and 1,6-bis(1-phenylphospholan-3-yl)hexane were prepared by the reaction of 3-substituted phospholanes and α,ω-bisphospholanes

• '-dioxides 11a–c and bisphospholane 1,1'-disulfides 12a–c (Scheme 6). Diastereomeric cleavage of signals in the 13С NMR spectra of bisphospholanes observed only for compounds 10а, 10d, 11а, 12а in which the phospholane moieties are linked by two methylene groups, obviously as a result of mutual influence of

Optimized methods for preparation of 6^I-(ω-sulfanyl-alkylene-sulfanyl)-β-cyclodextrin derivatives

• Eva Bednářová,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2016, 12, 349–352, doi:10.3762/bjoc.12.38

• and repeating units (ethylene glycol or methylene). The target compounds were characterized by IR, MS and NMR spectra. A simple method for their complete conversion to the corresponding disulfides as well as a method for the reduction of the disulfides back to the thiols is presented. Both, thiols and

• disulfides are derivatives usable for well-defined covalent attachment of cyclodextrin to gold or polydopamine-coated solid surfaces. Keywords: cyclodextrins; disulfides; monosubstituted derivatives; thiols; Introduction Cyclodextrins (CDs) [1], cyclic oligomers of α-D-glucopyranose, are used for their

• preparation of this type of sulfanyl derivatives – formation of disulfide byproducts – was not addressed in the literature at all. Therefore, we decided to develop more general procedures for the preparation of such CD derivatives and also a method for controlled preparation of corresponding disulfides, which