Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• -Methylbenzyl isothiocyanate (2): To a solution of (R)-1-phenylethylamine (3.000 g, 3.151 mL, 24.76 mmol, 1.0 equiv) in anhydrous diethyl ether (20 mL), cooled to 0 °C and under a nitrogen atmosphere, carbon disulfide (12.065 g, 158.46 mmol, 9.6 mL, 6.4 equiv) and N,N′-dicyclohexylcarbodiimide (5.109 g, 24.76

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

• Marcus Frings,
• Isabelle Thomé and
• Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

• hydrochloric acid or calcium chloride in aqueous ethanol allowed the isolation of α-aminosulfoximine (R)-8. In all cases the starting material was fully consumed and degraded. As decomposition products N-methylbenzenesulfinamide and diphenyl disulfide were identified and isolated. Hence, α-aminosulfoximine (R

Algicidal lactones from the marine Roseobacter clade bacterium Ruegeria pomeroyi

• Ramona Riclea,
• Julia Gleitzmann,
• Hilke Bruns,
• Corina Junker,
• Barbara Schulz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2012, 8, 941–950, doi:10.3762/bjoc.8.106

• analytically pure dichloromethane, and the obtained extracts were analysed by GC–MS. A representative chromatogram of a headspace extract of R. pomeroyi is shown in Figure 2A. The sulfur volatiles dimethyl disulfide, dimethyl trisulfide, and S-methyl methanethiosulfonate, previously reported from several other

Multistep organic synthesis of modular photosystems

• Naomi Sakai and
• Stefan Matile

Beilstein J. Org. Chem. 2012, 8, 897–904, doi:10.3762/bjoc.8.102

• new method introduced to secure facile access to complex architectures. Chemoorthogonal to the ring-opening disulfide exchange used for SOSIP, hydrazone exchange is then introduced to achieve stack exchange, which is a “switching” technology invented to drill giant holes into SOSIP architectures and

• fill them with functional π-stacks of free choice. Keywords: asparagusic acid; charge-transfer cascades; chromophores; disulfide exchange; hydrazone exchange; molecular switches; naphthalenediimides; π-stacks; surface-initiated polymerization; Introduction The architecture of photosystem 1 is rather

• 21. After chemoselective, acid-catalyzed deprotection, the liberated amines were coupled with the Boc-protected cysteine tert-butyl disulfide 22. The obtained amide 23 was treated with TFA for Boc removal and coupled with the geminal diphosphonate foot 7. Deprotection of both hydrazides and

Building photoswitchable 3,4'-AMPB peptides: Probing chemical ligation methods with reducible azobenzene thioesters

• Gehad Zeyat and
• Karola Rück-Braun

Beilstein J. Org. Chem. 2012, 8, 890–896, doi:10.3762/bjoc.8.101

• thiol molecule at the N-sulfenohydrazodiarene B, yielding the symmetric disulfide and the respective hydrazine thioester or hydrazine peptide (Scheme 3, reaction 2). The reduction of diazene units by thiols has been intensively studied in the past for electron-poor azobenzenes or azodicarboxylates, en

Intramolecular bridges formed by photoswitchable click amino acids

• Christian Hoppmann,
• Ronald Kühne and
• Michael Beyermann

Beilstein J. Org. Chem. 2012, 8, 884–889, doi:10.3762/bjoc.8.100

• spacing, whereas for peptide 2 with i,i+7 spacing only traces of the intramolecular click product were observed. Most notably, for peptide 2 (i,i+7) the predominate formation of the disulfide 4 was detected, indicating that the intramolecular thiol–ene click reaction within i,i+7 helical spacing is

Synthetic glycopeptides and glycoproteins with applications in biological research

• Ulrika Westerlind

Beilstein J. Org. Chem. 2012, 8, 804–818, doi:10.3762/bjoc.8.90

• between a N-glycopeptide and other peptide/protein fragments [51][52][53]. The glycoprotein contains eight cysteines locked up as disulfide bridges, which need to be correctly folded to obtain an active enzyme [54][55][56]. In one study, a complex type N-glycopeptide (fragment 17) was prepared by standard

• RNase fragment 26–124 (20) to the thioester peptide fragment RNase 1-25 (21) was followed to give RNase fragment 1–124 (22). The formed RNase C protein was then folded by treatment with glutathione disulfide (GSSG) resulting in an active RNase C enzyme (23) (Scheme 3). Recently, the 111-amino-acid long

Formation of carbohydrate-functionalised polystyrene and glass slides and their analysis by MALDI-TOF MS

• Martin J. Weissenborn,
• Johannes W. Wehner,
• Christopher J. Gray,
• Robert Šardzík,
• Claire E. Eyers,
• Thisbe K. Lindhorst and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2012, 8, 753–762, doi:10.3762/bjoc.8.86

• very convenient, yielding more robust and reproducible analyses, and negating the need to search for “sweet spots”, as no crystal formation is required, in contrast to conventional MALDI-TOF MS analysis. Interestingly, both Na and K cation adducts of Man–Trt 5 and its disulfide 8 were observed (Scheme

•  2). The relative ratios of the monomer 5 and the disulfide 8 were found to be concentration-dependent in the analysis on stainless steel (Supporting Information File 1). It was observed that at 15 nmol, almost exclusively the disulfide 8 was detected. Conversely at 50 pmol only K+ and Na+ adducts of

• /DIPEA, dry DMF, overnight, rt, 74%, (c) HATU/DIPEA, dry DMF, 3 h, rt, 71%. The Man–Trt compound 5 forms the disulfide 8 during UV ionisation in MALDI-TOF MS analysis. Supporting Information Supporting Information File 80: Enzyme expression and MALDI MS spectra. Acknowledgements We thank Dr Stephan

Synthesis and antiviral activities of spacer-linked 1-thioglucuronide analogues of glycyrrhizin

• Christian Stanetty,
• Andrea Wolkerstorfer,
• Hassan Amer,
• Andreas Hofinger,
• Ulrich Jordis,
• Dirk Claßen-Houben and
• Paul Kosma

Beilstein J. Org. Chem. 2012, 8, 705–711, doi:10.3762/bjoc.8.79

• -substitution product 5 (3%) and the disulfide oxidation product of 1-thiol 3 was observed in only very minor quanities. The corresponding 2-iodoethyl derivative 6 was prepared by a Finkelstein reaction from the bromoethyl 1-thioglycoside 4 in 95% yield (Scheme 1). The previously reported 3β-amino derivative of

Volatile organic compounds produced by the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria 85-10

• Teresa Weise,
• Marco Kai,
• Anja Gummesson,
• Armin Troeger,
• Stephan von Reuß,
• Silvia Piepenborn,
• Francine Kosterka,
• Martin Sklorz,
• Ralf Zimmermann,
• Wittko Francke and
• Birgit Piechulla

Beilstein J. Org. Chem. 2012, 8, 579–596, doi:10.3762/bjoc.8.65

• setup, either promotion or inhibition of plant growth was observed [25][27][31][32][33][34][35]. Individual compounds such as acetoin and 2,3-butanediol acted as plant-growth-promoting agents [31], while dimethyl disulfide and 2-phenylethanol inhibited plant growth [34][36]. The inhibitory potential of

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• the production of various arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides), from the corresponding diaryl disulfides or aryl thiols. The method consists of two steps: (Step 1) treatment of a diaryl disulfide or an aryl thiol with chlorine in the presence of

• stepwise fluorination of diphenyl disulfide with expensive silver difluorides (AgF2) in a fluorocarbon solvent [3]. However, the yield was only 9%. Since then, many substituted phenylsulfur pentafluorides have been prepared by this method, but still with very low yields [3][20][31][32]. In 2000, a new

• method using molecular fluorine (F2) was reported [33]. Thus, bis(p- or m-nitrophenyl) disulfide was treated with F2 diluted with nitrogen (F2:N2 = 1:9 v/v) at low temperature in acetonitrile to give the nitrophenylsulfur pentafluoride in ca. 40% yield. However, in addition to the low yields, this method

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• of liquid-crystalline and non-liquid-crystalline dendrons were prepared containing thiol or disulfide groups within their structures. Hybrid Au NP materials were prepared with cyanobiphenyl terminated dendron 16 (Figure 19) by using both direct and solvent-mediated ligand exchange methods. The direct

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• all strains were fast-growing [20][21][23][24][25][26][27][28]. Interestingly, some of the bacteria emitted sulfur-containing compounds, such as dimethyl disulfide (11), dimethyl trisulfide (12), and dimethyl tetrasulfide (13), which are known bacterial volatiles [19]; these compounds were not emitted

Synthesis, solid-state fluorescence properties, and computational analysis of novel 2-aminobenzo[4,5]thieno[3,2-d]pyrimidine 5,5-dioxides

• Kenichirou Yokota,
• Masayori Hagimori,
• Naoko Mizuyama,
• Yasuhisa Nishimura,
• Hiroshi Fujito,
• Yasuhiro Shigemitsu and
• Yoshinori Tominaga

Beilstein J. Org. Chem. 2012, 8, 266–274, doi:10.3762/bjoc.8.28

• . Results and Discussion Synthesis Heterocyclic ketene dithioacetals (1a–c) were easily prepared by the condensation of the corresponding heterocyclic active methylene compounds with carbon disulfide in sodium hydroxide solution as a base, followed by methylation with dimethyl sulfate [8][9][10]. The

Derivatives of phenyl tribromomethyl sulfone as novel compounds with potential pesticidal activity

• Krzysztof M. Borys,
• Maciej D. Korzyński and
• Zbigniew Ochal

Beilstein J. Org. Chem. 2012, 8, 259–265, doi:10.3762/bjoc.8.27

• with carbon disulfide (Scheme 8) [17]. Moreover, 11h was subjected to the reaction with aromatic isocyanates to give benzimidazolthiocarbamates 11i and 11j. The synthesized compounds were tested for their fungicidal activity. The evaluation was carried out by determining the percentage inhibition of

Ratiometric fluorescent probe for enantioselective detection of D-cysteine in aqueous solution

• Xiao-bo Zhou,
• Wing-Hong Chan,
• Albert W. M. Lee and
• Chi-Chung Yeung

Beilstein J. Org. Chem. 2011, 7, 1508–1515, doi:10.3762/bjoc.7.176

• ]. The facile cyclization of β- or γ-aminothiols with aldehydes containing fluorescent probes forms the basis for the development of several fluorescent probes [12][13][14][15][16][17]. In addition, cleavage of disulfide-based probes by thiols [18][19][20][21] and other thiol-sensing tactics have been

Advances in synthetic approach to and antifungal activity of triazoles

• Kumari Shalini,
• Nitin Kumar,
• Sushma Drabu and
• Pramod Kumar Sharma

Beilstein J. Org. Chem. 2011, 7, 668–677, doi:10.3762/bjoc.7.79

• , phenoxyacetic acid derivatives and carbon disulfide, respectively. Their antifungal activity was investigated against Aspergillus niger and Fusarium oxysporum. Among the series of synthesized compounds, 7-(3-chlorophenyl)-6,7-dihydro-5H-imidazo[2,1-c][1,2,4]triazole-3-thiol (8, Figure 6) showed the most

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• require very high polymerization temperatures. Star copolymers of polyethylene glycol and polypropylene glycol were crosslinked in inverse miniemulsion via an esterification reaction with a dithiodicarboxylic acid to yield nanogels [124]. The disulfide bonds were subsequently cleaved by reduction to yield

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• not so activating for reaction with CF3SCl. For example, thiophenol [76] forms only phenyltrifluoromethyl disulfide [70]. The presence of a methyl group and halogens requires high temperatures (100–200 °C) and the presence of catalysts (HF or BF3) for reaction and yields of the corresponding

• -nitrochlorobenzene and 2,6-diiodo-4-nitroanisole involve simultaneous reduction and substitution (Scheme 25). Trifluoromethylthiocopper is obtained by reaction of CuBr with AgSCF3 [93][99], the latter is generated from silver fluoride and carbon disulfide [90][100]. To simplify the process, Remy [101][102] suggested

• exception of 4-nitrothiophenol, the reactions are independent of the type of substituents. Unlike many thiophenoxides which bear electron-withdrawing substituents (p-Cl, 2,4-Cl2, o-SO2CHF2 and even p-SO2CF3), sodium 4-nitrothiophenoxide affords 4,4′-dinitrodiphenyl disulfide under these conditions

Bis(oxazolines) based on glycopyranosides – steric, configurational and conformational influences on stereoselectivity

• Tobias Minuth and
• Mike M. K. Boysen

Beilstein J. Org. Chem. 2010, 6, No. 23, doi:10.3762/bjoc.6.23

• phthalimido protected precursor 7 (Scheme 3). Introduction of the 3-xanthogenate with carbon disulfide and methyl iodide yielded 17, which was cleanly deoxygenated in high yield by tributyltin hydride under standard conditions [32][33]. From the resulting compound 18, the ligands 3-deoxy glucoBox 21 with

Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• respectively to the n-hexyl and 6-aminohexyl trisaccharide targets. Unexpectedly, the 6-acetylthiohexyl analogue underwent desulfurization and gave the n-hexyl glycoside product, whereas the 6-benzylthiohexyl analogue gave the desired disulfide trisaccharide dimer. This study constitutes a particularly

• conditions did not lead to the desired corresponding thiol or disulfide product but produced the hexyl glycoside 1. The mechanism proposed to explain this reductive desulfurization is shown in Scheme 4. It involves first a single electron transfer to the thioacetyl group that is followed by the cleavage of

• -benzylthiohexyl glycoside 32 under Birch reduction conditions did not lead to desulfurization and gave the disulfide trisaccharide dimer 3. Under these reductive conditions, and based on the work by Seeberger et al. [52], we did not expect the formation of the disulfide dimer as the major product but rather that

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• developed [122]. A first catalytic enantioselective Friedel–Crafts alkylation with propargyl alcohols as electrophile has been developed by Nishibayashi and co-workers. Chirality was introduced by a thiolate-bridged diruthenium complex which is based on optically active disulfide ligand 120. 2-Alkylfurans

Part 2. Mechanistic aspects of the reduction of S-alkyl- thionocarbonates in the presence of triethylborane and air

• Florent Allais,
• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 46, doi:10.1186/1860-5397-3-46

• possible source of hydrogen atom. This by-product is produced by reaction of ethyl radical, generated from Et3B, with the xanthate function. Deuterated compounds 3–5 were easily prepared from ethanol, carbon disulfide and ethyl bromide (Figure 2). The results reported in Table 2 clearly show that no

The use of chiral lithium amides in the desymmetrisation of N-trialkylsilyl dimethyl sulfoximines

• Matthew J. McGrath and
• Carsten Bolm

Beilstein J. Org. Chem. 2007, 3, No. 33, doi:10.1186/1860-5397-3-33

• , Entry 1), affording 2c in high yield and improved ee (86% yield, 70% ee, Table 2, Entry 2). When N-(diphenylmethylene)-toluenesulfonamide was used as electrophile the sulfoximine adduct 2d was obtained in low yield and ee (Table 2, Entry 3). In contrast, diphenyl disulfide gave sulfide 2e in accepee but