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

• Penadès and co-workers [15] is a modified Brust–Shiffrin method [17], based on the in situ Au3+ reduction by means of NaBH4 in the presence of thiol-ending neoglycoconjugates. Following this approach, a rapid synthesis of AuNPs characterized by elevated glycan density on the NP surface and a 1–10 nm

• the “thiol for thiol” ligand exchange method, which allows the superficial diversification by introducing small amounts of different ligands after the AuNP synthesis [11][12][18]. Recently, the Seeberger group reported a straightforward one-pot method to prepare glucose-stabilized ultrasmall AuNPs, by

• procedure for the immobilization of carbohydrates on the nanoparticles surface [27]. The AuNPs were firstly coated with a PFPA-thiol monolayer via a ligand-exchange reaction, then carbohydrates were immobilized by means of a photocoupling reaction. Glyco-gold nanoparticles: design and structural properties

Conformational study of L-methionine and L-cysteine derivatives through quantum chemical calculations and ³J_HH coupling constant analyses

• Weslley G. D. P. Silva,
• Carolyne B. Braga and
• Roberto Rittner

Beilstein J. Org. Chem. 2017, 13, 925–937, doi:10.3762/bjoc.13.94

• disulfide bonds formed by the oxidized thiol groups of cysteine confer exceptional stability for the peptides and proteins where they are present [10]. Thus, a systematic study on the conformational behavior of L-Met and L-Cys can reveal unique properties about the formation of proteins and peptides that

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

• have been investigated for the immobilization of a target molecule through a reaction with the terminal groups of the SAMs. The most common methods to covalently functionalize these materials involve the Huisgen cycloaddition between an azide and an alkyne [8][9], Thiol-Michael addition [10][11], amide

• previously observed by PM-IRRAS and contact angle measurements. In this work the S2p signal is particularly important because it allows the characterization of the SAM formation via thiol moieties and especially evaluating the conversion rate of the reaction since the XPS signature of the sulfamide moiety

• must be very different from the one of thiol moiety. The all four samples highlight a strong S2p3/2,1/2 doublet at 162.0 ± 0.1 eV (S2p3/2) (blue) characteristic of the thiolate-gold bond [50] with an additional XPS peaks doublet at lower binding energy of 161.1 ± 0.1 eV (green) attributed to

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

• has not been reported. In this review, a brief overview is given of the recent advances in synthetic strategies for both phenols and aryl thiols. Keywords: aryl thiol; C–O bond; C–S bond; phenol; transition metal; Introduction Phenols and aryl thiols serve as both important intermediates in organic

• before the formation of copper complex. In 2016, the Wang and Shi group reported a CuI-catalyzed C–H hydroxylation of thiophenols, in which disulfide directed the hydroxylation [58]. Using aryl thiol and arylboronic acid as starting materials, C–H hydroxylation and C–S coupling sequentially occurred in

• methods for aryl thiol preparation was not observed. There may be two reasons which block the development of synthetic methods for aryl thiols: (1) Traditionally, sulfur was considered poisonous to transition metal catalysts [93][94]; (2) aryl thiols are very reactive forming intermolecular or

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

• induced thiol–yne click reaction. Using this reaction, we could greatly enhance the CMP nanomembrane synthesis and further broaden the variability of the LbL approach. Keywords: click chemistry; conjugated microporous polymers (CMPs); microporous materials; nanomembranes; thin films; thiol–yne coupling

• catalyst-free thiol–yne coupling (TYC) reaction. TYC has gained large attention as a representative of the click chemistry concept [17]. In the TYC reaction, usually a photoinitiator creates thiyl radicals [18][19][20], which react with nearby alkyne moieties to form covalent sulfur–carbon bonds and vinyl

• 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

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

• of thiols [66]. Noël and co-workers set up a microflow system equipped with a mass flow controller (MFC) able to introduce pure oxygen as the oxidant to oxidize a solution of thiol containing 1% of Eosin Y. The flow stream was exposed to white LED light in order to activate the reaction, and a

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• nucleophilic attack by the terminal phosphopantetheine thiol of the ACP domain. Recent steady-state kinetic analysis of an AT domain sourced from DEBS module 3 (Figure 3) has provided evidence that the specificity for (2S)-methylmalonyl-CoA is expressed during the first half reaction of the ping-pong mechanism

Posttranslational isoprenylation of tryptophan in bacteria

• Masahiro Okada,
• Tomotoshi Sugita and
• Ikuro Abe

Beilstein J. Org. Chem. 2017, 13, 338–346, doi:10.3762/bjoc.13.37

• the thiol groups of proteins in eukaryotes. In contrast, the Bacillus quorum sensing peptide pheromone, the ComX pheromone, possesses a posttranslationally modified tryptophan residue, and the tryptophan residue is isoprenylated with either a geranyl or farnesyl group at the gamma position to form a

• referred to as the farnesylation or geranylgeranylation of the thiol group of the C-terminal cysteine residue in peptides and proteins [4][5][6][7]. The isoprenylation of cysteine was first found in the peptide pheromones of basidiomycetous yeast [8][9][10]. Two peptide pheromones, tremerogen A-10 and

A novel method for heterocyclic amide–thioamide transformations

• Walid Fathalla,
• Ibrahim A. I. Ali and
• Pavel Pazdera

Beilstein J. Org. Chem. 2017, 13, 174–181, doi:10.3762/bjoc.13.20

• from I followed by electron delocalization and the overall formation of cyclohexyl isothiocyanate (4) via C–S bond cleavage and the formation of quinazoline thiol anion II having a negative charge concerted on the nitrogen atom. The protonated cyclohexylamine in the previous step will transfer this

Nucleophilic displacement reactions of 5′-derivatised nucleosides in a vibration ball mill

• Olga Eguaogie,
• Patrick F. Conlon,
• Francesco Ravalico,
• Jamie S. T. Sweet,
• Thomas B. Elder,
• Louis P. Conway,
• Marc E. Lennon,
• David R. W. Hodgson and
• Joseph S. Vyle

Beilstein J. Org. Chem. 2017, 13, 87–92, doi:10.3762/bjoc.13.11

• stoichiometry to the ball mill reaction gave complete and clean conversion of CldA (1a) into MobSdA (2a) monitored by TLC within 1 h in a previously unused steel vessel (Table 1, entry 1). The efficiency of chloride displacement from CldA (1a) was compromised in the presence of fewer equivalents of thiol (Table

Synthesis and evaluation of anti-oxidant and cytotoxic activities of novel 10-undecenoic acid methyl ester based lipoconjugates of phenolic acids

• Naganna Narra,
• Shiva Shanker Kaki,
• Rachapudi Badari Narayana Prasad,
• Sunil Misra,
• Koude Dhevendar,
• Venkateshwarlu Kontham and
• Padmaja V. Korlipara

Beilstein J. Org. Chem. 2017, 13, 26–32, doi:10.3762/bjoc.13.4

• methyl 10-undecenoate which was subjected to a thiol–ene reaction with cysteamine hydrochloride. Further amidation of the amine was carried out with different phenolic acids such as caffeic, ferulic, sinapic, coumaric and cinnamic acid. All synthesized compounds were fully characterized and their

• lipoconjugates of phenolic acids is reported. The synthetic route was simple with product yields in the range of 84–86% over three steps. The lipid part, methyl 10-undecenoate was subjected to a thiol–ene reaction with cysteamine hydrochloride and the resulting intermediate was conjugated with the phenolic acid

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• nm, respectively, as well as a broad minor peak at λ = 548 nm (Figure 2a). The peaks at λ = 420 and 450 nm are caused by different protonation states of the thiol side chain of the proximal heme ligand cysteine: P450 enzymes displaying a protonated thiol ligand (as indicated by a peak at λ = 420 nm

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• derived from monosaccharides by reduction of the carbonyl group, by oxidation of at least one functional group at the end of the chain in carboxylic acid, by replacement of one or more hydroxy groups by a hydrogen atom, an amine, a thiol or any similar group are also called carbohydrates. Carbohydrates

Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

• Federica Santoro,
• Matteo Mariani,
• Federica Zaccheria,
• Rinaldo Psaro and
• Nicoletta Ravasio

Beilstein J. Org. Chem. 2016, 12, 2627–2635, doi:10.3762/bjoc.12.259

• antioxidants in polymers [6]. They are typically synthesized through the condensation of a thiol with organic halides under strong basic conditions [7][8][9], but due to the high toxicity of alkyl halides the introduction of new methods of access to this kind of materials is desirable. The ideal reaction from

• totally unreactive. As far as the thiol is concerned both aromatic and cyclic thiols gave excellent results. The attempt to carry out the reaction in a solvent-free mode gave surprising results. The reaction was slower but selectivity was still very high. Results are reported in Table 2. Aromatic and

• nucleophilic substitution mechanism: the higher the electronic density on the carbinol C atom, the higher the reaction rate. When the electronic density is somewhat lower, competitive formation of the ether occurs but subsequent nucleophilic addition of the thiol to the ether restores a very high selectivity

Synthesis of three-dimensional porous hyper-crosslinked polymers via thiol–yne reaction

• Mathias Lang,
• Alexandra Schade and
• Stefan Bräse

Beilstein J. Org. Chem. 2016, 12, 2570–2576, doi:10.3762/bjoc.12.252

• Eggenstein-Leopoldshafen, Germany 10.3762/bjoc.12.252 Abstract Herein we report the syntheses of two porous hyper-crosslinked polymers (HCPs) via thiol–yne reaction with rigid tetrahedral and pseudo-octahedral core structures. Sorption measurements with nitrogen gas at 77 K revealed BET-surface areas up to

• 650 m²/g. Those networks also showed a high thermal stability as well as insolubility in common organic solvents. Keywords: three-dimensional; porous hyper-crosslinked polymers; thiol–yne; Introduction The synthesis of different organic networks has been previously reported. Among them, especially

• tetraphenylmethane-based networks by another click reaction, the thiol–yne reaction [14][15][16][17][18][19]. This reaction type has been known for several decades and relived a renaissance in the past decade, especially in material sciences [20][21][22][23][24][25][26][27][28][29][30][31][32], due to its mild, and

Methylenelactide: vinyl polymerization and spatial reactivity effects

• Judita Britner and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232

• recently investigated [8]. Up to now, it was not possible to polymerize MLA via ring opening [9]. Only indirectly, unsaturated polylactide carrying vinyl side groups can be obtained through a copolymerization of chlorolactide with L-lactide followed by subsequent dehydrochlorination [10]. Recently, thiol

• attack of the thiol takes place. This can be clearly seen in the 1H NMR spectra (Figures S18 and S19, Supporting Information File 1). Thioacetic acid was used as a potential chain-transfer agent due to its lower nucleophilicity. However, a complete thiol-Michael addition can be seen in Figure 8 (not full

• conversion of MLA due to the impurities of thioacetic acid like disulfide and acetic acid). In this context, the iodine catalyzed thiol-Michael addition was investigated [11]. Controlled radical polymerization of MLA via RAFT Since MLA acts as a vinyl monomer, it was also interesting to evaluate the

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• as sodium hydride, to activate the thiol group of 3-mercaptopropionic acid (MPA) and N,N-dimethylformamide (DMF) [16]. In the reaction solution and particularly on larger scales (from 10 g to kilo lab scale), impurities that arise from incomplete conversions, product and byproduct decomposition as

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

• libraries of reversibly interconverting building blocks. The syntheses of phosphoramidite building blocks derived from D-threoninol are presented in two variants with protected amino or thiol groups. The threoninol building blocks were successfully incorporated via automated solid-phase synthesis into 13mer

• ][26][27][28]. Similarly, a thiol functionality can be introduced by substitution of the amine group of threoninol and incorporated into the oligonucleotide backbone. The amine and thiol groups can be used for further oligonucleotide functionalization reacting these sites with functional molecules like

• template-directed selection of one nucleobase from the reaction mixture with the amine or thiol functional group was investigated [44][45][46][47]. In our studies, dynamic chemistry is applied for post-synthetic functionalization of the threoninol based modified oligonucleotides in a reversible manner

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

• , entries 2–6). For per-O-benzylated glucal (3) and per-O-acetylated rhamnal (5), the corresponding thiol-2-deoxyglycosides 7 (61%, α:β = 2:1) and 10 (76%, α:β = 2:1) were produced in good yields with moderate stereoselectivity (Table 1, entry 2 and 5). Interestingly, as shown in Table 1, entries 1 and 2

• sequential steps (Scheme 1). Monosaccharide acceptor 64 underwent the TMSBr-mediated nucleophilic addition to glucal 1 to produce exclusively disaccharide 65 (97%, α:β = 7:1) in an excellent yield with high α-selectivity. Remarkably, the 1-thiol group remained intact after the formation of disaccharide 65

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• paraffin-like oligomeric chains bearing polymerizable vinyl moieties. These oligomers were radically crosslinked in bulk with N-VP as co-monomer yielding swellable polymer disks. The vinylic side groups of the N-VP oligomers allow thiol–ene click reactions with 2-aminoethanethiol hydrochloride to obtain

• poly(ethylene glycol) side chains. Keywords: double alkylation; modified N-vinylpyrrolidone; oligomeric anthraquinone dye; paraffin-like oligomer; radical thiol-ene click reaction; Introduction Poly(N-vinylpyrrolidone) (PVP) is established in daily life due to its high water solubility and

• present the synthesis of paraffin-like oligomers via double alkylation of N-VP with 1,8-dibromooctane. Additionally, this work focuses on the use of the free double bonds for radical crosslinking as well as thiol-ene modification for subsequent dye attachment. Results and Discussion N-Vinylpyrrolidone (1

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• oxidise the cysteine. A mechanistic proposal based on structural data involves the oxidation of the thiol to a thioaldehyde, which then functions as an electron sink to facilitate decarboxylation to generate the double bond between Cα and Cβ [66] (Figure 5A). The functional characterisation of EpiD led to

• generate a 5’-deoxyadenosyl radical (5’-dA•). The formation of 5’-dA• is common to all radical SAM proteins. The second [4Fe-4S] cluster coordinates the peptide substrate via a deprotonated thiol group of a cysteine. The 5’-dA• abstracts a hydrogen from a specific α-carbon, which then attacks the thiol

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• to the enantioselective addition of aromatic thiols to 2-phthalimidoacrylates 29 in high yield and good enantioselectivity (Scheme 7) [24]. A variety of electron rich, neutral, and poor thiols coupled efficiently. Impressively, the aromatic thiol 28 could be substituted with hydroxy and amino groups

• (Scheme 23c). Following Tan’s work on the conjugate addition–enantioselective protonation of cyclic itaconimide 95, both the Singh and Chen groups investigated the addition of thiol nucleophiles to acyclic imides. Utilizing thiourea catalyst 102a, Singh and co-workers reported the catalytic

• in high yield and enantioselectivity. Only when R1 was phenyl did the enantioselectivity of the thiol addition drop below 91.5:8.5 er to 85:15 er. The addition of a variety of α-substituted malononitriles 126e also proceeded in high yield and enantioselectivity. During the exploration of different

A cross-metathesis approach to novel pantothenamide derivatives

• Jinming Guan,
• Matthew Hachey,
• Lekha Puri,
• Vanessa Howieson,
• Kevin J. Saliba and
• Karine Auclair

Beilstein J. Org. Chem. 2016, 12, 963–968, doi:10.3762/bjoc.12.95

• pantothenamides may mimic pantetheine and are extended into a thiol-lacking coenzyme A (CoA) derivative by some of the natural CoA biosynthetic enzymes (pantothenate kinase or PanK, phosphopantetheine adenylyltransferase and dephosphocoenzyme A kinase). The resulting inactive CoA analog affects downstream

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• for the preparation of organosulfur compounds render thioether derivatives [96][97], this approach provides products with a free thiol group such as the α-mercaptocarboxylic acid derivative 67 (Scheme 11). Additionally, these mercapto derivatives can also be S-alkylated by treatment with the

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• -mediated hydrogen bonds, involving the thiol moiety [61]. In other words when DIMEB CD was used, the presence of both CH3 and OH moieties induced a tight host–guest interaction in which the C=S group is coordinated outside the cavity through hydroxy groups via H bonds. Conclusions With the prospect to