Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• . Unfortunately, the variety of functional groups requires different protection group strategies and, moreover, changes the reactivity of the nucleobase. Since the discovery of the gold standard of fluorescent base analogues, 2-AP, a multitude of adenine FBAs has emerged [22]. Notable recent examples of adenine

Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles

• Vivek Poonthiyil,
• Thisbe K. Lindhorst,
• Vladimir B. Golovko and
• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2

• unravel the causes of, potential new detection methods for, and novel therapeutic strategies against, many disease states. In the last two decades, glyco-gold nanoparticles have emerged as one of several potential new tools for glycoscientists. Glyco-gold nanoparticles consist of the unique structural

• combination of a gold nanoparticle core and an outer-shell comprising multivalent presentation of carbohydrates. The combination of the distinctive physicochemical properties of the gold core and the biological function/activity of the carbohydrates makes glyco-gold nanoparticles a valuable tool in

• glycoscience. In this review we present recent advances made in the use of one type of click chemistry, namely the azide–alkyne Huisgen cycloaddition, for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles. Keywords: azide–alkyne Huisgen cycloaddition; carbohydrates

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• ], gold-catalyzed azetidin-3-one formation [16], as well as various transition metal-mediated additions and cross-coupling reactions [17] represent further important reactions of propargylamines, providing the potential to form innovative peptidomimetics (Figure 2). Our attention has been focused on the

• ) Intramolecular Pauson–Khand reaction, R = (S)-tert-butylsulfinyl, R’ = CH2CH2OTBDPS [14]. b) Diels–Alder reaction, R = pTs, R’ = H, R’’ = Me [15]. c) Gold-catalyzed intramolecular reaction to azetidin-3-ones, R = tert-butylsulfonyl, R’ = aromatics, aliphatics [16]. d) Sonogashira cross-coupling, R = tert

Is the tungsten(IV) complex (NEt₄)₂[WO(mnt)₂] a functional analogue of acetylene hydratase?

• Matthias Schreyer and
• Lukas Hintermann

Beilstein J. Org. Chem. 2017, 13, 2332–2339, doi:10.3762/bjoc.13.230

• . More specifically, gold complex AuCl(PPh3) is not usually considered an alkyne hydration catalyst itself, but turns into a catalytically active gold(I) cation after activation with silver salt or Lewis acid [31][32][33][34]. Under the forcing microwave reaction conditions in aqueous methanol

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

• , 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

• NMR signals of gold and boron complexes 8 and 9 were observed at δ = 6.0 and 11.5 ppm, respectively. These results show that the electronic nature of the phosphorus atoms is similar to that of the oxidized species 4–7 (δ = 6.0–27.0 ppm). In the IR spectrum of 4 in KBr, a strong absorption for P=O

• electron-accepting properties. This red shift related to methylation of a phosphorus atom is in line with other earlier studies [10][18][33]. The fluorescence intensity of 7 (Ф = 67%) was as strong as that of phosphine oxide 4. The gold and boron complexes (8 and 9, respectively) showed contrasting

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• exchange procedure yields 47 that can then be fully dealkylated with NaI in acetone to produce the phosphonic acid disodium salt 48 [172] (Figure 17). Bromotrimethylsilane is nowadays the gold standard reagent to produce phosphonic acid from dialkyl phosphonate under mild conditions (usually at room

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

Beilstein J. Org. Chem. 2017, 13, 2157–2159, doi:10.3762/bjoc.13.215

• with gold salts, such as KAuBr4, which readily crystallize as fine needles [10]. Based on this finding, a new and environmentally friendly recovery process for gold from excavation material is under development. Significant progress was achieved in the functionalization of CDs through the

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• , N-alkylcarboxyspiropyrans have been tagged (via ester or amide linkage) to carbon nanotubes (e.g., for photocontrolled Zn2+ delivery in biological media [8]) and gold electrodes (for photoswitching the bioelectrocatalytic cascade of cytochrome c/cytochrome oxidase [9]), and attachment to

Total synthesis of elansolids B1 and B2

• Liang-Liang Wang and
• Andreas Kirschning

Beilstein J. Org. Chem. 2017, 13, 1280–1287, doi:10.3762/bjoc.13.124

• cuvette at l = 589 nm (Na D-line). The optical rotation is given in [° mL·g−1·dm−1] with c = 1 corresponding to 10 mg mL−1. Preparative HPLC was operated at a Merck Hitachi LaChrome HPLC (Pump L7150 or L7100, Interface D-7000, Diode Array Detector L-7450), respectively, at a Beckmann system Gold HPLC

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

• glycosylations have now even been described in materials chemistry. Here they provide an extremely efficient way to functionalize hydroxy-terminated self-assembled monolayers (SAM) on gold (Scheme 37). First the surface was incubated with divinyl sulfone (DVS) in a basic aqueous buffer (pH 11) followed by

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

• , Nanotechnology Lab., Via G. Fantoli 16/15, 20138 Milan, Italy 10.3762/bjoc.13.100 Abstract Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent

• presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design. Keywords

• : gold nanoparticles; glyco nanoparticles; glyconanomaterials; immunology; targeting; Introduction Carbohydrates are well recognized as crucial biomolecules for their capability to produce an enormous number of biocodes which are translated into their ability to promote or suppress a plethora of

First total synthesis of kipukasin A

• Chuang Li,
• Haixin Ding,
• Zhizhong Ruan,
• Yirong Zhou and
• Qiang Xiao

Beilstein J. Org. Chem. 2017, 13, 855–862, doi:10.3762/bjoc.13.86

• subsequent Vorbrüggen glycosylation, the protecting group could be removed smoothly in the presence of 5 mol % Ph3PAuOTf in dichloromethane to provide kipukasin A in high yield and regioselectivity. Keywords: gold catalysis; kipukasin A; marine nucleoside; total synthesis; Vorbrüggen glycosylation

• , ester protection is preferred for Vorbrüggen glycosylations in nucleoside syntheses. Very recently, ortho-alkynylbenzoate was successfully developed by our group as neighboring participation group to synthesize 2’-modified nucleosides [24], which could be removed smoothly in the presence of gold(I

A practical and efficient approach to imidazo[1,2-a]pyridine-fused isoquinolines through the post-GBB transformation strategy

• Taofeng Shao,
• Zhiming Gong,
• Tianyi Su,
• Wei Hao and
• Chao Che

Beilstein J. Org. Chem. 2017, 13, 817–824, doi:10.3762/bjoc.13.82

• synthesis of the biologically intriguing imidazo[1,2-a]pyridine-fused isoquinoline systems from readily available starting materials was achieved through the Groebke–Blackburn–Bienaymé reaction followed by a gold-catalyzed cyclization strategy. The synthetic approach is characterized by mild reaction

• acetylene unit may then undergo a sequential 6-exo-dig cyclization/retro-ene reaction to form the desired imidazo[1,2-a]pyridine-fused isoquinoline 6a. The cyclization reaction could be realized with the aid of silver or gold catalysts [51][52]. With this idea in mind, we commenced our studies by

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• then effectively coupled to hyaluronate (a long-chain polymer containing repeating disaccharide units of glucuronate-β1->3-N-acetylglucosamine) stabilised gold nanoparticles (AuNPs) and used as a sensitive and selective probe to monitor hyaluronidase enzymatic activity, which is an enzyme that breaks

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

• Surface, UMR CNRS 7197, 4 place Jussieu, 75005 Paris, France Université de Nantes, CNRS, CEISAM, UMR 6230, Faculté des Sciences et des Techniques, rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France 10.3762/bjoc.13.64 Abstract Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces

• contact angle (WCA) measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Keywords: gold surfaces; hydrolysis; IRRAS; reversibility; SAM; sulfamide; XPS; Introduction Self-assembled monolayers (SAMs) have raised considerable

• 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

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

• well as the molecular structures of the reactants used in the described reaction. We repeated the described reaction cycle 20 times to obtain CMPs thin films on functionalized gold wafers. Characterization of CMP thin films We characterized the reaction using infrared reflection absorption spectroscopy

• (methyl methacrylate) (PMMA). Upon substrate dissolution, we transferred the PMMA stabilized CMP thin film to a fresh gold substrate. After drying, we dissolved the PMMA layer in acetone, leaving only the CMP thin film. We then investigated the thickness of the film by an atomic force microscope (AFM

• -methylpropan-1-one), iodine and potassium iodide were purchased from Sigma-Aldrich. TPM-SH [30] and TPM-alkyne [31] were synthesized as described in the literature. Substrates: The sacrificial substrate consists of a 150 nm gold film on mica. For analytical measurements, we transferred the membrane to a Si(100

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• known as A3 coupling reaction, remains the most common and straightforward method for the synthesis of propargylamine. The A3 coupling reaction is reported under transition-metal-catalyzed conditions using copper [12][17][18][19], gold [17][20][21], silver [17][22], zinc [17][23], nickel [24], iron [25

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

Computational methods in drug discovery

• Sumudu P. Leelananda and
• Steffen Lindert

Beilstein J. Org. Chem. 2016, 12, 2694–2718, doi:10.3762/bjoc.12.267

• poses by looking at steric overlaps was published in the 1980s [129]. Ever since then many docking algorithms have been developed [130][131][132][133][134][135]. Popular molecular docking programs include Glide [131], Fred [136], AutoDock3 [137], AutoDock Vina [134], GOLD [138] and FlexX [139

• function that combines knowledge-based and empirical scoring functions [134]. GOLD uses a force-field based scoring function and allows the ligand to be fully flexible. It allows target side chain flexibility to be taken into account. FlexX is an incremental fragment-based docking algorithm where the

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• .12.264 Abstract The mesomeric betaine imidazolium-1-ylphenolate forms a borane adduct with tris(pentafluorophenyl)borane by coordination with the phenolate oxygen, whereas its NHC tautomer 1-(2-phenol)imidazol-2-ylidene reacts with (triphenylphosphine)gold(I) chloride to give the cationic NHC complex [Au

• adduct displays two different conformers in the unit cell which differ inter alia in the torsion angles around the Nimidazole–Cphenol bonds [−53.32(16)° vs 114.12(13)°] and the Cphenyl–O bonds [49.43(17)° vs −15.29(18)°] (Figure 2). A gold complex of the N-heterocyclic carbene tautomer 6B can be obtained

• on reaction with (triphenylphosphine)gold(I) chloride in boiling anhydrous THF under a nitrogen atmosphere, under which conditions the colorless gold complex [Au(6B)2][Cl] (9) is formed in 60% yield (Scheme 1). The protons of the OH resonate at δ = 10.34 ppm in DMSO-d6, and the 13C NMR chemical shift

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

• well as solvent impurities increase synthesis and purification costs and time. Selectively per-6-thiolated CDs are also used in gold nanoparticle chemistry, particularly in electrochemical sensors [17]. Thiourea (TU) is one of the best precursors of those CDs because as the halogen is exchanged to the

Enduracididine, a rare amino acid component of peptide antibiotics: Natural products and synthesis

• Darcy J. Atkinson,
• Briar J. Naysmith,
• Daniel P. Furkert and
• Margaret A. Brimble

Beilstein J. Org. Chem. 2016, 12, 2325–2342, doi:10.3762/bjoc.12.226

• reaction site and poor compatibility of the cyclic guanidine motif with Lewis acids. Initial attempts to glycosylate cyclic guanidine 91 using an array of donors under Lewis acidic or basic conditions failed to provide access to N-mannosylguanidine 92 (Scheme 18). However, gold(I) mediated [71] N

Tunable microwave-assisted method for the solvent-free and catalyst-free peracetylation of natural products

• Manuela Oliverio,
• Paola Costanzo,
• Monica Nardi,
• Carla Calandruccio,
• Raffaele Salerno and
• Antonio Procopio

Beilstein J. Org. Chem. 2016, 12, 2222–2233, doi:10.3762/bjoc.12.214

• carrier gas) and by an DSQ II mass detector. Chromatography was performed using a Thermo Scientific Dionex Ultimate 3000 RS, injecting directly onto a Thermo Scientific Hypersil Gold C18 column (50 × 2.1 mm, 1.9 µm particle size), equilibrated in 95% solvent A (0.1% aqueous solution of formic acid), 5

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

• to form self-assembled monolayers on gold [69][70][71] as well as on zinc and iron oxide surfaces [72]. Conceptually, thienyl-bridged oligophenothiazines can be considered as a novel type of structurally well-defined electron-rich oligophenothiazine–thiophene hybrids (Figure 1). Thereby, the strong

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291

• Peng Zhang,
• Xiao-Ming Li,
• Xin-Xin Mao,
• Attila Mándi,
• Tibor Kurtán and
• Bin-Gui Wang

Beilstein J. Org. Chem. 2016, 12, 2012–2018, doi:10.3762/bjoc.12.188

• an Optical Activity AA-55 polarimeter. UV spectra were measured by a Lengguang Gold S54 photometer. ECD data were collected using JASCO J-715 or J-810 spectropolarimeters. NMR data were recorded on a Bruker Avance 500 MHz spectrometer with TMS as internal standard. Low and high resolution ESI-mass