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

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

• 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

• -terminated SAM with an aldehyde in solution or the condensation of an aldehyde-terminated SAM with an amine in solution [19]. These surfaces were stable in water but readily erased by acid-catalyzed hydrolysis at pH 3. The propensity of imines to be hydrolyzed under acidic conditions has also been harnessed

• gold based on the sulfamide chemistry and to partially regenerate the amino SAM. The surface modification process is studied by water contact angle measurements (WCA), Fourier transform infrared reflection absorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). Results and

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

• ; spring constant: 3.5 N/m). Self-assembled monolayer (SAM) preparation: For SAM formation, a clean gold substrate (2.2 cm × 2.2 cm) was rinsed with absolute ethanol and then immersed in a solution of S-[11-oxo-11-(propargylamino)undecyl] thioacetate (AcSC10H20C(O)NHCH2C≡CH) (with a concentration of 1 mmol

• added to the SAM coated substrate and stirred gently to ensure proper mixing. Then the mixture was exposed to 365 nm UV-light for 3 minutes. Afterwards, the substrate was rinsed with dry THF. Subsequently, 1 mL of TPM-alkyne solution and 0.5 mL of the photoinitiator solution were added to the substrate

From supramolecular chemistry to the nucleosome: studies in biomolecular recognition

• Marcey L. Waters

Beilstein J. Org. Chem. 2016, 12, 1863–1869, doi:10.3762/bjoc.12.175

• work of Dennis Dougherty [2], Francois Diederich [3], Sam Gellman [6], Eric Kool [5] and Jeremy Sanders [4] to name a few working in the area at the time (Figure 3). I was particularly interested in addressing whether aromatic interactions provided a degree of selectivity that is not possible with

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

• Vincent M. Rotello

Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161

• Sam Danishefsky and facilitating my next move. Moving to Legoland Sorting out what I wanted to do after grad school was a bit of a challenge. In those days I knew I wanted to be an academic, but what I wanted to do scientifically was an open question. I started thinking about proposals for

Biosynthesis of oxygen and nitrogen-containing heterocycles in polyketides

• Franziska Hemmerling and
• Frank Hahn

Beilstein J. Org. Chem. 2016, 12, 1512–1550, doi:10.3762/bjoc.12.148

• mechanism is reminiscent of the formation of a tetrahydropyridine ring by the berberine bridge enzyme in plant alkaloid biosynthesis. It starts with S-adenosyl-L-methionine (SAM)-dependent methylation of the secondary hydroxy group in 81 by the O-methyltransferase Leu14 (Scheme 14a) [71][72][73][74

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

• thioester acyl–enzyme intermediate that is then attacked by Cys28 of AgrD to generate a 16-membered thiolactone [120] (Figure 9). Radical SAM-catalysed oxidative cross-linking The majority of characterised cyclic RiPPs are generated by standard ionic reactions. In contrast, radical mechanisms permit

• reactions between unactivated atoms [122], and this exotic chemistry is employed in a number of RiPP cyclisations. In each case, cyclisation is catalysed by members of the SPASM protein family [123][124]. These are radical SAM (S-adenosylmethionine) proteins that contain two [4Fe–4S] binding domains, and

• , and a mechanism was proposed by the Marahiel group based following detailed in vitro studies [26] (Figure 10A). The first [4Fe–4S] cluster accepts an electron from an external source to generate an active reduced form. This electron is transferred to a coordinated SAM, which is reductively cleaved to

Muraymycin nucleoside-peptide antibiotics: uridine-derived natural products as lead structures for the development of novel antibacterial agents

• Daniel Wiegmann,
• Stefan Koppermann,
• Marius Wirth,
• Giuliana Niro,
• Kristin Leyerer and
• Christian Ducho

Beilstein J. Org. Chem. 2016, 12, 769–795, doi:10.3762/bjoc.12.77

• (SAM), and the resultant intermediate 102 is decarboxylated to provide diamine 103. Attachment of the aminoribosyl moiety (which is supposedly also derived from uridine (1) over several enzymatic steps) finally affords the aminopropyl-substituted 5'-O-aminoribosylated GlyU core structure 104

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• that he himself described as “people that you will hear from in the future, not people who will disappear into the woodwork.” Indeed, my labmates during the period from 1979 to 1983 included Jik Chin, Robert Corcoran, Tony Czarnik, Sam Gellman, Don Hilvert, Uday Maitra, Dave Okrongley, Russ Petter

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• branched polyketides at the α-position of the growing chain include the usage of different elongation units such as methylmalonyl-CoA, or methylation of the nucleophilic α-position by S-adenosyl methionine (SAM) [21]. Branching in the β-position is less common and proceeds through a β-aldol attack of an

• to different cyclic peptides from Photorhabdus and Xenorhabdus species [42] and for activity testing of heterologously expressed SAM-epimerases from various bacteria [43]. In a follow-up study the recently discovered NRPS product kollosin A (16, Figure 4) was investigated. This pentadecapeptide is

• incorporation of labeled Gly into the methyl group was rationalized by glycine degradation, directing the labeling via tetrahydrofolate and SAM into aspirochlorine biosynthesis. The conversion of the Phe residue to Gly may proceed through either oxidative C–C bond cleavage or a retro-aldol reaction in 18, in

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• the results are summarised in Table 2. The OFETs fabricated using only OTS as the SAM from a chloroform solution show an average saturation hole mobility of 1.35 × 10−5 cm2 V−1 s−1 and an ON/OFF ratio of 101. However, the use of both PFBT and OTS SAMs and a chloroform solution of compound 2 results in

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• approaches are taken to achieve surface modification as illustrated in Figure 1. The first involves incorporating pre-functionalised alkylsilanes/alkylthiols carrying functional groups (FG) to generate the SAM directly, whereas the second approach involves chemical modification of a pre-assembled monolayer

• carrying reactive groups (RG), as a means to introduce the SAM carrying the FGs [8]. Both approaches present challenges. In the former the desired functionality (FG) requires to be robust and orthogonal in reactivity to the chemistry involved in securing the substrate to the organic film (e.g., FG-Alkyl

• -SiCl3 and silicon substrate). In the latter chemical modification of the reactive groups of the pre-coated SAM has to be efficient enough such that a reasonable conversion can be obtained, with chemical specificity and lack of surface degradation. In this respect ‘click’ reactions have become attractive

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• ]. Our group has shown that also simple carbohydrate microarrays can be conveniently prepared by μCP if reactive glycosides are printed on a suitable target self-assembled monolayer (SAM) [31][32]. Amongst others, we reported carbohydrate microarrays fabricated by cycloaddition of alkynes on azide

• Supporting Information File 1. Further information on the printing process was obtained from X-ray photoelectron spectroscopy (XPS) of Si-wafers functionalized with an epoxide-terminated SAM and printed with NANA ink using a PEG coated flat stamp (see Figure S3 and Figure S4 in Supporting Information File 1

• ). While nearly no N(1s) signal was detected in the epoxide-terminated SAM, a clear N(1s) signal can be observed when the NANA ink is printed. The C(1s) peak shows a splitting into the C–C (285 eV), C–O (287 eV), C=C, C=O and residual epoxide C–O signals (289 eV) as expected for the NANA-terminated SAM [52

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• global chloroform emissions [12]. The introduction of halogens into natural products is catalysed by various known types of enzymes [13][14], including the FADH2-dependent halogenases [15], α-ketoglutarate/Fe2+-dependent halogenases [16], SAM-dependent halogenases [17][18], and vanadium-dependent

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• ) units. The remaining methyl groups are believed to be installed by S-adenosyl methionine (SAM). An intramolecular Aldol condensation generates the pyrrolinone 62, which reacts via an [4 + 2]-cycloaddition to prochaetoglobosin I (63) [56]. Recently, gene disruption studies of Chaetomium globosum revealed

• –Spengler reaction of dopamine (99) with 4-hydroxyphenylacetaldehyde (100), both derived from L-tyrosine (98) (Scheme 11). After oxidation and O-methylation, which is carried out by S-adenosylmethionine (SAM), (S)-reticuline (101) is obtained. Oxidation of the N-methyl group to the iminium ion and

New tridecapeptides of the theonellapeptolide family from the Indonesian sponge Theonella swinhoei

• Annamaria Sinisi,
• Barbara Calcinai,
• Carlo Cerrano,
• Henny A. Dien,
• Angela Zampella,
• Claudio D’Amore,
• Barbara Renga,
• Stefano Fiorucci and
• Orazio Taglialatela-Scafati

Beilstein J. Org. Chem. 2013, 9, 1643–1651, doi:10.3762/bjoc.9.188

• dell’Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy Faculty of Fishery and Marine Science, Sam Ratulangi University, Manado, Indonesia Dipartimento di Medicina Clinica e Sperimentale, Università di Perugia, Via Gambuli 1, 06132 Perugia, Italy 10.3762/bjoc.9.188 Abstract

• This work was supported by the EU project Bluegenics (Grant 311848) and by the University of Naples Federico II (MOU with Universitas Sam Ratulangi, Manado). NMR spectra were recorded at the CSIAS, Centro Interdipartimentale di Analisi Strumentale, Department of Pharmacy, University of Naples Federico

Influence of cyclodextrin on the solubility and the polymerization of (meth)acrylated Triton^® X-100

• Melanie Kemnitz and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2176–2183, doi:10.3762/bjoc.8.245

• Acros Organics. They were dried in a microwave drying system SAM 255 (CEM). Methacryloyl chloride (Fluka), acryloyl chloride (Fluka), triethylamine (Acros Organics), AIBN (Sigma-Aldrich), VA-044 (Wako Chemicals) and DMF (VWR) were used as received. Measurements Isothermal titration calorimetry

Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

• Rick C. White,
• Benny E. Arney Jr. and
• Heiko Ihmels

Beilstein J. Org. Chem. 2012, 8, 1208–1212, doi:10.3762/bjoc.8.134

• Rick C. White Benny E. Arney Jr. Heiko Ihmels Department of Chemistry, Sam Houston State University, Huntsville, TX 77341, USA Department of Chemistry, Universität Siegen, Adolf-Reichwein-Str. 2, 57068 Siegen, Germany 10.3762/bjoc.8.134 Abstract The photochemistry of a phenyl and 1,2-diphenyl

Mutational analysis of a phenazine biosynthetic gene cluster in Streptomyces anulatus 9663

• Orwah Saleh,
• Katrin Flinspach,
• Lucia Westrich,
• Andreas Kulik,
• Bertolt Gust,
• Hans-Peter Fiedler and
• Lutz Heide

Beilstein J. Org. Chem. 2012, 8, 501–513, doi:10.3762/bjoc.8.57

• derivatives. It has been reported that, likewise, PhzM from P. aeroginosa was not active when incubated with PCA and SAM alone; methylating activity was only detected when the hydroxylase PhzS and its cofactor NADH were also included in the incubation [23][24]. The endophenazine biosynthetic gene cluster from

Synthesis of mesomeric betaine compounds with imidazolium-enolate structure

• Nina Gonsior,
• Fabian Mohr and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 390–397, doi:10.3762/bjoc.8.42

• functionalized polymer networks and oligomers, which were stable at temperatures up to 300 °C and 200 °C, respectively. Experimental Materials. Randomly methylated (1.8) β-cyclodextrin (m-β-CD) was obtained from Wacker-Chemie GmbH (Burghausen, Germany). Prior to use, m-β-CD was dried in a CEM Sam 255 microwave

Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

• Jeroen S. Dickschat,
• Hilke Bruns and
• Ramona Riclea

Beilstein J. Org. Chem. 2011, 7, 1697–1712, doi:10.3762/bjoc.7.200

• for internal methyl branches in various chain positions, while the methyl ester function is derived from S-adenosyl methionine (SAM). Keywords: actinomycetes; FAMEs; fatty acid biosynthesis; GC–MS; volatiles; Introduction Lipids in general, and particularly fatty acids (FAs), belong to the most

• elongation units, and occur due to the logic of FA biosynthesis in even-numbered positions of the FA carbon chain. An alternative mechanism leading to the same methyl branching pattern is well-known from polyketide biosynthesis and involves the incorporation of a malonyl-CoA unit followed by SAM-dependent

• building blocks for the biosynthesis of these methyl esters are highlighted in bold and by use of a colour code in Figure 1. For the methyl 2-methylalkanoates and -alk-2-enoates from Chitinophaga, the origin of the methyl group from S-adenosyl methionine (SAM, purple) and of the 2-methyl groups from

Marilones A–C, phthalides from the sponge-derived fungus Stachylidium sp.

• Celso Almeida,
• Stefan Kehraus,
• Miguel Prudêncio and
• Gabriele M. König

Beilstein J. Org. Chem. 2011, 7, 1636–1642, doi:10.3762/bjoc.7.192

• -derived methyl group 8-CH3 in the methyl-orsellinic acid precursor would be replaced by an ethyl group. Thus, the biosynthesis seems to require either a propionate starter unit (see C in Figure S15; Supporting Information File 1) or a methylation (e.g., via a SAM-dependent methyl-transferase) at C-8 (see

Natural product biosyntheses in cyanobacteria: A treasure trove of unique enzymes

• Jan-Christoph Kehr,
• Douglas Gatte Picchi and
• Elke Dittmann

Beilstein J. Org. Chem. 2011, 7, 1622–1635, doi:10.3762/bjoc.7.191

• ]. Unique features of the cluster include a putative GCN5-related transferase, which is suggested to transfer three methyl groups from S-adenosyl-methionine (SAM) to malonyl-CoA to yield the tert-butyl terminus of apratoxin. The cluster further encodes a series of proteins resembling an HCS-like gene

Syntheses and properties of thienyl-substituted dithienophenazines

• Annemarie Meyer,
• Eva Sigmund,
• Friedhelm Luppertz,
• Gregor Schnakenburg,
• Immanuel Gadaczek,
• Thomas Bredow,
• Stefan-S. Jester and
• Sigurd Höger

Beilstein J. Org. Chem. 2010, 6, 1180–1187, doi:10.3762/bjoc.6.135

• different thiophene substituents. Currently we investigate the electrooptical properties of these compounds and similar derivatives. In addition, for one of the compounds a SAM on HOPG could be observed. a) Absorption (solid lines) and emission (dotted lines) spectra of compounds 12a (blue), 13 (red), 14

Catalysis: transition-state molecular recognition?

• Ian H. Williams

Beilstein J. Org. Chem. 2010, 6, 1026–1034, doi:10.3762/bjoc.6.117

• an archetypal reaction in organic chemistry and an important process in biochemistry. Catechol-O-methyl transferase (COMT) catalyses methyl transfer from S-adenosylmethionine (SAM) to a catechol (Scheme 1), and this reaction manifests an unusually large inverse secondary kinetic isotope effect as

• compared with a model, uncatalysed reaction in solution: the isotope effect VCH3 /VCD3 = 0.83 ± 0.05 for methylation of 3,4-dihydroxyacetophenone with SAM at 37 °C catalysed by COMT was found [11] to be more inverse than the value of kCH3 /kCD3 = 0.97 ± 0.02 for methylation of methoxide ion by S

• 3,4-dihydroxyacetophenone with SAM at 37 °C catalysed by COMT. In contrast, we calculated kCH3 /kCD3 = 0.99 ± 0.16 for methylation of methoxide ion by S-methyldibenzothiophenium ion at 25 °C in methanol, as compared with the experimental value [12] of 0.97 ± 0.02. The computational results reproduce