Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• with a similar substitution pattern. In the myxobacterial metabolites an E-configuration was found at the benzylidene unit, whereas the nostoclides and cyanobacterin have a Z-configuration. Only the anhydro form of cyanobacterin was found to isomerize from the Z- to the E-configured isomer in organic

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• -diaryl-2,4,6-trimethylpyridines P6. In this study we report on the synthesis of a series of 3,5-diaryl-2,4,6-trimethylpyridines P6 (4–29) with substitution pattern at the phenyl ring as present in the most popular amphetamine-type drugs [23][27][34][35][36] (4-MeO, 4-MeS, 4-F, 4-Me, 3,4-OCH2O). We also

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

• including S. aureus and E. faecalis strains, with best results obtained for 88 (Figure 8). Evaluation of the inhibition of lipid II formation revealed the importance of the substitution pattern of the terminal amino acid. In 2010 and 2011, Ichikawa, Matsuda et al. published SAR studies with a range of

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

•  2, path a) [10]. This approach is generally lengthy, not flexible, and the substitution pattern highly depends on the availability of the starting materials. Recently, advances have been made to address some of these issues encountered in the synthesis of carbon-substituted piperazines [11]. For

Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions

• José M. Andrés,
• Miriam Ceballos,
• Alicia Maestro,
• Isabel Sanz and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2016, 12, 628–635, doi:10.3762/bjoc.12.61

• thiourea I [30] onto sulfonylpolystyrene resin leading to catalysts II–V (Figure 1), which differ in the length of the diamine linker or in the substitution pattern of the nitrogen in the sulfonamide. These materials, and the related unsupported thiourea VI, have been previously tested as excellent

• conditions, supported catalyst V, which differs from IV in the substitution pattern of the sulfonamide, was the best catalyst for the addition of both 2a and 3a to nitrostyrene, yielding products 4aa and 5aa, respectively, in much better yield maintaining the stereoselectivity in shorter reaction time

Antibiotics from predatory bacteria

• Juliane Korp,
• María S. Vela Gurovic and
• Markus Nett

Beilstein J. Org. Chem. 2016, 12, 594–607, doi:10.3762/bjoc.12.58

• four p-aminobenzoic acid (PABA)-derived moieties. The latter vary in their oxidation and substitution pattern, which may even comprise rare isopropoxy groups. The two unmodified PABA residues in compounds 919-1 and 919-2 are connected via an iso-β-methoxyasparagine or a β-methoxyasparagine unit

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• coupling) and ring contracting reactions. The choice of tactic is dependent on the individual substitution pattern of the target compound. However, many of the presented strategies rely on long synthetic sequences that cannot provide large amounts of synthetic material which is required for further

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• the substitution pattern of starting materials (substituted arylhydrazines and cyclohexanones) and is therefore useful mainly for the synthesis of symmetrically or unsubstituted derivatives [16][17]. Recently, our research group described the synthesis of tetrahydrocarbazole derivatives by Diels–Alder

• of these compounds. In particular, the dependence upon the substitution pattern at nitrogen and at the outer-ring double bond, highlighted the need to select the appropriate promoter for each desired transformation. Examples of drugs embodying unnatural amino acids. Examples of biologically active

Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2015, 11, 1944–1949, doi:10.3762/bjoc.11.210

• [15]. The substitution pattern of the indole substrate can have a significant effect on chemo- and regioselectivity. Electron-rich indoles typically give selective alkylation at the C3 position in the absence of a preexisting C3-substituent. In the presence of a C3-substituent, the alkylation is

• substitution pattern of an indole substrate, particularly in the 2- and 3-position, can have a significant effect on the reactivity and selectivity. The reaction gave a good yield (70%) of the 4-substituted quinoline carboxylate, demonstrating that a substituent in indole’s 3-position was tolerated well. The

[2.2]Paracyclophane derivatives containing tetrathiafulvalene moieties

• Laura G. Sarbu,
• Lucian G. Bahrin,
• Peter G. Jones,
• Lucian M. Birsa and
• Henning Hopf

Beilstein J. Org. Chem. 2015, 11, 1917–1921, doi:10.3762/bjoc.11.207

• recent report has appeared concerning the synthesis of a [2.2]paracyclophane doubly substituted by a dimeric tetrathiafulvalene in a pseudo-ortho substitution pattern [10]. This compound exhibited novel chiroptical properties. Prompted by these observations, we decided to investigate the synthesis of a

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• popularity of homogeneous PRCs is due to their ease of synthesis and stability as well as their excellent photoredox properties. Furthermore, they can be activated by visible light, precluding the requirement for specialized irradiation setups, and their reactivity can be tuned by altering the substitution

• pattern on the ligands and by changing the metal. In the case of the prototypical PRC, Ru(bpy)32+, absorption of a photon generates the long lived triplet species *Ru(bpy)32+ that can act both as a reductant and an oxidant. Electron transfer to an acceptor molecule A generates the A–• radical anion

Latent ruthenium–indenylidene catalysts bearing a N-heterocyclic carbene and a bidentate picolinate ligand

• Thibault E. Schmid,
• Florian Modicom,
• Adrien Dumas,
• Etienne Borré,
• Loic Toupet,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 1541–1546, doi:10.3762/bjoc.11.169

• , under these modified conditions the desired complex 4a could be prepared in a clean manner with an improved 62% isolated yield. Given the importance of the substitution pattern of the chelating [N–O] ligand, X-ray diffraction analysis unambiguously confirmed the structure of complex 4a, which displayed

An intramolecular C–N cross-coupling of β-enaminones: a simple and efficient way to precursors of some alkaloids of Galipea officinalis

• Hana Doušová,
• Radim Horák,
• Zdeňka Růžičková and
• Petr Šimůnek

Beilstein J. Org. Chem. 2015, 11, 884–892, doi:10.3762/bjoc.11.99

• -Diketones 4 were obtained using tert-butoxide or tert-pentoxide mediated Claisen condensation of esters 5 with the appropriate acetophenones 6a–d (Scheme 5, step c). The substitution pattern on compounds 6 was chosen so that the final products 1 are the precursors for the synthesis of galipinine, galipeine

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• summary, a bulky terminal substitution pattern in the allylic bromide reactant is thus an important factor in determining the eventual main product outcomes after N-monoallylation. Mechanistic discussions The short reaction times suggest the initial formation of monoallylated products followed by a second

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• ]. Toxicity of β-CD can be minimized by derivatisation [11][12]. Both, hydroxypropyl-β-CD (HP-β-CD) and sulfobutyl-β-CD are less toxic than β-CD, but they are less defined due to a statistical substitution pattern [13]. HP-β-CD often shows a reduced binding potential compared to β-CD [2][14]. On the other

A one-pot multistep cyclization yielding thiadiazoloimidazole derivatives

• Debabrata Samanta,
• Anup Rana,
• Jan W. Bats and
• Michael Schmittel

Beilstein J. Org. Chem. 2014, 10, 2989–2996, doi:10.3762/bjoc.10.317

• found that the product was produced in slightly lower yields of 42% and 55%, respectively. Using the optimized conditions (Table 1, entry 3), we prepared both benzyl (2b, 79%) and cyclohexyl (2c, 83%) substituted 1,2,4-thiadiazoles as representatives for a substitution pattern with various alkyl

• carbodiimide and thiourea units under in situ conditions. The product structure was confirmed by single crystal X-ray analysis in the solid state. The substitution pattern (aryl, benzyl, sec-alkyl) may be varied easily to achieve potentially biologically active compounds with interesting properties. The free

Synthesis of uniform cyclodextrin thioethers to transport hydrophobic drugs

• Lisa F. Becker,
• Dennis H. Schwarz and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 2920–2927, doi:10.3762/bjoc.10.310

• anaesthesia. Keywords: active pharmaceutical ingredient; binding constant; cyclodextrin; derivatization; gas chromatography; sevoflurane; substitution pattern; Introduction Cyclodextrins (CDs) are cyclic oligomers of α-1,4-linked glucose units. Those CDs consisting of 6, 7, and 8 glucose units are called α

• (Figure 1) showed a rather broad molecular weight distribution typical for CD derivatives with statistical substitution pattern. On the other hand, nearly uniform CD derivatives were synthesized by regioselective deprotonation of all 2-OH positions with NaH in DMF solution according to Tian and D’Souza

• MS of 3b1 (Figure 1) showed a significantly lower polydispersity than 2b1. Also the 1H NMR spectrum of 3b1 was much better resolved than the one of the statistical derivative 2b1 due to its homogenous substitution pattern and uniform lengths of the oligoethylene oxide groups (Figure 2). All β-CD

Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

• Joscha Vollmeyer,
• Friederike Eberhagen,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2014, 10, 2774–2782, doi:10.3762/bjoc.10.294

• the role of intraannular substituents on the 2D supramolecular surface patterns of macrocyclic compounds. Therefore, in addition to the concentration-driven conformational polymorphism that is yet attributed to a distinct extraannular substitution pattern as discussed above, we evaluate the role of

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• under ambient conditions and UV-illumination is presented in Figure 2. The effect of the substitution pattern of the BODIPY core with fluorene arms (either at the α- or β-positions) on the optical properties of the materials can be observed with the naked eye. The compounds of the Y-Bn (n = 1–4) series

Facile synthesis of 1H-imidazo[1,2-b]pyrazoles via a sequential one-pot synthetic approach

• András Demjén,
• Márió Gyuris,
• János Wölfling,
• László G. Puskás and
• Iván Kanizsai

Beilstein J. Org. Chem. 2014, 10, 2338–2344, doi:10.3762/bjoc.10.243

• imidazo[1,2-b]pyrazole core is definitely an attractive synthetic target, in view of its noteworthy pharmacological potential, which is strongly affected by the ring substitution pattern and the level of ring saturation. Among others, anti-inflammatory [37][38], antiviral [28][39] and antidiabetic [40

• simple, green access to highly substituted 1H-imidazo[1,2-b]pyrazoles with easily variable substitution pattern and does not require complex purification techniques. The conventional GBB-3CR. Plausible products 6A–H. Synthesis of 6 via the sequential one-pot method. Solvent and catalyst screen of the GBB

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• substitution pattern of benzoates we intended to shift the electrochemical reduction potentials of the substances into a region that could be accessed by common visible light photocatalysts. The substituents should be as inert as possible in order not to interfere with the photochemical reaction itself

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• , unfortunately, no clear trend observed for the oxidation potentials based on the substitution pattern of the aryl moieties, although both oxidations appear somewhat easier for pentacene 3f as a result of the two electron-donating methoxy groups attached to the pendent phenyl ring. Aryl-substituted pentacenes 3a

• –k each show one reversible reduction event in a rather narrow range of −1.59 to −1.68 V. Similar to that observed for the oxidation potentials, there is no obvious trend that can be identified in the reduction potentials based on substitution pattern, aside from the observation that the silyl

• change the electronic properties of the pentacene skeleton itself. Aryl-substitution pattern does however, have a considerable effect on solid-state arrangement of the molecules, and X-ray crystallographic analysis afforded insight on the packing arrangements of the synthesized pentacenes. In spite of

Chemistry of polyhalogenated nitrobutadienes, 14: Efficient synthesis of functionalized (Z)-2-allylidenethiazolidin-4-ones

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Mimoza Gjikaj and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2014, 10, 1638–1644, doi:10.3762/bjoc.10.170

• molecules were incorporated into the final product, whereas two additional equivalents were consumed capturing hydrochloric acid. In this way, the 1H-pyrazole 27 with an exceptional substitution pattern was obtained in 64% yield. The same reaction was applied to 5-arylmethylidene-thiazolidin-4-one 25 which

Triazol-substituted titanocenes by strain-driven 1,3-dipolar cycloadditions

• Andreas Gansäuer,
• Andreas Okkel,
• Lukas Schwach,
• Laura Wagner,
• Anja Selig and
• Aram Prokop

Beilstein J. Org. Chem. 2014, 10, 1630–1637, doi:10.3762/bjoc.10.169

• started our investigation with the preparation of azide-substituted cationic titanocenes. To this end, the titanocene carboxylates 1–3 shown in Figure 1 were employed as substrates because their substitution pattern should allow a first simple assessment of structure–activity relationships. The compounds

• through 1,3-dipolar cycloaddition markedly changes the activity of our titanocenes as a function of the substitution pattern. The most active complexes are highlighted in Figure 3. Gratifyingly, 18, together with a ketone-substituted titanocene, displays the highest activity against the BJAB cell line of

A promising cellulose-based polyzwitterion with pH-sensitive charges

• Thomas Elschner and
• Thomas Heinze

Beilstein J. Org. Chem. 2014, 10, 1549–1556, doi:10.3762/bjoc.10.159

• . While polyzwitterions based on N-functionalized chitosan [14][15] or 6-desoxy-6-aminocelluloses [16] are composed like synthetic polybetaines, a few cellulose-based zwitterions are described where the isoelectric point and the properties in solution could be tuned by varying the substitution pattern [17