Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B

• Danielle L. Paterson and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29

• reversibility of the ring closure and preferred formation of isomer 7a. Conclusion In conclusion, the first synthesis of the furo[2,3-b]chromene ring system found in hyperaspidinols A (1) and B (2) has been achieved. Analysis of the NMR of synthetic furo[2,3-b]chromenes 7a and 7b and comparison to the data of 1

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

• . All the oligomers of the Y-Bn (n = 1−4) series feature a reduction wave corresponding to the formation of a radical anion in the BODIPY core [36], but its position and reversibility varies for the different members of the family, being reversible and at a less negative potential for Y-B1 (E1/2 = −1.14

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• electrochemical study of the triads in the solid state was also analysed. Although a similar pattern of redox processes is observed for oxidation and reduction, the reversibility of these peaks is lost compared to the solution state studies due to the films dissolving in the electrolytic medium in their highly

Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

• Véronique Nardello-Rataj and
• Loïc Leclercq

Beilstein J. Org. Chem. 2014, 10, 2603–2622, doi:10.3762/bjoc.10.273

Host–guest-driven color change in water: influence of cyclodextrin on the structure of a copper complex of poly((4-hydroxy-3-(pyridin-3-yldiazenyl)phenethyl)methacrylamide-co-dimethylacrylamide)

• Nils Retzmann,
• Gero Maatz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2480–2483, doi:10.3762/bjoc.10.259

• and led to an increased usage of dyes in the field of optical recording media [8][9]. However, up to now, only little is known about the interactions of azo–metal chelate complexes in supramolecular structures with CD as a modulator for macromolecular effects. Few reports dealt with the reversibility

Photoswitchable precision glycooligomers and their lectin binding

• Daniela Ponader,
• Sinaida Igde,
• Marko Wehle,
• Katharina Märker,
• Mark Santer,
• David Bléger and
• Laura Hartmann

Beilstein J. Org. Chem. 2014, 10, 1603–1612, doi:10.3762/bjoc.10.166

• , demonstrating the reversibility of the systems. Finally, the thermal stability of Z-Azo-Gal(1,3)-3 in the buffer solution is quite high. Indeed, after 48 h at 25 °C only 12% of the Z-isomers converted back to the E-isomer (see Supporting Information File 1). The thermal stability of the trivalent Azo-Gal(1,3,5

End-group-functionalized poly(N,N-diethylacrylamide) via free-radical chain transfer polymerization: Influence of sulfur oxidation and cyclodextrin on self-organization and cloud points in water

• Sebastian Reinelt,
• Daniel Steinke and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 680–691, doi:10.3762/bjoc.10.61

• ) investigated in the present study were prepared via a free-radical instead of a living polymerization technique and had a relative low molecular weight, the optical transmission diagrams indicate a relatively sharp transition in a temperature range of 1 °C up to 2 °C as well as a good reversibility upon

• reversibility by addition of RAMEB-CD; Right: DLS measurements size distributions for RAMEB-CD (orange line), 9c (black line) and 9c plus 1 equiv RAMEB-CD (blue line). Schematic illustration of the micellar-like structures, its deformation upon addition of one equivalent RAMEB-CD and the influence on the cloud

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• temperature dependence of the main reaction product type obtained from dimethyl diazomalonate and 2,2,4,4-tetramethyl-3-thioxocyclobutanе-1-one as well as to verify reversibility of the thiocarbonyl ylide and 1,3-oxathiole interconversion, the calculations of the energy profile for the transformation of 1,3

• . The latter undergoes decomposition to the alkene 5e upon extrusion of disulfur S2. Similar mechanisms for the spontaneous desulfurization of oxathiiranes have been reported in a recent publication [27]. In order to verify the observed reversibility of the thiocarbonyl ylide 6e' and oxathiole 3e

• and TS2. At higher temperatures energetically more favorable thiirane 8e' becomes the main 1,3-electrocyclization product of thiocarbonyl ylide 6e'. The succeeding decomposition of thiirane 8e' produces alkene 5e and sulfur with evolution of 6.6 kcal·mol−1. Thus, the reversibility of the thiocarbonyl

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

• -dipolar cycloaddition. Carrying out the reaction at 180 °C in tetrahydrofuran provided a separable mixture of pyrrolidine isomers 241 and 242 (1:3.6). The undesired cycloadduct 242 could be equilibrated to 241 due to the reversibility of the reaction. Conversion to the β,γ-cyclohexenone 243 was

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• to prove the reversibility of cleavage and rebuilding of the disulfide functionality, polymer discs containing a fixed amount of 5.0 mol % CL 1 and various amounts of CL 2 were synthesized (samples 6). The amount of CL 2 was chosen as 1.0 mol % (6a), 2.5 mol % (6b) or 5.0 mol % (6c) to ensure form

• functionalities were cleaved or that other interactions, possibly of the thiol-bearing side chains, are involved. Nevertheless, the decrease of the G’ values shown for all samples proves the redox-responsive character of CL 1. The reversibility of cleavage and rebuilding of the cross-linking disulfide

Anodic coupling of carboxylic acids to electron-rich double bonds: A surprising non-Kolbe pathway to lactones

• Robert J. Perkins,
• Hai-Chao Xu,
• John M. Campbell and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2013, 9, 1630–1636, doi:10.3762/bjoc.9.186

• reversibility of the cyclization. Clearly, the use of basic reaction conditions with the acidic substrate led to dramatic mechanistic changes to our early, simplified view of the reactions. It is tempting to suggest that similar situations would arise with other acidic substrates. For example, would the

A simple, enaminone-based approach to some bicyclic pyridazinium tetrafluoroborates

• František Josefík,
• Markéta Svobodová,
• Valerio Bertolasi and
• Petr Šimůnek

Beilstein J. Org. Chem. 2013, 9, 1463–1471, doi:10.3762/bjoc.9.166

• substituents was easily synthesized. A mechanism of the formation of the pyridazinium salts is suggested. A partial drawback is the possibility of the formation of a mixture of products when using a different diazonium salt in each step due to a reversibility of the azo coupling. This can be suppressed by

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• experiments support the reversibility of these “rollover” reactions. The highly unsaturated species 55 is still reactive and can coordinate and decompose XMe2 molecules (X = S [128] and O [129]) and dehydrogenate alkanes [130]. Finally

Use of 3-[¹⁸F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

• Reik Löser,
• Steffen Fischer,
• Achim Hiller,
• Martin Köckerling,
• Uta Funke,
• Aurélie Maisonial,
• Peter Brust and
• Jörg Steinbach

Beilstein J. Org. Chem. 2013, 9, 1002–1011, doi:10.3762/bjoc.9.115

• towards attack by iodide forming 1,3-diiodopropane. The thereby-released thiocyanate anion reacts with concomitantly formed 7 to give 1,3-dithiocyanatopropane. The reversibility of the iodide/thiocyanate displacement has been reported previously [24] and alkyl thiocyanates can be quantitatively

The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

• Jiayang Li,
• Yi Kuang,
• Junfeng Shi,
• Yuan Gao,
• Jie Zhou and
• Bing Xu

Beilstein J. Org. Chem. 2013, 9, 908–917, doi:10.3762/bjoc.9.104

• decreasing of the pH value of the solution of 1b to 4.0 results in an opaque hydrogel (Figure 1B), which lacks thermal reversibility and turns into white precipitates when it is heated to about 60 °C. Additionally, the white and opaque color of the hydrogel suggests that 1b tends to form microcrystals [65

• solution of 4a becomes a stable semitransparent hydrogel (Figure 1H) after standing at room temperature and pH 7.2 overnight. Despite its thermal reversibility, 4a shows weak recovery properties. Compound 5a fails to form a hydrogel, likely due to the insufficient aromatic–aromatic interaction originating

• reversibility. As shown in Figure 2C and Figure 2D, both the hydrogels of 1d and 1f comprise uniform long nanofibers, whose average widths are 6–7 nm. The exceptional high density of nanofibers in the hydrogel of 1d likely originates from the relatively high concentration of 1d in the hydrogel. The hydrogel of

A versatile and efficient approach for the synthesis of chiral 1,3-nitroamines and 1,3-diamines via conjugate addition to new (S,E)-γ-aminated nitroalkenes derived from L-α-amino acids

• Vera Lúcia Patrocinio Pereira,
• André Luiz da Silva Moura,
• Daniel Pais Pires Vieira,
• Leandro Lara de Carvalho,
• Eliz Regina Bueno Torres and
• Jeronimo da Silva Costa

Beilstein J. Org. Chem. 2013, 9, 832–837, doi:10.3762/bjoc.9.95

• studied due to the low reactivity of neutral nucleophiles associated with the reaction reversibility [46][75][76]. Addition of methoxide anion to 2a–c led to the corresponding chiral 2-methoxy-1,3-nitroamine derivatives 9a–c in 70–90% yield (Table 1, entries 4–8). A high d.r. was obtained when shorter

• . On the other hand, the neat benzylamine addition, or in the presence of DBU (0.5 equiv) as promoter [84], to 2a,b was unsuccessful (Table 1, entries 14 and 15). This nonreactivity can be explained on the basis of the high tendency toward reversibility presented in conjugate additions of amines to

Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• reversibility of that deprotonation can be discounted. Sterically, that deprotonation is much more demanding than the hydrogen self-exchange, as Newman projections of the expected transition states show. With both reactions, there are four gauche interactions between methyl and a large group (iPr or N(iPr)2

A peptidic hydrogel that may behave as a “Trojan Horse”

• Nicola Castellucci,
• Giorgio Sartor,
• Natalia Calonghi,
• Carola Parolin,
• Giuseppe Falini and
• Claudia Tomasini

Beilstein J. Org. Chem. 2013, 9, 417–424, doi:10.3762/bjoc.9.44

• been reported [11]. In the gels, noncovalent, weak interactions between the individual LMWHG molecules hold the fibers together. The gel-forming characteristics of LMWHGs can be controlled by altering the strength of these interactions, as illustrated by the thermal reversibility of the gel–sol

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• selectivity (59:9 versus 56:17) for 4,5-fused system 5 over a 4,6-fused system 6. However, conversion in the microflow system was lower than that in the batch reactor [25]. This was later shown to be due to the reversibility of the cycloaddition to yield 5, whilst the reaction to yield 6 is irreversible. Thus

Cyclodextrin-induced host–guest effects of classically prepared poly(NIPAM) bearing azo-dye end groups

• Gero Maatz,
• Arkadius Maciollek and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 1929–1935, doi:10.3762/bjoc.8.224

• °C the DZ of 8 increased up to 21000 nm, but the values showed poor stability because of sedimentation. This means that 8 is able to form larger particles above the LCST, even resulting in precipitation [23]. However, the change of DZ showed a good reversibility upon cooling. The behavior can be

Hybrid super electron donors – preparation and reactivity

• Jean Garnier,
• Douglas W. Thomson,
• Shengze Zhou,
• Phillip I. Jolly,
• Leonard E. A. Berlouis and
• John A. Murphy

Beilstein J. Org. Chem. 2012, 8, 994–1002, doi:10.3762/bjoc.8.112

• inhibit the protonation of 3 by competing for protons. (Notably, in earlier studies on the reversibility of formation of imidazoline-based donors, Liu and Lemal inhibited dissociation by adding KH as base [43]). In the cyclic voltammetry case, 3 would be generated from disalt 38. As 3 starts to be

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

• Nicholas G. White and
• Paul D. Beer

Beilstein J. Org. Chem. 2012, 8, 246–252, doi:10.3762/bjoc.8.25

• caused a cathodic shift of the oxidation potential of 25 mV and a loss of reversibility, which may be indicative of an EC mechanism [14] (Figure 4). Further addition of TBA·Cl led to increasing cathodic perturbations of the Epa oxidation wave of up to 40 mV after five equiv. As noted with other ferrocene

• , 300, 400 and 500 mV s−1 were used in order to test for reversibility. Aliquots of TBA·Cl or TBA·BzO (as a 0.50 M solution of electrolyte solution) were added to the receptor solution, stirred and the cyclic voltammograms recorded at a scan rate of 100 mV s−1. Solid-state structure of 3 (left) and 4

Efficient, highly diastereoselective MS 4 Å-promoted one-pot, three-component synthesis of 2,6-disubstituted-4-tosyloxytetrahydropyrans via Prins cyclization

• Naseem Ahmed and
• Naveen Kumar Konduru

Beilstein J. Org. Chem. 2012, 8, 177–185, doi:10.3762/bjoc.8.19

• unsymmetrical tetrahydropyran derivatives in an economical manner. Moreover, it was observed that MS 4 Å might have a vital part in controlling the reversibility of the [3,3]sigmatropic rearrangement. Furthermore, cleavage of the 4-tosyl group under mild conditions afforded 4-hydroxytetrahydropyrans in high

Sexithiophenes as efficient luminescence quenchers of quantum dots

• Christopher R. Mason,
• Yang Li,
• Paul O’Brien,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2011, 7, 1722–1731, doi:10.3762/bjoc.7.202

• . The corresponding reduction process is also shifted from +0.56 V to +0.41 V. The second oxidation potential for 1b experiences a shift to lower values (1.04 V compared to 0.89 V), but the reversibility is diminished somewhat; ΔE2a–c (mV) 2b, 170 mV; 1b, 270 mV. The decrease in oxidation potentials 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

• least-squares fitting curve. Partial 1H NMR spectra (400 MHz) of ACAQ (5 mM) before and after the addition of Cd2+ and then incremental addition of cysteine in DMSO-d6. Proposed binding model of Cd2+–ACAQ with cysteine. Reversibility study. Emission spectra of Cd2+–ACAQ complex (5 μM) with 10 equiv L