Terminal lipophilization of a unique DNA dodecamer by various nucleolipid headgroups: Their incorporation into artificial lipid bilayers and hydrodynamic properties

• Emma Werz and
• Helmut Rosemeyer

Beilstein J. Org. Chem. 2015, 11, 913–929, doi:10.3762/bjoc.11.103

• 12-mer DNA sequence using the Avogadro or the RasMol software. Half of the diameter corresponds to the half axis, b. Because nucleic acids bind water molecules and are, therefore, covered by a hydration shell, 2.8 Å is added to the radius b which is the diameter of a water molecule. The mean value of

• experimental and the calculated diffusion coefficients (Table 5, last column) is 1.45 ± 0.09 on average. Our data are comparable with those reported by Fernandes et al. in 2002 [23], which was also determined for DNA 12mers (1.22 and 1.45 × 10−6 cm2 s−1). Hydration of the lipo-oligonucleotides In an aqueous

• environment, water molecules form a hydration shell around the nucleic acid. Consequently, the surface of the nucleic acid chain is smoothed, and the partial volume of the hydrated molecule (Vhyd) is increased by the volume of the water shell. By determining the Vhyd of the LONs, one can calculate the degree

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• ]. The proposed formation of a bicyclic intermediate 18 resulting from a cycloaddition reaction would enhance the diastereoselectivity of the hydration step compared to an acyclic intermediate that would be formed in the step-wise mechanism to 18. The authors’ suggest the step-wise mechanism does play a

• role in reducing the diastereoselectivity of the reaction when the alkene is aryl- or alkyl-substituted. The hydration step can occur via pathway a or b to afford 17 (dr ca. 3:2). The N-acyliminium ions formed during an anodic oxidation of a silyl auxiliary can be coupled to a radical pathway using a

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• the active conformation of the enzyme molecule by destabilizing electrostatic interactions, and even strip off the essential water layer (water of hydration) leading to loss of the biocatalytic activity. In turn, more lipophilic organic solvents positively interact with the enzyme protein enhancing

Copper-promoted hydration and annulation of 2-fluorophenylacetylene derivatives: from alkynes to benzo[b]furans and benzo[b]thiophenes

• Yibiao Li,
• Liang Cheng,
• Xiaohang Liu,
• Bin Li and
• Ning Sun

Beilstein J. Org. Chem. 2014, 10, 2886–2891, doi:10.3762/bjoc.10.305

• Yibiao Li Liang Cheng Xiaohang Liu Bin Li Ning Sun School of Chemical & Environmental Engineering, Wuyi University, Jiangmen, Guangdong Province, 529090, China BASF Catalyst, 23800 Mercantile Road, Beachwood, Ohio 44124, USA 10.3762/bjoc.10.305 Abstract An efficient copper-promoted hydration

• reaction and its application in the synthesis of benzo[b]furan and benzo[b]thiophene derivatives is presented starting from readily available 2-fluorophenylacetylene derivatives. The key annulation step involves the hydration of the C–F bond of 2-fluorophenylacetylene derivatives followed by an

• product (Table 1, entry 1). The usage of CuCl and 1,10-phenanthroline (1,10-phen) as a ligand in CH3CN at 80 °C showed that 2a could be isolated in 35% yield (Table 1, entry 2). The screening of the various solvents revealed that the solvent played an important role in this hydration and annulation

Binding mode and free energy prediction of fisetin/β-cyclodextrin inclusion complexes

• Bodee Nutho,
• Wasinee Khuntawee,
• Chompoonut Rungnim,
• Piamsook Pongsawasdi,
• Peter Wolschann,
• Alfred Karpfen,
• Nawee Kungwan and
• Thanyada Rungrotmongkol

Beilstein J. Org. Chem. 2014, 10, 2789–2799, doi:10.3762/bjoc.10.296

• . From the atom–atom interaction RDF analysis, among all six oxygen atoms of fisetin in three complexes, no peak appeared within ~3 Å of the O1 atom, suggesting that this atom on the chromone ring has a relatively low water accessibility or very weak hydration interaction. Along the simulation this atom

• always seems to stay inside the hydrophobic cavity. Differentially, the other oxygen atoms show the first sharp peak centered at ~2.8 Å corresponding to a highly possible hydration and the first minimum at ~4 Å accounting for the time when a water molecule remains on the first solvation shell. On the

• -CD through the B-ring fitting at the narrow rim (complexes II–III), only the O7 atom on the A-ring was significantly higher solvated. The further discussion on the hydration of fisetin in complexation with β-CD is summarized as follows. Low hydration on the O3 atom (I–III: ~1.5, ~0.8 and ~0.6) was

Anomalous diffusion of Ibuprofen in cyclodextrin nanosponge hydrogels: an HRMAS NMR study

• Monica Ferro,
• Franca Castiglione,
• Carlo Punta,
• Lucio Melone,
• Walter Panzeri,
• Barbara Rossi,
• Francesco Trotta and
• Andrea Mele

Beilstein J. Org. Chem. 2014, 10, 2715–2723, doi:10.3762/bjoc.10.286

• , such as the chemical compositions of the nanosponge (e.g., CDNSPMA, CDNSEDTA are swellable, CDNSDPC are not) and the cross-linker to CD mole ratio n [17]. Recently, we demonstrated that the CDNS hydrogels undergo phase transitions by changing the hydration level h = m(H2O)/mCDNS by a complex interplay

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• , 2JC,P = 22.8 Hz, CO) ppm; 31P{1H} NMR (161.9 MHz, CDCl3, 25 °C) δ 40.5 (d, 1JP,Rh = 172 Hz) ppm; IR: 2086 (vs, CO), 2026 (vs, CO), 2004 (s, CO) cm−1; We do not provide microanalytical data for this compound because of strong hydration; MS (ESI–TOF): m/z (%): 1799.44 (70) [M – Cl]+, 1857.40 (100) [M

Pyrrolidine nucleotide analogs with a tunable conformation

• Lenka Poštová Slavětínská,
• Dominik Rejman and
• Radek Pohl

Beilstein J. Org. Chem. 2014, 10, 1967–1980, doi:10.3762/bjoc.10.205

• alternate between A, B and Z forms depending on the hydration and the type and concentration of metal ions, which is also reflected in the conformation of the sugar part. Finally, the conformation of ribose or its mimics also significantly predetermines the binding of a nucleoside, nucleotide or an analog

Synthesis of trifluoromethyl-substituted pyrazolo[4,3-c]pyridines – sequential versus multicomponent reaction approach

• Barbara Palka,
• Angela Di Capua,
• Maurizio Anzini,
• Gyté Vilkauskaité,
• Algirdas Šačkus and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2014, 10, 1759–1764, doi:10.3762/bjoc.10.183

• the corresponding ketones. The hydration of C–C triple bonds under the influence of various catalytic systems, including also Pd-based catalysts, is a well-known reaction [21][22]. It should be emphasized that NMR investigations with compounds 8a,c unambiguously revealed the methylene group adjacent

The search for new amphiphiles: synthesis of a modular, high-throughput library

• George C. Feast,
• Thomas Lepitre,
• Xavier Mulet,
• Charlotte E. Conn,
• Oliver E. Hutt,
• G. Paul Savage and
• Calum J. Drummond

Beilstein J. Org. Chem. 2014, 10, 1578–1588, doi:10.3762/bjoc.10.163

• layer of amphiphile prior to hydration of the material. The microscope slide was placed into a Linkam PE94 hot stage (Linkam Scientific Instruments Ltd.; Surrey, England) and a water drop added at the side of the cover slip to flood the sample and create a concentration gradient as water was absorbed

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

• as drugs in various therapies and as recognition units in diagnostics and sensing. However, the development of synthetic lectins poses a phenomenal challenge for supramolecular chemistry [37] because a carbohydrate receptor in order to be useful must not only compete with the strong hydration of

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

• Malamatenia D. Manouilidou,
• Yannis G. Lazarou,
• Irene M. Mavridis and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 774–783, doi:10.3762/bjoc.10.73

• both β-CD cavities (Figure 3d) are the least stable by PM3(COSMO) (in the presence of water), although highly favorable by PM3 (in the absence of solvent). This was attributed to insufficient hydration of the primary hydroxy groups due to steric crowding around the primary sides of the two β-CD tori

Integration of enabling methods for the automated flow preparation of piperazine-2-carboxamide

• Richard J. Ingham,
• Claudio Battilocchio,
• Joel M. Hawkins and
• Steven V. Ley

Beilstein J. Org. Chem. 2014, 10, 641–652, doi:10.3762/bjoc.10.56

• treatment of tuberculosis – and its reduced derivative piperazine-2-carboxamide. Keywords: automation; flow chemistry; hydration; hydrogenation; sustainable processing; Introduction Enabling synthesis technologies such as flow chemistry are becoming commonplace in modern laboratories (for recent reviews

• explored the possibility of developing a machine-automated synthesis of this compound which might later be extended to analogous structures. For the facile machine-assisted synthesis of 1 we devised and optimised the fully continuous sequential hydration of nitrile 3 to amide 2 and hydrogenation of

• pyrazine 2 to piperazine 1 (Figure 2b). Both of these steps involve flowing through heterogeneous catalysts, a metal oxide for the hydration of the nitrile and a supported precious metal for the hydrogenation of the heteroaromatic ring. Furthermore, both steps involve the addition of a volatile small

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• as essential tools in organic synthesis. Generally with the unique reactivity and mild reaction conditions, this type of transformation has found widespread applications in complex molecule synthesis [10][11]. Among those reactions, the gold-catalyzed hydration of alkynes is regarded as one of the

• signature reactions in the field (known as Teles hydration) [12]. This reaction usually utilized the combination of methanol and water, wherein methanol served as the nucleophile to attack the triple bond, forming the vinyl ether intermediate. This vinyl ether then collapsed to give a ketone as the final

• 1,3-diketones with unactivated alkynes at ambient temperature. Results and Discussion As indicated in Scheme 1, the main challenge for the intermolecular O-nucleophile addition to alkynes is the competitive hydration side reaction. Although, theoretically, strictly anhydrous conditions shall prevent

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• fluorine, its hydration and thus reduced nucleophilicity [21]. The importance of this developing research field is reflected by the various review articles which have been published dealing with transition metal mediated or catalyzed fluorination [22][23][24], difluoromethylation [24], and

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

• condensation of primary amines with o-diacylbenzene 19 (Scheme 2) [13]. After initial formation of 20, isomerization to 21 and 22 can occur through a sequential dehydration–hydration process. Dimerization of 21 and 22 generates 23, the substrate for a formal retro-Aldol reaction. Loss of formaldehyde gives 24

A concise enantioselective synthesis of the guaiane sesquiterpene (−)-oxyphyllol

• Martin Zahel and
• Peter Metz

Beilstein J. Org. Chem. 2013, 9, 2028–2032, doi:10.3762/bjoc.9.239

• the total synthesis of the anticancer guaiane (−)-englerin A. A regio- and diastereoselective Co(II)-catalyzed hydration of the olefin and a transannular epoxide opening were used as the key reactions. Keywords: asymmetric synthesis; hydration; natural products; terpenes; transannular epoxide opening

• completion of the synthesis of (−)-oxyphyllol (1) from 4. To our delight, a direct regio- and diastereoselective Co(II)-catalyzed hydration [12] of the olefin in 4 succeeded to give the required α-stereoisomer 3 in 58% isolated yield after chromatographic separation of the minor β-alcohol. Compared to the

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• stereoisomers of Ile are less hydrophobic than Aha. F6Leu is similar to Aha in hydrophobicity, while exhibiting a much larger volume. In a free energy perturbation study, the hydration energy of F6Leu was shown to be 1.1 kcal/mol higher than that of leucine [29]. This, together with our previous and new

• findings, suggests that there are two factors determining the overall hydrophobicity of fluorinated amino acids [26]. On one hand, substitutions of hydrogen by fluorine increase the solvent accessible surface area and thus lead to an increase in hydration energy. On the other hand, the C–F bond is more

A practical synthesis of long-chain iso-fatty acids (iso-C₁₂–C₁₉) and related natural products

• Mark B. Richardson and
• Spencer J. Williams

Beilstein J. Org. Chem. 2013, 9, 1807–1812, doi:10.3762/bjoc.9.210

• triethylsilane and BF3·Et2O [53], affording 11. Oxidative cleavage of 11 with KMnO4/Bu4NBr [54] afforded iso-C12 acid 1. Alternatively, anti-Markovnikov hydration of 11, using I2/NaBH4 then hydrogen peroxide [55], afforded the alcohol 12, and oxidation of 12 with KMnO4/Bu4NBr afforded iso-C13 acid 2

Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• formation of the hydration product 3 (Table 1, entries 2 and 3 versus entry 1). We found out that running the reaction at 70 °C instead of at room temperature completely prevented the byproduct formation. At this temperature good to quantitative yields of furans 2a were achieved in less than 30 min, and 5

• °C, no trace of furan 2a could be detected by 1H NMR analysis. Interestingly, decreasing the catalytic loading from 5 to 1 mol % still provided the furan in less than 1 h and in high yields (Table 1, entries 6 and 7 versus entry 5). However, hydration started to compete again at low loading, as

• hydration product, the reaction took 6 h to reach almost full conversion. Beside the expected furan 2d, its corresponding regioisomer 2d’ arising from 1,3-migration of the pivaloyl group is formed in this reaction and both products were obtained in a combined yield of 68% (Table 2, entry 4). We next varied

Aerobic radical multifunctionalization of alkenes using tert-butyl nitrite and water

• Daisuke Hirose and
• Tsuyoshi Taniguchi

Beilstein J. Org. Chem. 2013, 9, 1713–1717, doi:10.3762/bjoc.9.196

• hydroxy group arising from hydration of the olefin (entry 6). Functionalization reactions involving oxygenation of methylene C–H bonds of alkenes 11–13 also proceeded to afford secondary nitrate compounds 21–23, though no diastereoselectivity was observed (Table 2, entries 7–9). Unfortunately, no tertiary

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

• István E. Markó and
• Florian T. Schevenels

Beilstein J. Org. Chem. 2013, 9, 1319–1325, doi:10.3762/bjoc.9.148

• 13 was treated with aqueous hydrochloric acid, in the hope of generating the corresponding dihydrofuran carbaldehyde 33. Instead, the diol 34 was obtained in 52% yield as a 1:1 mixture of diastereoisomers. It thus transpires that protonation and hydration of the exo-methylene double bond of 13

• of two new dimers. Formation of (Z)-chloro-exo-methyleneketals. Mechanism of formation of (Z)-chloro-exo-methylenetetrahydrofurans. Stepwise formation of (Z)-chloro-exo-methylenetetrahydrofurans. Optimized protocols to form (Z)-chloro-exo-methylenetetrahydrofurans. Hydration of (Z)-chloro-exo

A computational study of base-catalyzed reactions of cyclic 1,2-diones: cyclobutane-1,2-dione

• Nargis Sultana and
• Walter M. F. Fabian

Beilstein J. Org. Chem. 2013, 9, 594–601, doi:10.3762/bjoc.9.64

• transition states, intermediates and products shown in Scheme 3, hydration by six water molecules is implied. Relative Gibbs free energies with respect to the separated reactants 1·(H2O)2 + [OH(H2O)4]– including bulk aqueous solvation energies (SMD solvation model [21]) obtained by various computational

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

• Cristina Tubaro,
• Marco Baron,
• Andrea Biffis and
• Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

• selectivity compared to the previously published complex AuCl(PPh3). Preliminary results on intramolecular hydroarylations using this catalytic system indicate, however, that alkyne hydration by traces of water may become a serious competing reaction. Keywords: alkyne; C–H functionalization; cyclisation

• VI moderate to very good conversions of the substrates were obtained, but the main reaction product was invariably the product of hydration of the triple bond 8, whereas the 6-endo-dig cyclisation product 7 was present in minor amounts. Gold(I) NHC complexes such as VI are known to be extremely

• efficient catalysts for alkyne hydration [61], hence it can be expected that alkyne hydration by traces of water may become a serious competitive reaction despite the low concentration of water in the reaction mixture. On the basis of the above, it can be hypothesised that in order to steer the reaction