Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

SO₂F₂-mediated transformation of 2'-hydroxyacetophenones to benzo-oxetes

• Revathi Lekkala,
• Ravindar Lekkala,
• Balakrishna Moku,
• K. P. Rakesh and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 976–980, doi:10.3762/bjoc.15.95

• by the base (K2CO3) generating phenoxide A, which subsequently reacts with SO2F2 to give intermediate B with concomitant release of a fluoride anion. The proton of the acetyl group adjacent to the carbonyl moiety in intermediate B is deprotonated by the base (K2CO3) to generate enolated intermediate

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• release of carbon dioxide from the molecule. We performed theoretical computations to better understand the reaction mechanism shown in Scheme 4 (Figure 3). For this purpose, we employed density functional theory (DFT) calculations and performed geometric optimizations using the B3LYP functional [19][20

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• other oxygen species. The TGA (Figure 1b) is another method to confirm the number of attached oxygen species and substituents. The first step up to 180 °C fits the release of secondary and tertiary bond water. The measurement shows that 12 H2O molecules are bound to the fullerene. The second step up to

• around 800 °C can be assigned to the release of the different oxygen species, which also explains the little steps which correspond to different oxygen types. In addition to the oxygen species attached to the fullerene core, the methoxy moieties of the substituent are also released. The average number of

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• 1,2-di(pyridin-4-yl)ethylene and 4,6-dichlororesorcinol in the transition state (Figure 24). Finally the cyclobutane derivative 43 was observed after the release of catalyst for the next cycle. In 2012, again the MacGillivray group reported an improved version of the above mentioned [2 + 2

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• character, 2,2,6,6-tetramethyl-1-(1-(2-(4-nitrophenyl)benzofuran-6-yl)ethoxy)piperidine (2a) and its regioisomer 2b, were designed and synthesized. The one-photon (OP) (365 ± 10 nm) and TP (710–760 nm) triggered release (i.e., uncaging) of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical under air

• atmosphere were discovered. The quantum yields for the release of the TEMPO radical were 2.5% (2a) and 0.8% (2b) in benzene at ≈1% conversion of 2, and 13.1% (2a) and 12.8% (2b) in DMSO at ≈1% conversion of 2. The TP uncaging efficiencies were determined to be 1.1 GM at 740 nm for 2a and 0.22 GM at 730 nm

• photochemical release of nitroxides should be achieved in the presence of O2. Thus, the triplet sensitized method may not be useful for physiological studies. The application of alkoxyamines as theranostic agents [37][38][39][40] has been proposed and reported by Brémond and co-workers [41][42]. Near-infrared

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• release [21][22]. Besides targeting of 5-HT3Rs for the treatment of psychiatric disorders, they are object to counteract postoperative nausea and chemo-/radiotherapy provoked emesis [26][27][28][29]. In the early 1990s, the first potent and selective 5-HT3 receptor antagonist ondansetron was initially

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

• the reaction time extended, an enol ether formation takes place during the acetalization. We followed the acetal formations by 1H NMR spectroscopy, and it was shown that the formed acetal product starts to degrade in a slower consecutive step, which leads to release of the enol ether derivative, e.g

Design and synthesis of multivalent α-1,2-trimannose-linked bioerodible microparticles for applications in immune response studies of Leishmania major infection

• Chelsea L. Rintelmann,
• Tara Grinnage-Pulley,
• Kathleen Ross,
• Daniel E. K. Kabotso,
• Angela Toepp,
• Anne Cowell,
• Christine Petersen,
• Balaji Narasimhan and
• Nicola Pohl

Beilstein J. Org. Chem. 2019, 15, 623–632, doi:10.3762/bjoc.15.58

• studies evaluating altered particle degradation rate(s) and encapsulation of trimannose within the particle could also be performed to provide sustained release of the trimannose. Conclusion Herein we described our newly designed pathogen-associated bioerodible microparticle 2 for investigation into the

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• intermediate (Scheme 2, intermediates II and IV) [16]. The catalytic cycle involves an initial [2 + 2] cycloaddition between a metal carbene I and an olefin, followed by a retro [2 + 2] cycloaddition, leading to the release of a “scrambled” olefin (e.g., ethylene in Scheme 2) and the metal carbene species III

• fluorescent in the presence of ethylene, thus leading to the release of 101 from the Ru-catalyst (Scheme 22). Live cell experiments with Chlamydomonas reinhardtii suggest that 20 µM of probe 102 in PBS buffer are sufficient to turn fluorescence on in cells flushed with exogenous ethylene or ethylene gas

LCST phase behavior of benzo-21-crown-7 with different alkyl chains

• Yan Deng,
• Xing Li,
• Qiao Zhang,
• Zheng Luo,
• Chengyou Han and
• Shengyi Dong

Beilstein J. Org. Chem. 2019, 15, 437–444, doi:10.3762/bjoc.15.38

• interactions can realize controlled release and product separation in complex supramolecular systems [35]. More options of small molecules with LCST properties not only give rise to more flexibility for LCST systems and thermo-responsive materials, but would be a great advantage for functionalization. In our

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• +, NMN and NAD+ are readily hydrolyzed to Nam, with their rapid decomposition particularly promoted by heat and basic aqueous solutions (pH ≥ 8). Under non-buffered conditions, the hydrolysis of the glycosidic bond leads to the release of Nam, which possesses a pKa at 3.35 [47]. The release of Nam

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• can significantly improve such properties of the polymer as thermal and oxidative resistance, surface properties, improvement of mechanical properties as well as reduced flammability, heat release and viscosity during processing [29]. Synthesis, properties and applications of POSS-containing materials

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• -alloThr18 was first eliminated by the base (OH− ion), followed by the release of Val22-COO− ion and the production of dhThr. This process follows an E2-type elimination mechanism (see a Newman projection), thus leading to compound A, which has an E-double bond for dhThr instead of a Z-double bond. Compound

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• Core 2.93 GHz, 16 GB RAM, 2 146 GB HDD), 40 × Compute Nodes: (HP BL460C G6 - 2 Quad Core 2.93 GHz, 16 GB RAM, 2 146 GB HDD, ProLiant BL2 x 220c G5, HP BL460C G1), 1 × 3 TB HP EVA 4400 SAN and 1x HP BL460C G6 Storage Server, Operating system on compute nodes: Scientific Linux SL release 5.3, Cluster

• operating system: Rocks 5.2 - Scientific Linux SL release 5.3. Structures of Grubbs 1 (1) and 2 (2) precatalysts. Structures of Grubbs 1-type (3) and 2-type (4) pyridinyl-alcoholato precatalysts. Structures of Grubbs 2-type (5) pyridinyl-alcoholato precatalysts. Structures of pyridinyl-substituted Grubbs 2

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• the AP and IP forms are present in the resting enzyme [54] and decarboxylation, rather than formation of the first intermediate, was found to be rate limiting [60]. On the other hand, product release was the slowest step for ZmPDC and ScPDC [61], so clearly not all ThDP-dependent enzymes behave in the

Unexpected loss of stereoselectivity in glycosylation reactions during the synthesis of chondroitin sulfate oligosaccharides

• Teresa Mena-Barragán,
• José L. de Paz and
• Pedro M. Nieto

Beilstein J. Org. Chem. 2019, 15, 137–144, doi:10.3762/bjoc.15.14

• glycosyl trichloroacetimidate [34] 1 and the corresponding glycosyl acceptor, such as 2. Subsequent delevulination would release the 4-OH group at the non-reducing end for next glycosylation. The C8F17 tail at position 6 of the galactosamine reducing end unit would allow us to purify the reaction

Synthesis of a tubugi-1-toxin conjugate by a modulizable disulfide linker system with a neuropeptide Y analogue showing selectivity for hY1R-overexpressing tumor cells

• Rainer Kufka,
• Robert Rennert,
• Goran N. Kaluđerović,
• Lutz Weber,
• Wolfgang Richter and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2019, 15, 96–105, doi:10.3762/bjoc.15.11

• transport form which after recognition at the target site is cleaved to release an active form. It should be be sufficiently stable in plasma to survive delivery, and ideally should improve solubility and cell entry. After all, only very few toxins are known that are suitable for PDCs, and the design and

New standards for collecting and fitting steady state kinetic data

• Kenneth A. Johnson

Beilstein J. Org. Chem. 2019, 15, 16–29, doi:10.3762/bjoc.15.2

• that substrate binding was at equilibrium, and was later expanded by Briggs and Haldane [3] who used the steady state approximation to include the rates of substrate and product release in defining Km according to a minimal model. A century later, we know the structures of enzymes and can accurately

• provides a lower limit for the second order rate constant for substrate binding. Similarly, kcat provides a lower limit for each first order rate constant following substrate binding through product release. On the other hand, the Michaelis constant cannot be interpreted unambiguously in the absence of

• = 100 μM−1s−1) then make the chemistry step irreversible and product release at least 100-fold faster than k2 so that the rate of chemistry defines kcat. This represents the standard (often erroneous) interpretation of kcat and Km. However, because we are only using this approximation to fit steady

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• ruthenium complexes by physisorption rather than chemisorption, an unexpected molecular rearrangement of their ligand sphere, determining a cis orientation of the neutral ligands, was observed (113 and 114, Figure 20). The same unusual cis configuration was displayed by complex 115 (Figure 20) upon release

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• : these processes are usually slow, expensive by requiring high temperature and high energy and release solvent (VOC). As an alternative of thermal polymerizations, polymerization upon light irradiation offers a good alternative. In both cases, polymerization occurs by the action of an initiating system

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

• Rudolf Knorr and
• Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

• Scheme 1). For this purpose, A1M1 should be demetalated through work-up to give, for instance, the alcohol A1H; the subsequent deprotonation of A1H by an M2-containing base BM2 must be complete before the generated alkoxide A1M2 begins to release C–M2 that would otherwise be protonated by any unconsumed

• , metal cation assistance was not necessary for the rapid carbanion release from the α-silyl compound 24 in the presence of Bu4N+F− in catalytic amounts. (ii) Most of the above alkoxide fission reactions were conducted in the presence of an electrophile for trapping the released nucleofugal carbanion

• ). Preparation and cleavage of the adduct 18 of fluoren-9-one (15). Proton transfer from dicyclopropyl ketone (19) to 2Li. Metal-free release of the carbanion unit in 25 and its seizure by t-BuCH=O (→ 7); Bu = n-butyl. Supporting Information Supporting Information File 336: Ion-pair intermediate through

Reactions of 3-(p-substituted-phenyl)-5-chloromethyl-1,2,4-oxadiazoles with KCN leading to acetonitriles and alkanes via a non-reductive decyanation pathway

• Akın Sağırlı and
• Yaşar Dürüst

Beilstein J. Org. Chem. 2018, 14, 3011–3017, doi:10.3762/bjoc.14.280

• − anions, cyanoimine salt intermediate A forms by addition to a nitrile. Then, a possible cyanogen release would occur to form intermediate B. The imine–enamine tautomerization of B by the effect of in situ-generated HCN results in the desired decyanated product 4 (Scheme 2). Conclusion In summary, we

• nitrile group into an alkane by using KCN–HCN associates through a possible release of cyanogen which is not detected or isolated. This synthetic protocol seems to be applicable for further decyanation processes containing a 1,2,4-oxadiazole moiety. Synthesis of mono- or dialkylated acetonitriles

Volatiles from the hypoxylaceous fungi Hypoxylon griseobrunneum and Hypoxylon macrocarpum

• Jan Rinkel,
• Alexander Babczyk,
• Tao Wang,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 2974–2990, doi:10.3762/bjoc.14.277

• that was supported by a feeding experiment with (methyl-2H3)methionine. Keywords: constitutional isomerism; gas chromatography; mass spectrometry; natural products; volatiles; Introduction Fungi release a large number of different volatiles that belong to all kinds of natural product classes [1

The activity of indenylidene derivatives in olefin metathesis catalysts

• Maria Voccia,
• Steven P. Nolan,
• Luigi Cavallo and
• Albert Poater

Beilstein J. Org. Chem. 2018, 14, 2956–2963, doi:10.3762/bjoc.14.275

• the phosphine release, and the relative stability of the corresponding metallacycle over classical ylidene ligands. Mayer bond orders and steric maps provide structural reasons for these effects, whereas NICS aromaticity and conceptual DFT confirm that the electronic parameters do not play a

• . Overall, among the catalysts with substituted indenylidene catalysts, the one bearing a SIMes NHC ligand and methyl groups in the indenylidene moiety is the most promising, in agreement with the experimental hypothesis that the release of the indenylidene ligand is more facile in such a case. The

• difficult to activate since the MBO of the Ru–P is larger by 0.045, 0.042, 0.060 and 0.051, respectively. Overall, despite the unfavourable effect on the activation of the precatalytic species I, the substituted indenylidenes do not affect at all the 14e species II once generated through phosphine release