Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• products. An acetal-protected aldehyde could also be used providing enol phosphonate 3g in 52% yield. In this case, prolonged reaction times led to partial evolution of 3g into enol ether 4. This transformation may be explained by an acid-mediated elimination of ethanol likely caused by trace formation of

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• essentially zerovalent Ru nanoparticles promotes their catalytic ability towards several challenging reactions, such as CO oxidation [67][68] and hydrogen evolution [69]. Interestingly, pristine Ru(0) single crystals have been reported to perform poorly in these reactions when compared to the surface-oxidised

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• neurons; the regulation and functioning of these processes is still not satisfactorily understood [1][2][3][4]. The MT cytoskeleton is a finely tuned complex system that is highly conserved through evolution. Direct genetic modifications of tubulin that affect its functions risk causing a diversity of

Bacterial terpene biosynthesis: challenges and opportunities for pathway engineering

• Eric J. N. Helfrich,
• Geng-Min Lin,
• Christopher A. Voigt and
• Jon Clardy

Beilstein J. Org. Chem. 2019, 15, 2889–2906, doi:10.3762/bjoc.15.283

• during evolution. In contrast, the underlying mechanistic logic of terpene biosynthesis is based on repetitive electrophilic and nucleophilic functionalities in each oligomeric substrate, similar to nonmodular type II PKSs, coupled with conformational flexibility for enzyme-mediated juxtaposition of

• nature [39]. Therefore, evolution would likely favor organisms that can generate and retain chemical diversity at a low cost [38]. As a result, producing and “screening” a large number of specialized metabolites for potent TCs that can generate multiple products from simple building blocks is a huge

• reported [40]. In fact, different pathways have evolved in plants, fungi, and bacteria for this fascinating compound family in an extreme case of convergent evolution [41][42]. While the plant and fungal biosynthetic pathways are well studied [42], the bacterial pathway was studied to a lesser degree until

Emission and biosynthesis of volatile terpenoids from the plasmodial slime mold Physarum polycephalum

• Xinlu Chen,
• Tobias G. Köllner,
• Wangdan Xiong,
• Guo Wei and
• Feng Chen

Beilstein J. Org. Chem. 2019, 15, 2872–2880, doi:10.3762/bjoc.15.281

• relatedness to bacterial TPSs. The biological role of the volatile terpenoids produced by the plasmodia of P. polycephalum is discussed. Keywords: amoebae; evolution; terpene synthases; volatiles; Introduction Volatile organic compounds (VOCs) are used by many living organisms as chemical languages for

• ), suggesting two evolutionary origins of PpolyTPS genes. It is tempting to speculate that PpolyTPS2 and PpolyTPS3 may be derived from bacteria through horizontal gene transfer, which was recently demonstrated to have occurred from bacteria to fungi for the evolution of TPS genes [26]. It is also interesting to

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• gas evolution ceased. Solvents were removed using a rotary evaporator and the resulting intermediate was dissolved in dichloromethane (6 mL). meta-Chloroperbenzoic acid (75%, 2.301 g, 10 mmol) was dissolved in dichloromethane (10 mL), cooled in a dry ice–acetone bath, and the intermediate solution was

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

• Alessandro Iagatti,
• Baihao Shao,
• Alberto Credi,
• Barbara Ventura,
• Ivan Aprahamian and
• Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

• positive signal at <380 nm, where absorption of the E-isomer is expected, signals the occurrence of isomerization. This event is also associated to the aforementioned evolution in the visible region, clearly indicating a variation of the excited state electronic distribution. No further band-shape changes

• . The output of the global analysis retrieves the kinetic constants describing the evolution of the system and the associated spectral components, the so-called EADS (evolution associated difference spectra) which are shown in Figure 4b. As it can be noticed, the evolution occurring on the 0.6 ps

• an absorption band in the region where the E-isomer absorbs is indicative of the photoinduced Z/E isomerization event, which thus results to be an ultrafast process, as observed for other photoswitches – azobenzene in particular [32]. Upon this initial ultrafast evolution, the transient absorption

Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical complex

• Yoichi Kobayashi,
• Yukie Mamiya,
• Katsuya Mutoh,
• Hikaru Sotome,
• Masafumi Koga,
• Hiroshi Miyasaka and
• Jiro Abe

Beilstein J. Org. Chem. 2019, 15, 2369–2379, doi:10.3762/bjoc.15.229

• (355 nm). The difference may affect the ratio of isomer A and isomer B at the photostationary state (PSS) and initial relaxation kinetics at sub-picosecond time scales. Benzil was used for a reference sample. Figure 3a shows the time evolution of the transient absorption spectra of benzil in benzene

• (Equation 2) convolved with Gaussian pulse. The detail of the SVD analyses are shown in Supporting Information File 1. The evolution associated spectra (EAS) thus obtained indicate the resolved transient absorption spectra into each component of the kinetic models. Because the time window of our

• biradical generated instantaneously, respectively. It indicates that the biradical was also formed by the direct excitation of the PIC unit with 400 nm light. The spectral evolution from EAS1 (160 fs, grey line in Figure 3d) to EAS2 (1.4 ps, red line in Figure 3d) shows the C–N bond cleavage of the PIC unit

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• most positive compared to that of A2 and A1. The evolution of the iodine potential follows our experimental observation with iodoethynylazobenzene A3 being the strongest halogen bond donor and A1 being the weakest, within this series [48]. For potential, reversible photochemical control of

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• /EtOH 1:1 (v/v)). Photovoltaic parameters evolution with the increasing concentration of tBP in the electrolyte. Selected optical properties of compounds BOD-TTPA-alk and BOD-TTPA. Photovoltaic parameters of compounds BOD-TTPA-alk and BOD-TTPA (light source: AM1.5G at 100 mW·cm−2, electrolyte

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

• Manuel Pedrón,
• Laura Legnani,
• Maria-Assunta Chiacchio,
• Pierluigi Caramella,
• Tomás Tejero and
• Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

• , with P1, P2 and P3, respectively. A close inspection of the IRCs revealed a shoulder characteristic of a transient carbocation [23] which is more pronounced following the sequence R1 < R2 < R3. The preliminary analysis of the evolution of bonds along those IRCs further confirmed a high asynchronicity

• transient carbocation is supported by the disappearance of V(C1) and the trigonal planar geometry observed for C1 in the above indicated gap. The evolution of the electron population is in clear agreement with the development of a partial positive charge at C1 (+0.25 at point 100). The oxidation of

• tetrahydrothiophene (TS3). The IRC (black trace) and O–H (green trace), C–H (brown trace), and C–O (blue trace) distances are also given. The double red arrow indicates the delay between H transfer and C–O bond formation. ELF analysis for the oxidation of cyclopentane (R1). Left: evolution of the electron population

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• in organic synthesis [1][2]. Such species can undergo different reactions, driven either by their carbanionic or carbenic behavior [3][4], thus leading to various products. In contrast, the transmetalation of lithiated oxiranes and the evolution of the resulting species have been less explored

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• 8a or 9a. Оne of the stereoisomers can be formed directly during the reaction. To test this hypothesis, we decided to study the evolution of dr on the course of reaction by 1H NMR spectroscopy (Figure 3). The reaction of sulfone 5a with ω-nitrostyrene (6a) was chosen as the model reaction. Conversion

• the reaction was observed. Рharmacologically active sulfones. Structures of the ligands L1–L8. Evolution of the conversion of 5 and diastereomeric composition of the products of reaction of 5a with 6a in the presence of catalyst 7a (2 mol %) in chloroform-d. Time profile of epimerization and retro

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• DLS measurement result showed that the size of aggregates of 2 formed in H2O/MeCN (v/v = 10:1) was centered at 576.8 nm. It should be noted that the aggregates formed by 1 and 2 with specific shapes were obtained immediately after the preparation of solutions, without days’ evolution process [77

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• ][11]. Here, we report in detail the evolution of chemistry that provides an asymmetric entry to the tricarboxylate core of these natural products, with particular focus on tartrate alkylation methodology to establish the fully-substituted C-5 stereocentre (squalestatin numbering). Our studies in this

Phylogenomic analyses and distribution of terpene synthases among Streptomyces

• Lara Martín-Sánchez,
• Kumar Saurabh Singh,
• Mariana Avalos,
• Gilles P. van Wezel,
• Jeroen S. Dickschat and
• Paolina Garbeva

Beilstein J. Org. Chem. 2019, 15, 1181–1193, doi:10.3762/bjoc.15.115

• /bjoc.15.115 Abstract Terpene synthases are widely distributed among microorganisms and have been mainly studied in members of the genus Streptomyces. However, little is known about the distribution and evolution of the genes for terpene synthases. Here, we performed whole-genome based phylogenetic

• analysis of this genus is discussed. Keywords: biosynthesis; evolution; geosmin; Streptomyces; terpenes; Introduction Streptomyces are soil bacteria that belong to the order of actinomycetales and are a rich source of natural products with broad biotechnological interest. Species of this genus have a

• available in the NCBI database and compared the distribution of terpene synthase genes among them. Furthermore, we studied whether phylogenetic trees calculated based on the three most abundant terpene synthases in Streptomyces represent the evolution of the Streptomyces species based on the whole genome

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• using an encapsulated solvent purification system and were further dried over 4 Å molecular sieves. The evolution of reactions was monitored by analytical thin-layer chromatography using silica gel 60 F254 precoated plates. Flash chromatography was performed employing 230–400 mesh silica using the

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

• a decrease of the C–Cl vibration after the reaction. B: Low pressure nitrogen isotherm of NG-HCP demonstrating the textural properties. A: Evolution of pressure in the course of the reaction measured by the GTM system. The addition of 1 mL of Et2O is sufficient to drastically reduce the released

Precious metal-free molecular machines for solar thermal energy storage

• Meglena I. Kandinska,
• Snejana M. Kitova,
• Vladimira S. Videva,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• Stanislav B. Baluschev,
• Silvia E. Angelova and
• Aleksey A. Vasilev

Beilstein J. Org. Chem. 2019, 15, 1096–1106, doi:10.3762/bjoc.15.106

• constants of metal complexes were determined and are in good agreement with the literature data for reference dyes. The temporal evolution of trans-to-cis isomerization was observed in a real-time regime. The dyes demonstrated a low intrinsic fluorescence of their Ba2+ complexes and high yield of E/Z

• characteristic changes in the absorption spectra of dye 4b–Ba2+ complex under optical excitation with λ = 488 nm and intensity of 14 mW cm−2. The temporal evolution of the absorption at specific wavelength of λabs = 500 nm is demonstrated in Figure 3b: during the first time interval from t1 = 10 s up to t2 = 180

• × 10−4 M) with Ba2+ (cM = 1 M) on the irradiation time. b) Temporal absorption evolution, measured at λabs = 500 nm, upon irradiation. Experimental conditions: Excitation wavelength λexc = 488 nm; excitation intensity 14 mW cm−2, solvent, ACN; pulse duration t = 180 s. UV–vis absorption spectra of dye

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

• yellow to colorless during the addition of the borane dimethyl sulfide complex. Upon complete consumption of 2, distilled water (15 mL) was added to the reaction mixture slowly (dropwise at first) while vigorous gas evolution was observed. After completion of the gas evolution, sodium hydroxide (14 mL

• for 2 h. The reaction mixture went from light yellow to colorless during the addition of the borane dimethyl sulfide complex. Upon complete consumption of the starting material, distilled water (0.66 mL) was added to the reaction mixture slowly (dropwise at first) while vigorous gas evolution was

• observed. After completion of the gas evolution, sodium hydroxide (131 µL, 0.131 mmol, 1 M) and hydrogen peroxide (33%, 13 µL, 0.131 mmol) were added, and the reaction mixture left for 2 h. Upon completion of the reaction, 1 M hydrochloric acid was added to the reaction mixture until the pH was

Mechanistic investigations on multiproduct β-himachalene synthase from Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 1008–1019, doi:10.3762/bjoc.15.99

• compound mixture need to be precise [1]. However, in some cases, compound mixtures have proven to be superior to the properties of the single compounds by evolution. Examples demonstrating this principle can be found in pheromone chemistry, like the bark beetle aggregation blend of ipsdienol, ipsenol and

• a single enzyme that can produce a beneficial mixture, the advantage for the producing organism is even higher. Therefore, selectivity is not in every case the highest goal for evolution. An enzyme class, which is highly prone to a regulation of product selectivity for the production of either one

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

• thermal half-lives (THL) of the cis-isomers of compounds 5a, 5b, 12a, 16a–d, 23, and 28 was accomplished by monitoring the increase in absorbance which corresponds to the evolution of the trans-isomer after irradiation and exposure to dark. In contrast to the heterocyclic compounds 5a, 5b, 12a, and 16a–d

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• by a spectrophotometer Thermo Scientific Evolution 201 using a wavelength range from 200 to 900 nm. Infrared spectra of the polymer were registered applying an FTIR spectrometer Simeks FT-801 in the range from 500 to 4000 cm−1. A silicon plate with a diameter of 8 mm was applied to support the

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• cm−1; HR-ESIMS (+νe mode) m/z (%): [M + H]+ calcd for C48H55N6O7, 827.4132; found, 827.4135 (100), Δm = 0.3 ppm; anal. calcd for C48H54N6O7.CH2Cl2: C, 64.54; H, 6.19; N, 9.22; found: C, 64.81; H, 6.32; N, 8.85. Timeline for the structure evolution of crown-capped DBTAAs (created on the basis of

Back to the future: Why we need enzymology to build a synthetic metabolism of the future

• Tobias J. Erb

Beilstein J. Org. Chem. 2019, 15, 551–557, doi:10.3762/bjoc.15.49

• produced should not be dictated by the serendipity and constraints of evolution, but be accessible through rational design. However, this requires a fundamental understanding of those principles that are necessary for designing, realizing and operating multi-reaction sequences and metabolic networks de

• can these new enzyme reactions be identified or established? One option is the de novo-design of enzymes assisted by computational methods, which have been developed over the last couple of years. When combined with experimental evolution and elaborate screening methods, these efforts have allowed to

• methods that succeeded in creating active sites of remarkable promiscuous activities in the scaffold of existing enzymes [42]. Such computationally-created “catalytically diverse active sites” could be further developed towards a new activity through directed evolution. Without any question, screening