Search results for " ring"
showing 10 items of 478 documents
Molecular evolution of tomato black ring virus and de novo generation of a new type of defective RNAs during long‐term passaging in different hosts
2020
Tomato black ring virus (TBRV) is a worldwide-distributed RNA virus infecting a wide range of different host plants, including crop species, trees, shrubs, and weeds. Here, we investigated the molecular evolution of TBRV and its adaptability to different plant species. The TBRV-Pi isolate was used to generate five independent evolution lineages serially passaged in either quinoa, tobacco, or tomato plants. After 15 passages, the genetic variability present in all the lineages was characterized for the movement (MP) and coat (CP) coding cistrons. We addressed two main questions: to what extent does the amount of genetic variability in the TBRV genome depend on the host species, and are there…
Synthesis of Lamellarin D Trimethyl Ether and Lamellarin H via 6π-Electrocyclization.
2015
An electrocyclic ring closure of a 2-azapentadienyl anion generated in situ from a chalcone and glycine ester is the key step of an efficient synthesis of the pyrrole core of the lamellarin alkaloids. A recently developed scalable one-pot procedure provides multigram quantities of a 3,5-diaryl-4-iodopyrrole-2-carboxylate intermediate which is transformed in four further high-yielding operations including a one-pot Pomeranz–Fritsch alkylation/cyclization and an Ullmann-type lactone ring closure into the pentacyclic lamellarin skeleton.
On the use of multi-parameter free energy relationships: the rearrangement of (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into (2-aryl-5…
2010
Abstract By using a multi-parameter approach (a combination of Hammett/Ingold-Yukawa-Tsuno/Fujita-Nishioka free energy relationships) the mononuclear rearrangements of heterocycles (MRH) rates for five new ortho-substituted and ten new di-, tri-, or tetra-substituted (Z)-arylhydrazones of 5-amino-3-benzoyl-1,2,4-oxadiazole into the relevant (2-aryl-5-phenyl-2H-1,2,3-triazol-4-yl)ureas (in dioxane/water and in a large range of pS+ values) have been related to the electronic and proximity effects exerted by the present substituents, also considering previous results on some mono meta- and para-substituted (Z)-arylhydrazones. In every case, excellent correlation coefficients have been calculat…
Crystal structure and Hirshfeld surface analysis of (E)-3-(benzylideneamino)-5-phenylthiazolidin-2-iminium bromide
2020
The central thiazolidine ring of the title salt, C16H16N3S+center dot Br-, adopts an envelope conformation, with the C atom bearing the phenyl ring as the flap atom. In the crystal, the cations and anions are linked by N-H center dot center dot center dot Br hydrogen bonds, forming chains parallel to the b-axis direction. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H center dot center dot center dot H (46.4%), C center dot center dot center dot H/H center dot center dot center dot C (18.6%) and H center dot center dot center dot Br/Br center dot center dot center dot H (17.5%) interactions.
Multiscale variation in drought controlled historical forest fire activity in the boreal forests of eastern Fennoscandia
2017
Forest fires are a key disturbance in boreal forests, and characteristics of fire regimes are among the most important factors explaining the variation in forest structure and species composition. The occurrence of fire is connected with climate, but earlier, mostly local-scale studies in the northern European boreal forests have provided little insight into fire-climate relationship before the modern fire suppression period. Here, we compiled annually resolved fire history, temperature, and precipitation reconstructions from eastern Fennoscandia from the mid-16th century to the end of the 19th century, a period of strong human influence on fires. We used synchrony of fires over the network…
Long-term decrease in Asian monsoon rainfall and abrupt climate change events over the past 6,700 years
2021
Significance The variability of the Asian summer monsoon (ASM) is important for the functioning of ecological and societal systems at regional to continental scales, but the long-term evolution and interannual variability of this system is not well understood. Here, we present a stable isotope–based reconstruction of ASM variability covering 4680 BCE to 2011 CE. Superimposed on a gradual drying trend, a rapid drop in mean annual precipitation (>40%) toward persistently drier conditions occurred in ∼1675 BCE. This megadrought caused regional forest deterioration and enhanced aeolian activity affecting Chinese ecosystems. We argue that this abrupt aridification starting ∼2000 BCE triggered wa…
Crystal structure of 1-(2-fluorobenzoyl)-2,7-dimethoxynaphthalene
2014
The asymmetric unit of the compound contains two independent conformers. Each conformer is stacked along the a axis to form columns through van der Waals interactions only.
Crystal structure and Hirshfeld surface analysis of 1-(2,4-dichlorobenzyl)-5-methyl-N-(thiophene-2-sulfonyl)-1H-pyrazole-3-carboxamide
2018
In the title compound, C16H13Cl2N3O3S2, the thiophene ring is disordered in a 0.762 (3):0.238 (3) ratio by an approximate 180° rotation of the ring around the S—C bond linking the ring to the sulfonyl unit. The dichlorobenzene group is also disordered over two sets of sites with the same occupancy ratio. The molecular conformation is stabilized by intramolecular C—H...Cl and C—H...N hydrogen bonds, forming rings with graph-set notation S(5). In the crystal, pairs of molecules are linked by N—H...O and C—H...O hydrogen bonds, forming inversion dimers with graph-set notation R 2 2(8) and R 1 2(11), which are connected by C—H...O hydrogen-bonding interactions into ribbons parallel to (100). Th…
Crystal structure and Hirshfeld surface analysis of (E)-1-[2,2-dichloro-1-(4-nitrophenyl)ethenyl]-2-(4-fluorophenyl)diazene
2019
The dihedral angle between the 4-fluorophenyl ring and the nitro-substituted benzene ring of the title compound is 63.29 (8)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds into chains parallel to the c axis. The crystal packing is further stabilized by C—Cl⋯π, C—F⋯π and N—O⋯π interactions
Crystal structure and Hirshfeld surface analysis of 2-[(1,3-benzoxazol-2-yl)sulfanyl]-N-(2-methoxyphenyl)acetamide
2019
Akkurt, Mehmet/0000-0003-2421-0929; Saylam, Merve/0000-0002-7602-4565