Photoredox-catalyzed trifluoromethylation of 2H-indazoles using TT-CF3+OTf- in ionic liquids.

A protocol for metal and oxidant free photoredox catalyzed trifluoromethylation of 2H-indazoles was developed by using Eosin Y as the photocatalyst and recoverable ionic liquids as the solvents. A series of trifluoromethylated products were obtained in moderate to good yields in this protocol under mild conditions. The reaction proceeded via a free-radical mechanism with a broad substrate range, excellent regioselectivity, and good functional group tolerance. Furthermore, the utility of this protocol was demonstrated by the synthesis of a highly selective ligand for estrogen receptor beta (ERß) and the drug granisetron. The protocol provides a mild and environmentally friendly solution for trifluoromethylation reaction.

The good, the bad, and the red: implicit color-valence associations across cultures.

Cultural differences-as well as similarities-have been found in explicit color-emotion associations between Chinese and Western populations. However, implicit associations in a cross-cultural context remain an understudied topic, despite their sensitivity to more implicit knowledge. Moreover, they can be used to study color systems-that is, emotional associations with one color in the context of an opposed one. Therefore, we tested the influence of two different color oppositions on affective stimulus categorization: red versus green and red versus white, in two experiments. In Experiment 1, stimuli comprised positive and negative words, and participants from the West (Austria/Germany), and the East (Mainland China, Macau) were tested in their native languages. The Western group showed a significantly stronger color-valence interaction effect than the Mainland Chinese (but not the Macanese) group for red-green but not for red-white opposition. To explore color-valence interaction effects independently of word stimulus differences between participant groups, we used affective silhouettes instead of words in Experiment 2. Again, the Western group showed a significantly stronger color-valence interaction than the Chinese group in red-green opposition, while effects in red-white opposition did not differ between cultural groups. Our findings complement those from explicit association research in an unexpected manner, where explicit measures showed similarities between cultures (associations for red and green), our results revealed differences and where explicit measures showed differences (associations with white), our results showed similarities, underlining the value of applying comprehensive measures in cross-cultural research on cross-modal associations.

A visible-light-induced cascade reaction of etherification/C-C cyclization: efficient synthesis of dibenzo[b,d]oxepin-7(6H)-ones.

A visible-light-induced palladium-catalyzed cascade reaction was developed by etherification/C-C coupling cyclization of α-bromoacetophenones with phenols. A series of dibenzo[b,d]oxepin-7(6H)-one derivatives were efficiently synthesized by using this method in good yields. Furthermore, this method was applied to the synthesis of protosappanin A. The protocol has advantages such as simple reaction conditions, wide range of substrates and high reaction efficiency.

Visible-Light-Induced Decarboxylation Coupling/Intramolecular Cyclization: A One-Pot Synthesis for 4-Aryl-2-quinolinone Derivatives.

A visible-light-induced decarboxylation coupling/intramolecular cyclization is reported. The one-pot synthesis system provides mild, efficient, and atom economical access to the synthesis of 4-aryl-2-quinolinone derivatives. It is notable that the necessary oxidant in the traditional decarboxylation coupling is replaced by the visible-light irradiation in this paper. In addition, the HBV inhibitor is synthesized by the one-pot synthesis system in an atom economical manner.

Synthesis of 8-azaprotosappanin A derivatives via intramolecular palladium-catalyzed ortho C-H activation/C-C cyclization and their antibacterial activity.

A novel synthetic protocol for the construction of eight-membered heterocycles by intramolecular palladium-catalyzed ortho C-H activation/C-C cyclization was proposed. With protosappanin A as the lead compound, 25 derivatives of 8-azaprotosappanin A were prepared in good yields by this protocol. Besides, a plausible reaction mechanism of the intramolecular cyclization was proposed. This strategy could be widely used in the synthesis of some natural products and drugs with large heterocycles due to the fast reaction rate and the mild conditions. In vitro antimicrobial activities of the synthesized compounds were assessed against the strains of Gram-positive bacteria and linezolid and ciprofloxacin were selected as the standard drugs. Some of the synthesized compounds were found to have excellent antibacterial activities.

Associations between intronic non-B DNA structures and exon skipping.

Non-B DNA structures are abundant in the genome and are often associated with critical biological processes, including gene regulation, chromosome rearrangement and genome stabilization. In particular, G-quadruplex (G4) may affect alternative splicing based on its ability to impede the activity of RNA polymerase II. However, the specific role of non-B DNA structures in splicing regulation still awaits investigation. Here, we provide a genome-wide and cross-species investigation of the associations between five non-B DNA structures and exon skipping. Our results indicate a statistically significant correlation of each examined non-B DNA structures with exon skipping in both human and mouse. We further show that the contributions of non-B DNA structures to exon skipping are influenced by the occurring region. These correlations and contributions are also significantly different in human and mouse. Finally, we detailed the effects of G4 by showing that occurring on the template strand and the length of G-run, which is highly related to the stability of a G4 structure, are significantly correlated with exon skipping activity. We thus show that, in addition to the well-known effects of RNA and protein structure, the relative positional arrangement of intronic non-B DNA structures may also impact exon skipping.

Crystal structure and highly luminescent properties studies of bis-ß-diketonate lanthanide complexes.

A new bis(ß-diketonate), 1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)phenyl (BTP), which contains a trifluorinated alkyl group, has been prepared for the synthesis of two series of dinuclear lanthanide complexes with the general formula Ln2(BTP)3L2 [Ln(3+) = Eu(3+), L = DME(1), bpy(2), and phen(3); Ln(3+) = Sm(3+), L = DME(4), bpy(5), and phen(6); DME = ethylene glycol dimethyl ether, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline]. The crystal structure of the free ligand has been determined and shows a twisted arrangement of the two binding sites around the 1,3-phenylene spacer. X-ray crystallographic analysis reveals that complexes 1, 2, 4, and 5 are triple-stranded dinuclear structures formed by three bis-bidentate ligands with two lanthanide ions. The room-temperature photoluminescence (PL) spectra of complexes 1-6 show that this bis-ß-diketonate can effectively sensitize rare earths (Sm(3+) and Eu(3+)) and produce characteristic emissions of the corresponding Eu(3+) and Sm(3+) ions. In addition, two bidentate nitrogen ancillary ligands, 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), have been employed to enhance the luminescence quantum yields and lifetimes of both series of Eu(3+) and Sm(3+) complexes.

N-Cyano-2,2'-biphenyldicarboimide as a Cyanation Reagent for Co(III)-Catalyzed C-H Cyanation of Indoles in Ionic Liquids.

A mild strategy for Co(III)-catalyzed C(sp2)-H cyanation of indoles was developed by using NCBLD as an electrophilic cyanation reagent and 1-butyl-3-acetylimidazole ditrifluoromethylsulfonimide ([BAIM]NTf2) as an environmentally friendly and recyclable solvent, and a series of 2-cyano products were obtained at room temperature. Adopting this strategy, the unnatural nucleotide fragment precursor of Remdesivir, which was a drug for COVID-19, was synthesized through cyano transformation, further proving the practicability of this cyanation method.

N-Trifluoromethyl Succinimide as a New Reagent for Direct C-H Trifluoromethylation of Free Anilines.

N-trifluoromethylsuccinimide (NTFS) as a new trifluoromethylation reagent was designed and prepared via Ag-CF3 , and applied to the direct trifluoromethylation of free aniline, and a series of trifluoromethyl products were obtained with good yields. The practicability of the protocol was verified by a gram-level experiment and the synthesis of the antiasthmatic drug Mabuterol. In addition, a possible radical mechanism was proposed and verified by related experiments. The protocol provided a new solution for C-H trifluoromethylation of free anilines.

2,9,10-Trimeth-oxy-dibenzo[b,d]oxepin-7(6H)-one.

The title compound, C(17)H(16)O(5), was prepared through a cyclization reaction of 2-(3',4',5-trimeth-oxy-biphenyl-2-yl-oxy)acetyl chloride. The two benzene rings form a dihedral angle of 34.55 (5)°. The crystal structure does not feature any hydrogen bonds.

3a,11b-Dihy-droxy-3a,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline-2(3H)-thione.

The title compound, C(13)H(10)N(4)O(2)S, was prepared through a cyclization reaction of 1,10-phenanthroline-5,6-dione and thio-urea. The dihedral angle between the pyridine rings is 8.22 (2)°. In the crystal, mol-ecules are connected by N-H⋯O, O-H⋯N, N-H⋯S and O-H⋯S hydrogen bonds, forming a three-dimensional network.

3,4-Dimeth-oxy-4'-nitro-1,1'-biphen-yl.

The title compound, C(14)H(13)NO(4), was prepared through a palladium-catalysed Suzuki-Miyaura coupling reaction. The asymmetric unit comprises two mol-ecules related by pseudo-inversion symmetry. The dihedral angles between the benzene rings in the two mol-ecules are 44.30 (6) and 48.50 (6)° while those between the benzene ring and the nitro group are 6.54 (13) and 5.73 (10)°. The crystal packing is defined only by Van der Waals inter-actions.

3',4'-Dimeth-oxy-biphenyl-4-carbonitrile.

The title compound, C(15)H(13)NO(2), was prepared through a palladium-catalysed Suzuki-Miyaura coupling reaction. The dihedral angle between the biphenyl rings is 40.96 (6)°. The meth-oxy groups are twisted slightly out of the plane of the benzene ring [C-C-C-C torsion angles = -3.61 (18) and 12.6 (2)°]. The packing of the molecules is stabilized by van der Waals inter-actions.

Visible-Light-Induced Acylative Coupling of Benzoic Acid Derivatives with Alkenes to Dihydrochalcones.

A strategy was developed for the visible-light-induced photocatalytic synthesis of dihydrochalcone via the deoxygenation and coupling of benzoic acid derivatives with alkenes using diphenyl sulfide as the O-transfer reagent. Under mild photoredox conditions, a series of dihydrochalcone derivatives were produced in moderate to good yields. A mechanism for the visible-light-induced free-radical coupling was proposed on the basis of the control experiments. The protocol provides a new strategy the generation of acyl radicals from carboxylic acids and the synthesis of dihydrochalcones.

Visible light-induced deoxygenation/cyclization of salicylic acid derivatives and aryl acetylene for the synthesis of flavonoids.

A visible-light-induced photocatalytic strategy for the synthesis of flavonoids has been developed through the deoxygenative/cyclization reaction of salicylic acid derivatives with aryl acetylene using diphenyl sulfide as an O-transfer reagent. Based on the controlled experiments, the mechanism of visible-light-induced free radical coupling cyclization was proposed. The protocol obtained 51 flavonoids in good yields and has been successfully applied to the synthesis of some natural flavones.

Evidence of association between nucleosome occupancy and the evolution of transcription factor binding sites in yeast.

BACKGROUND: Divergence of transcription factor binding sites is considered to be an important source of regulatory evolution. The associations between transcription factor binding sites and phenotypic diversity have been investigated in many model organisms. However, the understanding of other factors that contribute to it is still limited. Recent studies have elucidated the effect of chromatin structure on molecular evolution of genomic DNA. Though the profound impact of nucleosome positions on gene regulation has been reported, their influence on transcriptional evolution is still less explored. With the availability of genome-wide nucleosome map in yeast species, it is thus desirable to investigate their impact on transcription factor binding site evolution. Here, we present a comprehensive analysis of the role of nucleosome positioning in the evolution of transcription factor binding sites. RESULTS: We compared the transcription factor binding site frequency in nucleosome occupied regions and nucleosome depleted regions in promoters of old (orthologs among Saccharomycetaceae) and young (Saccharomyces specific) genes; and in duplicate gene pairs. We demonstrated that nucleosome occupied regions accommodate greater binding site variations than nucleosome depleted regions in young genes and in duplicate genes. This finding was confirmed by measuring the difference in evolutionary rates of binding sites in sensu stricto yeasts at nucleosome occupied regions and nucleosome depleted regions. The binding sites at nucleosome occupied regions exhibited a consistently higher evolution rate than those at nucleosome depleted regions, corroborating the difference in the selection constraints at the two regions. Finally, through site-directed mutagenesis experiment, we found that binding site gain or loss events at nucleosome depleted regions may cause more expression differences than those in nucleosome occupied regions. CONCLUSIONS: Our study indicates the existence of different selection constraint on binding sites at nucleosome occupied regions than at the nucleosome depleted regions. We found that the binding sites have a different rate of evolution at nucleosome occupied and depleted regions. Finally, using transcription factor binding site-directed mutagenesis experiment, we confirmed the difference in the impact of binding site changes on expression at these regions. Thus, our work demonstrates the importance of composite analysis of chromatin and transcriptional evolution.

ProteDNA: a sequence-based predictor of sequence-specific DNA-binding residues in transcription factors.

This article presents the design of a sequence-based predictor named ProteDNA for identifying the sequence-specific binding residues in a transcription factor (TF). Concerning protein-DNA interactions, there are two types of binding mechanisms involved, namely sequence-specific binding and nonspecific binding. Sequence-specific bindings occur between protein sidechains and nucleotide bases and correspond to sequence-specific recognition of genes. Therefore, sequence-specific bindings are essential for correct gene regulation. In this respect, ProteDNA is distinctive since it has been designed to identify sequence-specific binding residues. In order to accommodate users with different application needs, ProteDNA has been designed to operate under two modes, namely, the high-precision mode and the balanced mode. According to the experiments reported in this article, under the high-precision mode, ProteDNA has been able to deliver precision of 82.3%, specificity of 99.3%, sensitivity of 49.8% and accuracy of 96.5%. Meanwhile, under the balanced mode, ProteDNA has been able to deliver precision of 60.8%, specificity of 97.6%, sensitivity of 60.7% and accuracy of 95.4%. ProteDNA is available at the following websites: http://protedna.csbb.ntu.edu.tw/, http://protedna.csie.ntu.edu.tw/, http://bio222.esoe.ntu.edu.tw/ProteDNA/.

4-Meth-oxy-2-nitro-4'-(trifluoro-meth-yl)biphen-yl.

The title compound, C(14)H(10)F(3)NO(3), was prepared by a palladium-catalysed Suzuki-Miyaura coupling reaction. The dihedral angle between the nitro group and its parent benzene ring is 66.85 (19)° while the dihedral angle between the two benzene rings is 49.98 (9)°. The CF(3) group is disordered over two sets of sites with occupancies of 0.457 (8) and 0.543 (8).

Ni-Catalyzed C-H Cyanation of (Hetero)arenes with 2-Cyanoisothiazolidine 1,1-Dioxide as a Cyanation Reagent.

A nickel-catalyzed C-H cyanation reaction of arenes has been developed using 2-cyanoisothiazolidine 1,1-dioxide as an electrophilic cyanation reagent. Many different directing groups can be used in this cyanation to obtain a series of cyanation products with good yields. Adopting this strategy to introduce a cyano group, natural alkaloid menisporphine was successfully synthesized through cyano group conversion that further proved the practicality of this cyanation method.

Ethyl N-[3-(N,N-dimethyl-carbamo-yl)pyridin-2-ylsulfon-yl]carbamate.

In the mol-ecular structure of the title compound, C(11)H(15)N(3)O(5)S, the amide group is nearly perpendicular to the pyridine ring, making a dihedral angle of 86.30 (13)°. The terminal ethyl group is disordered over two sites of equal occupancy. Inter-molecular N-H⋯O hydrogen bonding is present in the crystal structure.