benzofurans and 2-nitrobenzofuran

The application of dinuclear zinc catalysts in a dearomatization reaction has been developed. Catalytic asymmetric dearomatization [3+2] annulations of 2-nitrobenzofurans or 2-nitrobenzothiophenes with CF

Topics: Benzofurans; Catalysis; Isatin; Stereoisomerism; Zinc

The diastereo- and enantioselective dearomative formal [3 + 2] cycloaddition of 2-nitrobenzofurans and α-aryl-α-isocyanoacetate esters provides tricyclic compounds bearing the 3

Topics: Benzofurans; Catalysis; Cycloaddition Reaction; Esters; Stereoisomerism

In this manuscript, the first enantioselective dearomative Michael addition between α,β-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation has been described. The reaction proceeds

Topics: Aldehydes; Benzofurans; Catalysis; Stereoisomerism

A readily available chiral cyclohexanediamine-derived bifunctional tertiary amine-squaramide catalyst is more effective for the asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans and N-2,2,2-trifluoroethylisatin ketimines. A range of structurally diverse spiro-fused polyheterocyclic compounds containing oxindole, pyrrolidine, and hydrobenzofuran motifs were smoothly obtained in excellent results (up to 99% yield, >20:1 dr in all cases and up to 99% ee). This method features high efficiency, mild reaction conditions, exquisite asymmetric induction, wide functional group tolerance, great potential for scale-up synthesis, and attractive product diversification.

Topics: Benzofurans; Cycloaddition Reaction; Imines; Nitriles; Spiro Compounds; Stereoisomerism

Lignin is an abundant phenylpropanoid polymer produced by the oxidative polymerization of p-hydroxycinnamyl alcohols (monolignols). Lignification, i.e., deposition of lignin, is a defining feature of secondary cell wall formation in vascular plants, and provides an important mechanism for their disease resistance; however, many aspects of the cell wall lignification process remain unclear partly because of a lack of suitable imaging methods to monitor the process in vivo. In this study, a set of monolignol analogs γ-linked to fluorogenic aminocoumarin and nitrobenzofuran dyes were synthesized and tested as imaging probes to visualize the cell wall lignification process in Arabidopsis thaliana and Pinus radiata under various feeding regimens. In particular, we demonstrate that the fluorescence-tagged monolignol analogs can penetrate into live plant tissues and cells, and appear to be metabolically incorporated into lignifying cell walls in a highly specific manner. The localization of the fluorogenic lignins synthesized during the feeding period can be readily visualized by fluorescence microscopy and is distinguishable from the other wall components such as polysaccharides as well as the pre-existing lignin that was deposited earlier in development.

Topics: Arabidopsis; Benzofurans; Cell Wall; Coumaric Acids; Coumarins; Fluorescence; Lignin; Phenylpropionates; Pinus; Plant Cells; Propionates; Protoplasts; Seedlings

Various 3-alkyl-2-nitrobenzo[b]furans were synthesized from common intermediate 2-(2-nitroethyl)phenols via a hypervalent iodine-induced oxidative cyclization, with good to excellent yields. This facile route is able to efficiently functionalize 2-nitrobenzo[b]furans, which are difficult to obtain by classical methods.

Topics: Benzofurans; Cyclization; Iodine; Molecular Structure; Oxidation-Reduction

Generation of radical anions during NADPH reduction of four mutagenic and genotoxic alpha-nitroarenofurans was examined. ESR showed that free radicals were generated during reduction solely in the presence of light. Computer simulations of ESR spectra were in good agreement with the experimental ones.

Topics: Benzofurans; Computer Simulation; Electron Spin Resonance Spectroscopy; Free Radicals; Furans; Mutagens; NADP; Nitrofurans; Oxidation-Reduction; Photochemistry

Bisulfite catalyzes transamination of cytidine at the N4 position; the suitability of this reaction for attaching reporter groups to selected cytidine residues in RNA molecules has been investigated. Poly(C) is nearly quantitatively converted to the poly (N4 aminoethyl-C) derivative after 3 hrs at 42 degrees C with ethylene diamine (pK1 = 7.6) and bisulfite. This derivative reacts quantitatively with N-hydroxysuccinimide esters; the linkage of a fluorescent dye, nitrobenzofurazan, to cytidine by this reaction is demonstrated. To direct the bisulfite reaction to selected cytidines within a large RNA molecule, the RNA is hybridized to complementary DNA containing a deletion. Only the cytidines in the single strand RNA loop (corresponding to the DNA deletion) are reactive. Two cytidines in the middle of a 340 base RNA fragment from 16S ribosomal RNA have been modified by this technique.

Topics: Amines; Amino Acids; Antioxidants; Base Sequence; Benzofurans; Chemical Phenomena; Chemistry; Cloning, Molecular; Cytidine; Genetic Vectors; Indicators and Reagents; Nucleic Acid Conformation; Poly C; RNA; Sulfites

A group of 2-nitrobenzofurans possessing antibacterial and antiparasitic properties have now been shown to be potential radiosensitizers from investigations in simple aqueous solution by pulse radiolysis and from survival studies in yeast. The radical anions of several 2-nitrobenzofurans were formed by the rapid reaction of the parent molecules with hydrated electrons or with various pyrimidine electron adducts. Studies of equilibria between these radical anions, the parent nitrobenzofurans and the corresponding species derived from quinones with known one-electron reduction potentials, showed that the one-electron reduction potentials of all the furans under investigation lie between -285 and -309 mV. They are thus more electron affinic than the nitroimidazoles (misonidazole and metronidazole) currently under clinical evaluation. 5-Hydroxy- and 7-hydroxy-2-nitrobenzofuran were demonstrated to form weak complexes with DNA (binding constant 80 M-1) and strong complexes with HSA (binding constant 10(5)M-1). In the yeast Saccharomyces cerevisiae the nitrobenzofurans exert radiosensitizing effects on survival either similar to or higher than misonidazole.

Topics: Benzofurans; Cell Survival; DNA; Dose-Response Relationship, Radiation; Nitrofurans; Oxidation-Reduction; Radiation-Sensitizing Agents; Saccharomyces cerevisiae; Spectrophotometry; Structure-Activity Relationship