Copper-Catalyzed Alkene Aminoazidation as a Rapid Entry to 1,2‑Diamines and Installation of an Azide Reporter onto Azahetereocycles

A copper-catalyzed aminoazidation of unactivated alkenes is achieved for the synthesis of versatile unsymmetrical 1,2-diamine derivatives. This transformation offers an effective approach to installing an amide and an azide from two diffenent amino precursors onto both terminal and internal alkenes, with remarkable regio- and stereoselectivity. Mechanistic studies show that this diamination reaction proceeds via a nucleophilic amino cyclization followed by an intermolecular C–N bond formation using electrophilic azidoiodinane. This pathway differs from previous azidoiodinane-initiated alkene functionalization, suggesting new reactivity of azidoiodinane. Furthermore, this aminoazidation reaction provides an efficient strategy to introduce azide, one of the most useful chemical reporters, onto a broad range of bioactive azaheterocycles, offering new opportunities in bioorthogonal chemistry and biological studies. Rapid syntheses of 5-HT_2C agonist, (−)-enduracididine and azido-cholesterol derivatives demonstrate broad applications of this method in organic synthesis, medicinal chemistry, and chemical biology

Cationic Pd(II)-Catalyzed Highly Enantioselective Arylative Cyclization of Alkyne-Tethered Enals or Enones Initiated by Carbopalladation of Alkynes with Arylboronic Acids

Cationic Pd(II)-catalyzed enantioselective arylative cyclization of alkyne-tethered enals or enones initiated by carbopalladation of alkynes was developed without the necessity of a redox system

Dual Nickel- and Photoredox-Catalyzed Asymmetric Reductive Cross-Coupling To Access Chiral Secondary Benzylic Alcohols

Transition-metal-catalyzed asymmetric cross-coupling represents a powerful strategy for C–C bond formation and the synthesis of enantiomerically pure molecules. Here, we report a dual nickel/photoredox-catalyzed enantioselective reductive cross-coupling of aryl halides with α-bromobenzoates, readily generated from aliphatic aldehydes, to provide diverse chiral secondary benzylic alcohols that are important motifs in bioactive natural products and pharmaceuticals. This dual catalytic system features mild conditions, good functional group tolerance, broad substrate scope, excellent enantiocontrol, and avoidance of stoichiometric metal reductants, presenting great potential for late-stage functionalization of complex molecules

Cationic Pd(II)-Catalyzed Reductive Cyclization of Alkyne-Tethered Ketones or Aldehydes Using Ethanol as Hydrogen Source

A cationic Pd(II)-catalyzed reductive cyclization of alkyne-tethered ketones or aldehydes using ethanol as hydrogen source under mild conditions was developed. The reaction is an environmentally benign synthetic method and proceeds efficiently to give useful <i>N</i>-heterocycles or carbocycles bearing an exocyclic double bond and a hydroxyl group in high yield

Cationic Pd(II)-Catalyzed Highly Enantioselective Arylative Cyclization of Alkyne-Tethered Enals or Enones Initiated by Carbopalladation of Alkynes with Arylboronic Acids

Cationic Pd(II)-catalyzed enantioselective arylative cyclization of alkyne-tethered enals or enones initiated by carbopalladation of alkynes was developed without the necessity of a redox system

Copper-Catalyzed Amino Lactonization and Amino Oxygenation of Alkenes Using <i>O</i>‑Benzoylhydroxylamines

A copper-catalyzed amino lactonization of unsaturated carboxylic acids has been achieved as well as the analogous intermolecular three-component amino oxygenation of olefins. The transformation features mild conditions and a remarkably broad substrate scope, offering a novel and efficient approach to construct a wide range of amino lactones as well as 1,2-amino alcohol derivatives. Mechanistic studies suggest that the reaction proceeds via a distinctive <i>O</i>-benzoylhydroxylamine-promoted electrophilic amination of alkenes

Copper-Catalyzed Amino Lactonization and Amino Oxygenation of Alkenes Using <i>O</i>‑Benzoylhydroxylamines

A copper-catalyzed amino lactonization of unsaturated carboxylic acids has been achieved as well as the analogous intermolecular three-component amino oxygenation of olefins. The transformation features mild conditions and a remarkably broad substrate scope, offering a novel and efficient approach to construct a wide range of amino lactones as well as 1,2-amino alcohol derivatives. Mechanistic studies suggest that the reaction proceeds via a distinctive <i>O</i>-benzoylhydroxylamine-promoted electrophilic amination of alkenes

Defective UiO-66-NH₂ (Zr) for Simultaneous Adsorption of Phosphate and Pb²⁺ for Hydrogen Peroxide Purification

Removal of hetero ions from the hydrogen peroxide solution is a crucial step in purifying electronic-grade H2O2. Conventional adsorption materials are challenged to meet the need for the simultaneous adsorption of both anions and cations in solvents. UiO-66 (Zr) modified by acetic acid and amino group for simultaneous adsorption of phosphate and Pb2+ in H2O2 purification was fabricated in this work. The as-prepared defective UiO-66-NH2 (Zr) demonstrated a significant increase in specific surface area and porosity, along with more exposed sites for phosphate and Pb2+ adsorption. The adsorption capacity of De-UiO-66-NH2 for phosphate and Pb2+ in H2O2 solution was 52.28 mg g–1 and 35.4 mg g–1, which is 1.19 times and 1.88 times that of unmodified UiO-66 (Zr), respectively. The trace simultaneous adsorption with both 100 ppb phosphate and Pb2+ showed removal rates of 94.0% and 88.7%, respectively, confirming the practicality of MOF materials in the purification of electronic chemicals. This work highlights the potential of Zr-based MOFs as anionic and cationic simultaneous adsorbents for highly efficient purification of electronic-grade solvents

Frequencies and chromosomal location of genetic and DNA methylation changes detected by AFLP and MSAP.

<p>(A) Frequencies of genetic changes detected by AFLP analysis and revealed by various patterns of variant bands in the three F1 hybrids. (B) Frequencies of DNA methylation changes detected by MSAP analysis and revealed by various patterns of cytosine methylation in the three F1 hybrids. In both (A) and (B), the variant bands in the hybrids were determined by comparison with the parental mix. (C) Chromosomal location of the variant AFLP and MSAP bands. The three colors (red, green and purple) denote origins of variant bands from Hybrid 1, Hybrid 2 and Hybrid 3, respectively.</p

Immediate Genetic and Epigenetic Changes in F1 Hybrids Parented by Species with Divergent Genomes in the Rice Genus (<i>Oryza</i>)

<div><p>Background</p><p>Inter-specific hybridization occurs frequently in higher plants, and represents a driving force of evolution and speciation. Inter-specific hybridization often induces genetic and epigenetic instabilities in the resultant homoploid hybrids or allopolyploids, a phenomenon known as genome shock. Although genetic and epigenetic consequences of hybridizations between rice subspecies (e.g., japonica and indica) and closely related species sharing the same AA genome have been extensively investigated, those of inter-specific hybridizations between more remote species with different genomes in the rice genus, Oryza, remain largely unknown.</p><p>Methodology/Principal Findings</p><p>We investigated the immediate chromosomal and molecular genetic/epigenetic instability of three triploid F1 hybrids produced by inter-specific crossing between species with divergent genomes of <i>Oryza</i> by genomic in situ hybridization (GISH) and molecular marker analysis. Transcriptional and transpositional activity of several transposable elements (TEs) and methylation stability of their flanking regions were also assessed. We made the following principle findings: (<i>i</i>) all three triploid hybrids are stable in both chromosome number and gross structure; (<i>ii</i>) stochastic changes in both DNA sequence and methylation occurred in individual plants of all three triploid hybrids, but in general methylation changes occurred at lower frequencies than genetic changes; (<i>iii</i>) alteration in DNA methylation occurred to a greater extent in genomic loci flanking potentially active TEs than in randomly sampled loci; (<i>iv</i>) transcriptional activation of several TEs commonly occurred in all three hybrids but transpositional events were detected in a genetic context-dependent manner.</p><p>Conclusions/Significance</p><p>Artificially constructed inter-specific hybrids of remotely related species with divergent genomes in genus <i>Oryza</i> are chromosomally stable but show immediate and highly stochastic genetic and epigenetic instabilities at the molecular level. These novel hybrids might provide a rich resource of genetic and epigenetic diversities for potential utilization in rice genetic improvements.</p></div