Progress on Detection of Metals Ions by Functional Nucleic Acids Biosensor

Functional nucleic acids are natural or artificial nucleic acid sequences with specific functions and special structures. A part of metal ions are essential trace elements of human health, but excessive metal ions will be harmful to human health. The functional nucleic acids are widely used for detection of metal ions because of its advantages such as easy modification, low price, high stability and strong specificity. This paper detailed the interaction between functional nucleic acids and metal ions, mainly including cutting type, link type, metal ion-mediated base pairing, click chemistry type, conformational change type, and other types. The biosensors based on the combination of functional nucleic acid with different signal output were then introduced. Finally, the research significance and existing problems of functional nucleic acid for metal ion detection were discussed. The future development trends and applications of functional nucleic acid biosensor were prospected.     

Palladium-Catalyzed Asymmetric [4+3] Cyclization of Trimethylenemethane: Regio-, Diastereo-, and Enantioselective Construction of Benzofuro[3,2-b]azepine Skeletons

The palladium-catalyzed asymmetric [4+3] cyclization of trimethylenemethane donors with benzofuran-derived azadienes furnishes chiral benzofuro[3,2-b]azepine frameworks in high yields (up to 98 %) with exclusive regioselectivities and excellent stereoselectivities (up to >20:1 d.r., >99 % ee). This catalytic asymmetric [4+3] cyclization of Pd-trimethylenemethane can enrich the arsenal of Pd-TMM reactions in organic synthesis. In addition, this strategy provides an alternative approach to chiral azepines by a transition-metal-catalyzed asymmetric [4+3] cyclization.