Heterogeneous electrochemical immunoassay of hippuric acid on the electrodeposited organic films.

By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on the electrode surface and then bonded Ni ion (positive charge) to induce immobilization of Fe-HA (negative charge) through the electrostatic interaction. The heterogeneous competitive immunoassay system relies on the interaction between immobilized Fe-HA antigen conjugate and free HA antigen to its antibody (anti-HA). The electric signal becomes weaker due to the hindered electron transfer reaction when a large-sized HA antibody is bound onto the Fe-HA. However, in the presence of HA, the electric signal increases because free HA competitively reacts with the HA antibody prior to actual reaction and thus prevents the HA antibody from interacting with Fe-HA at the electrode surface. This competition reaction enabled an electrochemical quantitative analysis of HA concentration with a detection limit of 0.5 µg mL(-1), and thus allowed us to develop a simple and rapid electrochemical immunosensor.

5-Substituted-2-furaldehydes: a synthetic protocol utilizing an organozinc route.

Facile synthetic routes for the preparation of a wide range of 5-substituted 2-furaldehydes have been revealed. They were accomplished through either Pd-catalyzed cross-coupling reaction of various aryl- and heteroarylzinc halides with 5-bromo-2-furaldehyde or utilization of a new organozinc reagent, 5-(1,3-dioxolan-2-yl)-2-furanylzinc bromide, which was easily prepared by the direct insertion of highly active zinc to 2-(5-bromofuran-2-yl-1,3-dioxolane. Of special note is the uniqueness of using a new organozinc reagent, representing a first example of the direct synthesis of the corresponding organozinc halide. The subsequent coupling reactions in various types of reaction conditions led to the formation of somewhat different furan derivatives. It is also of significance that all of the cross-coupling reactions were carried out under mild conditions.

Recent advance in heterocyclic organozinc and organomanganese compounds; direct synthetic routes and application in organic synthesis.

A practical synthetic route for the preparation of 2-pyridyl and 3-pyridyl derivatives has been accomplished by utilizing a simple coupling reaction of stable 2-pyridylzinc bromides and 3-pyridylzinc bromides. The organozincs used in this study were easily prepared via the direct insertion of active zinc into the corresponding bromopyridines. The subsequent coupling reactions with a variety of different electrophiles have afforded the corresponding coupling products. Using highly active manganese, a variety of Grignard-type organomanganese reagents have been obtained. The subsequent coupling reactions of the resulting organomanganese reagents with several electrophiles have also been accomplished under mild conditions.