Unsaturated nitriles with organometallic

The experimental conditions for the syntheses starting from acid chlorides of hydroxamic acids and from nitrile oxides are somewhat different. In the former case the other component of the reaction is organometallic, usually an organomagnesium derivative of an acetylene or, less frequently, a sodium enolate of a /8-diketone. Nitrile oxides condense directly with unsaturated compounds. 

In this chapter, the scope, mechanism, and recent progress of zirconocene (Il)-mediated cyclization reactions are introduced. Zirconocene(II) is a very important reagent for organometallic chemistry, synthetic chemistry, and polymer chemistry. Zirconocene(II) is capable of coordinating with unsaturated compounds. Further reactions could lead to zirconocene(IV) species, zirconacycles, C-C bond formation, C-X bond formation, and synthesis of carbocycles and heterocycles. Zirconocene(lI)-mediated cyclization of bis(alkynyl)silane gives zirconacyclobu-tene-silacyclobutene complexes, which could react with alkyne, bis(alkynyl)silane, ketone, nitrile, and isocyanate and could be applied in the synthesis of various valuable products. 

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