Organometallic compounds nitrile synthesis

Complexes of organotin with amidines have been found to be excellent catalysts for the preparation of polyurethane foams, which do not have the disadvantage of any amine odor and, in addition, delayed onset of the isocyanate-hydroxyl reaction An example of a mercapto-delayed organotin catalyst is 2,2,4,4-tetrakis(alkyl)- l,3,2,4-dithia-stannetane.55 Amine salts of amino acids, tertiary amino acids, and tertiary amino acid-nitrile compositions, have been found to be effective as delayed action catalysts for polyurethane synthesis. They are particularly effective when used in combination with an organometallic compound, such as an organotin. ... 

Organocerium reagents also show excellent reactivity toward nitriles and imines,205 and organocerium compounds were found to be the preferred organometallic reagent for addition to hydrazones in an enantioselective synthesis of amines.206... 

The aryl unit of these species shows carbanionic properties and consequently reacts with electrophiles. As a result, these organometallic reagents are of great value for the synthesis of a wide range of aromatic compounds. In particular, reaction with carbon electrophiles such as carbonyl compounds and nitriles results in the formation of a new carbon-carbon bond. 

The reaction of 1-boraadamantane (5) with aromatic nitriles also proceeds according to the organometallic synthesis scheme. As in the reaction with carbonyl compounds, the initially formed complexes (100) (Scheme 37) transform to dimers of 5-aryl-4-aza-3-bora-l,l-bihomoadamantane-4-enes (101) when heated higher than 200 °C <84JOM(260)25>. Compounds (101) are stable in the air and do not react with alcohols however, they can be cleaved with 8-hydroxyquinoline to give bicyclic compounds (102) <84jom(260)25>. 

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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