Applications of Isocyanide Complexes

Isocyanide complexes have found numerous applications in organic synthesis and catalysis. Isocyanides undergo polymerization in the presence of many transition metal complexes, for instance, metal carbonyls, metallocenes, cyclopentadienyl carbonyls, nickel(II), palladium(II), and cobalt(II) complexes. Exceptionally high activity is exhibited by nickel and cobalt carbonyls. The resulting polymers are Schiff bases  

Metallic copper and some copper compounds catalyze additions of alcohols to isocyanides. In this way esters of alkylimineformic acid (formimidates) may conveniently be prepared. 

Isocyanides that possess an acidic hydrogen atom in the a position may be added to the C = C bond of the a, jS-unsaturated cyanides, ketones, and esters to give heterocyclic compounds [equations (12.60) and (12.61)].  

In the presence of cyclooctadiene cobalt complexes as well as compounds such as [Ni(COD)2], [Ni(CNR)4], [RhCl(PPh3)3], etc., isocyanides are oxidized to isocyanates. 

The nickel(O) complex Ni4(CNBu07 catalyzes reduction of acetylenes to olefins, isocyanides and cyanides to amines, as well as cyclotrimerization of acetylene and cyclodimerization of butadiene. Reduction of isocyanides is also catalyzed by other clusters (Chapter 13). Isocyanide copper compounds catalyze addition of CH2CIY (Y = COOR, COR, CN) to olefins leading to the formation of cyclopropane derivatives 

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