Isocyanides as One-Carbon Unit

Insertion of isocyanides into zirconacyclopentanes and zirconacyclopentenes affords the corresponding zirconocene q -imine complexes. Cyclopentylamine derivatives could be prepared by trapping of the insertion intermediates using alkenes, alkynes, and carbonyl compounds [50]. For example, insertion of phenylisocyanide into bicyclic zirconacyclopentenes affords iminoacyl complexes that rearrange to give a, )0-unsaturated zirconocene q -imine complexes. These complexes react with alkenes or alkynes to give cyclopententylamines (Eq.48) [51]. 

Isocyanides can also insert into metallacyclopentadienes [52]. Majoral and coworkers reported insertion of isocyanides into indenylzirconacyclopentadi-enes and proved the formation of rj -imine zirconocene complex, which is in-tramolecularly stabilized by a phosphino group. Elimination of the metal fragment Cp2Zr give the corresponding jS-phosphino imine derivatives or the unexpected jS-iminophosphine by hydrolysis with HCl (Eq. 49) [53]. 

If a sterically hindered isocyanide was used, only iminocyclopentadienes were formed in the presence of CuCl or NiCl2(PPh3)2 (Eq. 50) [54]. 

---