Metal-template-controlled stabilization of β-functionalized isocyanides

Dumke A. C., Pape T., Kösters J., Feldmann K. O., Schulte to Brinke C., Hahn F. E.

Abstract

Reaction of 2-azidoethyl isocyanide 1, 2-azidophenyl isocyanide 2, or 2-nitrophenyl isocyanide 3 with complexes [Mo(CO)3(dppe)(py)] [4] or [W(CO)3(dppe)(Nî-≡CCH3)] [5] yields the isocyanide complexes [Mo(CO)3(dppe)(Cî-≡NR)] ([6]: Cî-≡NR = 1; [12]: Cî-≡NR = 2; [13]: Cî-≡NR = 3) and [W(CO)3(dppe)(Cî-≡NR)] ([7]: Cî-≡NR = 1; [14]: Cî-≡NR = 2; [15]: Cî-≡NR = 3). Reduction of the nitro or azido groups attached to the isocyanide ligands by Zn/NH 4Cl (azidoethyl or azidophenyl isocyanides) or Raney-nickel/hydrazine hydrate (nitrophenyl isocyanide) yields exclusively the complexes bearing the 2-amino-functionalized isocyanides. The normally unstable 2-amino-functionalized isocyanides are stabilized by M→Cî-≡NR back-bonding, which deactivates the isocyanide carbon atom for an intramolecular nucleophilic attack by the primary amine. © 2012 American Chemical Society.