Chemie der Isoblausäure, 9. Dreikomponenten‐Cycloadditionen mit Cyanokomplexen

Abstract

Chemistry of Hydrogen Isocyanide, 9 [1] . — Three‐Component Cycloadditions with Cyano Complexes A novel and obviously general reaction of the coordinated cyano ligand in [M(CN)(CO) 5 ] — (M = Cr, W) is reported, viz. its high‐yield one‐step [2 + 1 + 2] cycloaddition with a great variety of isocyanides and ketones resulting in carbenoid metal complexes of five‐membered N,O heterocycles. The structure of the product 1a from [W(CN)(CO) 5 ] — , tert ‐butyl isocyanide, and diethyl ketone has been elucidated by X‐ray diffraction and found to contain a C‐bound non‐aromatic 4‐aminooxazoline with an unprecedented π‐delocalization along the magnified image exo chain which is also evident from severe low‐field shifts of the C‐2 and C‐4 signals in the 13 C‐NMR spectra. The heterocycles are cleaved off the metal by oxidative decomposition with KMnO 4 /Fe(NO 3 ) 3 to give the corresponding oxazolinones, e.g. 4 , with a high potential for biological activity. The general validity of this reactivity pattern for metal cyanides is further demonstrated by the successful incorporation of cyanoiron(II) and ‐cobalt(III) species in these three‐component cycloaddition reactions.