CHEMISTRY OF HYDROGEN ISOCYANIDE .9. 3-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 pi-delocalization along the O-C-N-C-N(exo) chain which is also evident from severe low-field shifts of the C-2 and C-4 signals in the C-13-NMR spectra. The heterocycles are cleaved off the metal by oxidative decomposition with KMnO4/Fe(NO3)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.