CHEMISTRY OF HYDROGEN ISOCYANIDE .9. 3-CO MPONENT CYCLOADDITIONS WITHCYANO-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-ste p [2 + 1 + 2] cycloaddition with a great variety of isocyanides and ke tones resulting in carbenoid metal complexes of five-membered N,O hete rocycles. The structure of the product 1a from [W(CN)(CO)5]-, tert-but yl isocyanide, and diethyl ketone has been elucidated by X-ray diffrac tion 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 whi ch is also evident from severe low-field shifts of the C-2 and C-4 sig nals in the C-13-NMR spectra. The heterocycles are cleaved off the met al by oxidative decomposition with KMnO4/Fe(NO3)3 to give the correspo nding oxazolinones, e.g. 4, with a high potential for biological activ ity. The general validity of this reactivity pattern for metal cyanide s is further demonstrated by the successful incorporation of cyanoiron (II) and -cobalt(III) species in these three-component cycloaddition r eactions.