Cobalt isocyanide derivatives

Reaction of FeCo2(CO)9S with a series of phosphines (31, 133) and isocyanides (126) yielded mono-, di-, and trisubstituted derivatives, Eqs. (77) and (78). 57Fe-Mossbauer spectra of the phosphine-substituted derivatives indicated that substitution at cobalt occurs prior to substitution at iron (31). Unfortunately, no crystallographic evidence has been obtained for any of these derivatives, and the precise stereochemistry has not been resolved, even with the aid of l3C-NMR spectra (9). The problem is compounded with the isocyanide ligands since several isomers of the trisubstituted derivatives are formed. 

The catalyst-free 5-1-1-cycloaddition reaction between C, A(-cyclic A -acyl azome-thine imines (134) with isocyanides (135) formed imin-l,3,4-oxadiazin-6-one derivatives (136) in high to excellent yields (99%) under mild conditions (Scheme 42). The cobalt-mediated / -pentadienyl (137)/alkyne (138) 5-1-2-cycloaddition reaction yielded /, -cycloheptadienyl complexes (139) under kinetic control. The initial cycloadducts are isomerized to the final >/ -cycloheptadienyl complexes (140) (Scheme 43). The Ru(I)-catalysed intra- and intermolecular 5 4- 2-cycloaddition reactions of 3-acyloxy-l,4-enynes and alkynes produced adducts with highly functionalized seven-membered rings. The reaction sequence includes a 1,2-acyloxy migration. The catalyst-free 5 4- 2-cycloaddition reaction of 2-vinylaziridines with sulfonyl isocyanates in CH2CI2 yielded seven-membered cyclic ureas in high yields (up to 90%). ... 

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