[3+2+1] cycloaddition involving alkynes, CO and bridging vinyliminium ligands in diiron complexes: a dinuclear version of the Dötz reaction?

Abstract

The vinyliminium complex [Fe2{mu-eta(1):eta(3)-C(SiMe3)=CHC=N(Me)2}(mu-CO)(CO)(Cp)2][SO3CF3] reacts with HC[triple bond]CR (R = CPh2OH), affording a mixture of the 2,4,6-trisubstituted oxo-eta(5)-cyclohexadienyl complex [Fe{eta(5)-C6H2O(NMe2)(SiMe3)(R)}(Cp)], the 2,6-disubstituted phenol C6H3R(NMe2)OH (R = CHPh2) and 1,2,4-trisubstituted ferrocene [1-NMe2-2-R-4-SiMe3-Fc]. The corresponding reaction with HC[triple bond]CR (R = CMe2OH) yields analogous products: [Fe{eta(5)-C6H2O(NMe2)(SiMe3)(R')}(Cp)] (R' = CMe=CH2), the phenol C6H3R'(NMe2)OH together with [1-NMe2-2-R-4-SiMe3-Fc].