Unusual carbamate-directed CH-activation at an annulated ferrocenophane framework

Abstract

The tetrahydroazepine-annulated [3]ferrocenophane carbamate (4) was synthesized by two different linear routes starting from the readily available α-dimethylamino[3]ferrocenophane-ortho-carbaldehyde rac-6. The carbamate directed lithiation of 4 resulted in a selective attack at a (Cp)C–H bond at the higher substituted “lower” [3]ferrocenophane Cp-ring to eventually yield the respective ester (18) after treatment with ClCO₂Me.