In this Perspective, recent advances in the emerging field of transition metal-catalyzed C–H bond functionalization of ferrocene derivatives are summarized.

A convenient process for the direct functionalization of ferrocene that exploits the high electrophilic character of gold–vinyl carbenoids catalytically generated from vinyldiazo compounds and gold complexes is reported. This process takes place with complete regioselectivity (vinilogous reactivity). The synthesis of the corresponding ruthenocene analogues has also been achieved. Preliminary studies on the reactivity of these new organometallic compounds seem to suggest that the presence of the adjacent ferrocenyl group confers a specific reactivity on the functionalized carbon chain manifested in the easy dry state aerobic allylic oxidation.

A rhodium-catalyzed carbene transfer to alkynes is reported. Easily available enynones served as the carbene source replacing diazocompounds. The overall process involved a cyclization–cyclopropenation–ring enlargement sequence.

The reaction of N‐allenamides with alkenyl diazo compounds in the presence of gold catalysts provided methylidenecyclopentene derivatives resulting from a formal intermolecular [3+2] carbocyclization, a rare process in the gold chemistry of allenes. The participation of the CαCβ bond of the allenamide represents a very unusual regioselectivity in gold‐catalyzed cycloaddition reactions of this type of allenic scaffolds. A stepwise mechanism involving initial activation of the diazo component has been proposed. magnified image

The gold-catalyzed reaction of electronically unbiased allenes with alkenyldiazo compounds provided alkylidenecyclopentene derivatives resulting from a formal intermolecular (3+2) carbocyclization.