Direct one step preparation and 13C-NMR spectroscopic characterization of a-ferrocenyl carbocations derived from ferrocene and carbonyl compounds in trifluoroacetic acid medium1a

Abstract

Reaction of aldehydes and ketones with ferrocene, in the presence of trifluoroacetic acid, afforded a series of stable long lived alpha-ferrocenylalkyl carbocations which were characterized by 13C-NMR spectroscopy. When this reaction was attempted using tetraphenylcyclopentadienone, quite unexpectedly the corresponding dihydro derivative 3 was isolated, in very good yield. Formation of this compound may require ferrocene acting as a reducing agent.

Keywords

• ferrocene
• alpha-ferrocenyl carbocations
• 13C-NMR of alpha-ferrocenylalkyl carbocations