Dedicated to the 70th anniversary of the discovery of ferroceneFerrocenyl triflates are known to undergo anionic thia-Fries rearrangements at low temperature in high yields. In order to expand the scope of this reaction, ferrocenyl sulfonates and sulfonylferrocenes were prepared and their reactivity investigated. Treatment of ferrocenyl fluorosulfonate with lithium 2,2,6,6-tetramethylpiperidide gave rise to a new anionic thia-Fries rearrangement at ferrocene. The formation of a rare oxathiine was observed with ferrocenyl (pentafluorophenyl) sulfonate as a result of an ortho lithiation and a subsequent intramolecular nucleophilic aromatic substitution. In contrast to fluorinated ferrocenyl sulfonates, fluorosulfonylferrocene as well as (trifluoromethylsulfonyl)ferrocene underwent ortho lithiation under comparable reaction conditions.

The Cover Feature shows the reactions of ferrocene fluorosulfonate vs. ferrocenyl fluorosulfone with non‐nucleophilic lithium amide bases leading to an anionic thia‐Fries rearrangement in the first case and to an ortho lithiation in the second case, highlighting the difference in reactivity of two similar ferrocene derivatives. More information can be found in the Full Paper by H. Butenschön and co‐workers.