Pentamethylcyclopentadienide in organic synthesis: nucleophilic addition of lithium pentamethylcyclopentadienide to aromatic aldehydes and carbon–carbon bond cleavage of the adducts affording the parent aldehydes

Treatment of aromatic aldehyde with lithium pentamethylcyclopentadienide provided the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene upon exposure to an acid or due to heating. The combination of the two reactions can represent a protection of aromatic aldehyde.