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 com
Pentamethylcyclopentadienide in organic synthesis: Nucleophilic addition of lithium pentamethylcyclopentadienide to carbonyl compounds and carbon-carbon bond cleavage of the adducts yielding the parent carbonyl compounds
Lithium pentamethylcyclopentadienide (C5Me5Li, Cp*Li) reacted with aromatic aldehyde to provide the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene upon exposure to acid or due to heating. Chlorodimethylaluminum is essential as an additive to attain the nucleophilic addition of Cp*Li to aliphatic aldehyde. The carbinol derived from aliphatic aldehyde returns to the parent aldehyde and pentamethylcyclopentadiene by the action of a catalytic amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). The reversible addition/elimination of the Cp* group can represent a protection of aldehyde. Mechanistic details of the carbon-carbon bond cleavage are also disclosed.