Chlorodimethylaluminum-promoted nucleophilic addition of lithium pentamethylcyclopentadienide to aliphatic aldehydes and DDQ-mediated carbon–carbon bond cleavage of the adducts providing the parent aldehydes
摘要:
Treatment of aliphatic aldehyde with lithium pentamethylcyclopentadienide in the presence of chlorodimethylaluminum provided the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentacliene by the action of a catalytic amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). (c) 2005 Elsevier Ltd. All rights reserved.
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
dienide (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
五甲基环戊二烯化锂(C 5 Me 5 Li,Cp * Li)与芳族醛反应以优异的产率提供相应的甲醇。甲醇在暴露于酸中或加热后会返回为母体醛和五甲基环戊二烯。氯二甲基铝对于实现Cp * Li向脂肪族醛的亲核加成反应至关重要。衍生自脂族醛的甲醇在催化量的2,3-二氯-5,6-二氰基苯并醌(DDQ)的作用下返回母体醛和五甲基环戊二烯。Cp *基团的可逆加成/消除可表示对醛的保护。还公开了碳-碳键裂解的机理细节。