- Deprotonation des allylbenzenes chrometricarbonyle en milieu basique. Influence du systeme basique et du groupement chrometricarbonyle sur la regioselectivite de l'addition des derives carbonyles et sur la nature des produits isoles
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Allylbenzene chromiumtricarbonyl complexes are deprotonated under several basic conditions: tBuOK-THF, NaH-DMF and phase transfer catalysis.The regioselectivity of the addition of carbonyl compounds on the complexed allylic anions is influenced by the nature of the cations M+.With M+ = K+, Na+, N+ (nBu)4 the reaction of aromatic aldehydes is under thermodynamic control; only the most stable alcohols, dienes or ketones are isolated.With M+ = K+, ketones are formed by an in situ Oppenauer-Woodward oxidation.With M+ = Li+ the reaction is in great part under kinetic control.Benzaldehyde gives rise to a mixture of α and γ alcohols.With acetophenone and diethyl ketone the reaction is regiospecific.Only the linear alcohols are obtained.This result, different from that obtained in non-complexed series under similar conditions, is the consequence of the steric strain of the complexed benzenic nucleus.
- Senechal-Tocquer, M.-C.,Senechal, D.,Bihan, J.-Y. Le,Gentric, D.,Caro, B.
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p. 185 - 205
(2007/10/02)
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