EFFET DE SOLVANT SUR SUPPORT SOLIDE: REGIOSELECTIVITE DE L'ALKYLATION DES ENOLATES DE L'ACETYLACETATE D'ETHYLE PAR LE SULFATE D'ETHYLE EN PRESENCE DE "HMPT SOLIDE"

Article abstract of DOI:10.1016/S0040-4020(01)92093-9

The reaction of Li, Na, K enolates of ethylaceto acetate with diethylsulfate in THF at room temperature gives 60-70percent O-alkylation when performed in presence of one molar equivalent of solid HMPA.Without HMPA, in the same conditions, Li enolate does not react, Na enolate only gives C-alkylation while K enolate leads to 90percent C-alkylation, the reactions being quite slower in the two latter cases.The effects of one molar equivalent of solid and liquid HMPA are compared: for the K enolate the reaction is faster and the degree of O-alkylation higher with solid HMPA; practically no difference is seen for Na enolate, while the reverse is observed with the Li enolate.The cooperative effect of the polymer should thus only work for a sufficiently large cation, as the Li enolate is fixed on the solid HMPA in a larger amount than the K enolate.The study of this reaction is proposed to test the efficiency of other "solid solvents" interacting strongly with cations.