Alkylation of Carbonyl Compounds in Water: Formation of CC and CO Bonds in the Presence of Surfactants

The formation of CC and CO bonds by the reaction of enolate intermediates with electrophilic substrates commonly requires strong bases, aprotic solvents and very low temperatures. A way of performing the same reactions with sodium hydroxide at moderate temperatures in aqueous surfactant solutions is presented. Different halides, ketones and surfactants (cationic, zwitterionic and anionic) have been used. The results obtained show that the amount of ketone alkylation is much higher and that the reactions are faster in the presence than in the absence of surfactant aggregates. The hydrolysis of the halide is minimised in the presence of cationic or zwitterionic surfactants. Hydrophobic enolizable carbonyl compounds can be alkylated in aqueous alkaline surfactant solutions (see scheme) thus avoiding the traditional use of strong bases (such as NH2−, LDA, etc.) in aprotic solvents at very low temperatures (R, R1 = alkyl or phenyl group; R2= benzyl or cyclohexyl group).