Catalytic Asymmetric Alkylation in Water in the Presence of Surfactants

Abstract
Asymmetric palladium‐catalyzed alkylation of 1,3‐diphenyl‐2‐propenyl acetate with dimethyl malonate occurs in water in the presence of surfactants and a base. The efficiency as well as the enantioselectivity of the coupling reaction depend strongly on the nature and the concentration of the surfactant. The highest yield and enantioselectivity (up to 91%) was obtained using Binap as the ligand in the presence of a cationic surfactant, while neutral or zwitterionic surfactants gave poorer results; anionic surfactants gave no reaction at all. The best results were obtained using Na2CO3, NaHCO3, or K2CO3, among the bases used. The highest enantioselectivities were obtained when the reaction was performed in the presence of chiral atropoisomeric diphosphines such as Binap, Biphemp, or MeOBiphep. A supported cationic surfactant was also used successfully in this reaction, allowing an easier separation of the product.

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