Organic carbonates as alternative solvents for palladium-catalyzed substitution reactions.

Organic carbonates, such as propylene carbonate, butylene carbonate, and diethyl carbonate, were tested in the Pd-catalyzed asymmetric allylic substitution reactions of rac-1,3-diphenyl-3-acetoxy-prop-1-ene with dimethyl malonate or benzylamine as nucleophiles. Bidentate diphosphanes were used as chiral ligands. The application of monodentate phosphanes capable of self-assembling with the metal was likewise tested. In the substitution reaction with dimethyl malonate, enantioselectivities up to 98% were achieved. In the amination reaction, the chiral product was obtained with up to 83% ee. The results confirm that these "green solvents" can be advantageously used for this catalytic transformation as an alternative to those solvents usually employed which run some risk of being harmful to the environment.