Asymmetric 1,4-addition of potassium aryltrifluoroborates [ArBF3]K to enones catalyzed by dicationic palladium(II) complexes

Asymmetric 1,4-addition of [ArBF3]K to cyclic and acyclic enones was carried out in aqueous methanol in the presence of a chiral phosphine-dicationic palladium(II) catalyst. A palladium complex of (S,S)-dipamp gave optically active beta-arylketones of up to 96 % ee for 2-cyclohexenone and 2-cycloheptenone. A palladium-(S,S)-chiraphos complex resulted in 82-97 % ee for 2-cyclopentenone and acyclic enones.