Phosphine-dependent stereoselective nucleophilic reaction to bicyclic bis-μ-dichloro-η³-allylpalladium complexes

The effects on ligands in nucleophilic reaction of η³-allyl- palladium chloride dimers were studied. Reaction of steroid 1 with Na ₂PdCl₄ in concentrated HCl under CO gave the cis,trans-bis-μ-dichloro-η³-allylpalladium complex 2 after recrystallization. Reaction of 2 with malonate anion in the presence of PPh ₃ afforded trans-3 in 65% yield. When Dppe was used, cis-3 was obtained as the major product. In nucleophilic reactions of bicyclic η³-allylpalladium chloride complex 4a or 4b with PPh₃, cis-5 was the major product. However, the reaction with Dppe gave trans-5 predominantly. The stereo-chemistry in the nucleophilic reaction of η³-allylpalladium chloride dimer is dependent on the added phosphines.