Synthesis and characterization of enantiopure chiral NH/SO palladium complexes.

A series of enantiopure chiral NH/SO palladium complexes have been synthesised with high yields by treating the corresponding -butylsulfinamide/sulfoxide derivatives with Pd(CHCN)Cl. The enantiopure chiral ligands were prepared by stereoselective addition of -butyl or phenyl methylsulfinyl carbanions to different -butylsulfinylimines. In all cases, coordination occurs with concomitant desulfinylation. X-ray studies of the Pd complexes showed a higher influence of the phenylsulfinyl group in comparison to that of the -butylsulfinyl group. Furthermore, we have obtained and characterised two possible palladium amine/sulfonyl complexes, epimers at sulfur, resulting from -desulfinylation and coordination of palladium with both oxygens of the prochiral sulfonyl group. The catalytic activity and enantioselectivity of the new Pd(II) complexes of acetylated amine/-butyl- and phenylsulfoxides in the carboxylated cyclopropanes arylation reaction has been studied, obtaining the best results with the phenylsulfoxide ligand 25(SC,SS) that produced the final arylated product in a 93 :7 enantiomeric ratio.