Synthesis, Structural Studies, and Catalytic Application of Palladium Complexes Containing Anilido-Oxazolinate Ligands

A series of palladium anilido-oxazolinate complexes 18 prepared from ligand precursors HNArOxa [ortho-C6H4(NHAr)(4,4-dimethyl-2-oxazoline) where Ar = 2,4,6-trimethylphenyl, HNPhTriMeOxa; 2,6-diisopropylphenyl, HNPhDiiPrOxa; phenyl, HNPhHOxa; 2-methoxyphenyl, HNPhOMeOxa; 2-methylthiophenyl, HNPhSMeOxa] is reported. Treatment of HNArOxawith 1.1 equiv. Pd(OAc)2 afforded palladium(II) acetate complexes (NPhTriMeOxa)Pd(?2-OAc) (1) and (NPhDiiPrOxa)Pd(?2-OAc) (2) as monomeric complexes, [(NPhHOxa)Pd(OAc)]2 (3) as an anilido-bridged dinuclear complex, [(NPhOMeOxa)Pd(OAc)]2 (4) as an acetate-bridged dinuclear complex, and (NPhSMeOxa)Pd(OAc) (5) as a monomeric complex. The reactions of 2, 4, and 5 with an excess of NaCl(aq.) in acetone yielded palladium(II) chloride complexes, [(NPhDiiPrOxa)Pd(Cl)]2 (6) as a chloro-bridged dinuclear complex, (NPhOMeOxa)Pd(Cl) (7) as a monomeric complex, [(NPhOMeOxa)Pd(Cl)]2 (7') as an anilido-bridged dinuclear complex, and (NPhSMeOxa)Pd(Cl) (8) as a monomeric complex. The crystal and molecular structures of 18 are reported, and their application towards Suzuki and Heck reactions with a wide range of aryl halides has been examined.