Novel O N N Pyrazolyl-imine and Imidazolyl-imine Pincer Palladium Complexes as Heck Coupling Catalysts

Five pyrazolyl and imidazolyl compounds, 2,4-di-tert-butyl-6-(2-pyrazol-1-yl-ethylimino-methyl)-phenol (L1), 2,4-di-tert-butyl- 6-{(2-(3,5-dimethyl-pyrazol-1-yl)-ethylimino)-methyl}-phenol (L2), 2,4-di-tert-butyl-6-{(2-(1H-imidazol-4-yl)-ethylimino)- methyl}-phenol (L3), 4-tert-butyl-2-{(2-(1H-imidazole-4-yl)-ethylimino)-methly}-phenol (L4) and 2-{(2-(1H-imidazole-4-yl)- ethylimino)-methly}-phenol (L5) were synthesized by condensation of the appropriate 2-hydroxybenzaldehyde and the corresponding alkylamine. Reactions of L1-L5 with either (Pd(NCMe) 2 Cl 2 ) or (Pd(COD)MeCl) led to in situ deprotonation of the