Reactions of π-Allylic Palladium(II) Complexes of Acetoacetate Esters with Pyridine and Its Derivatives

The π-allylic palladium(II) complexes of ethyl and benzyl acetoacetate esters react with pyridine and its derivatives to afford the terminal-carbon-bonded complexes PdCl(CH2COCH2COOCH2R)L2, where R=CH3 or C6H5, and L=pyridine or its derivative. The NMR spectra unequivocally establish the bonding type in these complexes. The pyridine and 4-methylpyridine complexes are a mixture of cis and trans isomers in a ratio of 1: 5, while 2-methyl- and 2,6-dimethyl-pyridine complexes are trans exclusively. The relative stabilities of these complexes are compared.