Quinoline, 8-methyl-, palladium complex

Zerovalent palladium complexes with the unsymmetric iVyV-ligands 8-(2-pyridyl)quinoline, 8-(6-methyl-2-pyridyl)-quinoline, or /ra j -4,5-bis(2-pyridyl)norbornane and ma or fn have been obtained from Pd2(dba)3, the chelating ligand. 

Pyridine- and quinolinecarboxylic acids. Methylpyridines and methyl-quinolines form complexes (1) with palladium chloride. These complexes can be oxidized by concentrated H2O2 at 80° and then hydrolyzed to the corresponding carboxylic acid (3). 

Both [Pd(OAc)2] and [Pd(acac)2] were used as catalyst precursors, in the presence of PPhs or PBu"3. No catalysis occurred here in absence of the phosphorus ligand. When isoprene was carbonylated using [Pd(OAc)2] and PPhj as catalyst precursor, dimerization of the alkene did not take place, the ester of 4-methyl-3-pentenoic acid being formed as the only product. Because of its potential application to the synthesis of esters for lubricating oils, the dimerization-carbonylation of butadiene has received special attention. Basic phosphines such as PBu°3 and weakly basic tertiary amine solvents (quinoline, N,N-diethylaniline) were found to improve both the stability and activity of the catalyst system.In a further report in which PPr 3 was used as phosphorus ligand it was found that the addition of maleic anhydride caused a marked increase in the catalytic activity. It was believed that through coordination it stabilized the palladium(O) complexes formed against precipitation as metal. ... 

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