Palladium complexes of (benzoimidazol-2-ylmethyl)amine ligands as catalysts for methoxycarbonylation of olefins

• Palladium complexes were used as catalysts in methoxycarbonylation of olefins.
• Linear and branched esters were afforded with 100% chemoselectivity.
• Activity was dependent on acid promoter, alkene chain length and complex structure.
• Addition of PPh3 to the reaction mixture favoured linear esters.
• Higher alkenes gave more of the branched esters.

Reactions of N-(1H-benzoimidazol-2-ylmethyl)-2-methoxy aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl)-2-bromo aniline (L2) with either [PdCl2(COD)] or [PdClMe(COD)] afforded the neutral palladium complexes [PdCl2(L1)] (1), [PdClMe(L1)] (2) and [PdClMe(L2] (3), respectively. Treatment of 2 and 3 with one equivalent of PPh3 in the presence of NaBAr4 (Ar = 3,5-(CF3)2C6H3) produced the corresponding cationic species, [PdMe(L1)]BAr4 (4) and [PdMe(L2)]BAr4 (5). All the palladium complexes formed active catalysts in the methoxycarbonylation of alkenes to produce linear and branched esters. The catalytic behaviour was dependent on the catalyst structure, presence of PPh3, acid promoter and alkene chain length.

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