Iminophosphinite pincer palladium complexes: Synthesis and application

Iminophosphinite pincer palladium complexes were synthesized and evaluated as potential catalysts in the Suzuki coupling reactions of phenylboronic acid and various aryl halides. The iminophosphinite ligands were synthesized through condensation reactions between 2-bromo-3-hydroxybenzaldehyde and 2,4,6-trimethylaniline and 2,6-diisopropylaniline, followed by phosphorylation with chlorodiphenylphosphine and chlorodicyclohexylphosphine. Oxidative addition of the pincer ligands to Pd2(dba)3 afforded palladium iminophosphinite complexes [(2-(CHNR)-6-(OPR′2)C6H3)PdBr] (R = 2,6-iPr2C6H3, R′ = Ph (2a) or Cy (2b); R = 2,4,6-Me3C6H2, R′ = Ph (2c) or Cy (2d)). Reaction of 2b and silver trifluoroacetate gave the corresponding iminophosphinite palladium trifluoroacetate (3). The solid state structures of 2a, 2d, and 3 were determined by X-ray single crystal diffraction studies.