Pd(OAc)2/dppp, an efficient catalytic system for the oxidative esterification of benzaldehyde using organic halides as oxidants

The Pd-catalyzed oxidative esterification of benzaldehyde with methanol using organic halides as oxidant agents is reported. Our results demonstrate the crucial role of the ligand in the choice of the oxidant for this reaction. Phenyl bromide can be used as oxidants by using dppp as ligand. On the other hand, benzyl bromide is much more selective when PPh3 is used as the ligand. We were able to detect the key benzyl palladium intermediate in the catalytic cycle by using ESI-MS-(+). We also performed a one-pot CBr reduction/aldehyde oxidative esterification without the need for external oxidant agents.