First heterogeneously palladium catalysed α-arylation of diethyl malonate

Pd exchanged NaY zeolites ([Pd(0)]-, [Pd(II)]- and entrapped [Pd(NH₃)₄]) exhibit a good activity towards the α-arylation of carbonyl compounds using different para-substituted aryl bromides. Low Pd-concentrations (only 2 mol%) are required to observe interesting activity. The catalysts can easily be separated from the reaction mixture and reused without any loss in activity. For large-scale applications the alternative use of an insoluble base as K₂CO₃ seems to be promising. The electronic nature of the aryl halides plays a limited role concerning the rate of the reaction.