Zeolites as base catalysts: Condensation of benzaldehyde derivatives with activated methylenic compounds on Germanium-substituted faujasite

The condensation of benzaldehyde, 2-nitrobenzaldehyde, and 2-trifluoromethylbenzaldehyde with ethyl cyanoacetate and ethyl malonate to obtain intermediates for the production of dihydropyridine derivatives has been carried out on NaX-type zeolites. The substitution of Si by Ge during the zeolite synthesis results in a strong increase in activity, which has been related to changes in basicity. High activities and selectivities are obtained with the NaGeX zeolite when operating in a batch reactor at moderate temperatures. This zeolite is more active than pyridine and less active than piperidine.