IMPROVEMENT ON THE SYNTHESIS OF (E)-ALK-3-ENOIC ACIDS

(E)-Alk-3-enoic acids have been prepared in high yield (85-90%) and ex cellent stereoselectivity (98-99%) by a modified Knoevenagel condensat ion of a straight carbon chain aldehyde with malonic acid, in dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) at 100 degrees C; in the presence of piperidinium acetate as catalyst. Condensation of the alde hyde with a monoester of malonic acid, under the above conditions, gav e the corresponding ester of (E)-alk-3-enoic acid in high yield (76-82 %) and good stereoselectivity (90-92%). Condensation of the aldehyde w ith cyanoacetic acid gave the beta,gamma-unsaturated nitrile in modera te yield (35-40%) without stereoselectivity.