Decarboxylation in the synthesis of 4-alkyl-, 4-alkenyl- and 4-acylpyrimidines

Decarboxylation of allylic esters of 4-carboxypyrimidines in toluene at 111 degreesC in the presence of a Pd(O) catalyst, gives a mixture of a 4-alkenylpyrimidine and a pyrimidine unsubstituted in the 4-position. If the decarboxylation is carried out in the presence of benzaldehyde, then benzaldehyde is added to the 4-position. Decarboxylation of 4-carboxypyrimidines in the presence of different electrophiles, results in incorporation of the electrophile into the 4-position together with a pyrimidine unsubstituted in the 4-position. Use of microwave irradiation enhances the rate of the decarboxylations.