Biginelli condensations of fluorinated 3-oxo esters and 1,3-diketones

Condensation of fluorinated 3-oxo esters or 1,3-diketones with benzaldehyde and (thio)urea results in the diastereoselective formation of 4-fluoroalkyl-4-hydroxy-2-oxo(thioxo)-6-phenyl-hexahydropyrimidine-5-carboxylates from which by dehydration under acidic conditions the corresponding 6-fluoroalkyl-2-oxo(thioxo)-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates were obtained. Under the same conditions, hexafluoroacetylacetone furnishes 4,6-dihydroxy-4,6-di(trifluoromethyl)-hexahydropyrimidin-2-one. Some further reactions of these pyrimidine derivatives leading to fused heterocycles are described.