Syntheses of novel 4-polyfluoroalkyl-substituted 5,6-oligomethylene pyrimidines

Article abstract of DOI:10.1055/s-2000-8200

2-Acylcycloalkanones having polyfluoroalkyl groups react with guanidine, urea, thiourea, methylisothiourea, benzamidine, guanylthiourea, dicyanodiamide, and trifluoroacetylurea by Lewis-acid catalysis to form the corresponding 5,6-oligomethylene pyrimidines. A decrease in the yields along with increase of polyflyoroalkyl substituent length in the molecule of the starting 1,3-diketone was observed in the case of reagents with lower nucleophilicity (urea, thiourea, dicyanodiamide). The pyrimidines obtained from aromatic aldehydes showed E-configuration with respect to the arylidene double bond. Tautomeric structures as a function of the substituent in 2 position in the pyrimidine ring both in liquid and solid state were investigated by X-ray diffraction, IR and NMR spectroscopy.