Modification of pyrimidine derivatives from antiviral agents to antitumor agents.

2,4-Diaminopyrimidine derivatives, that were originally developed as antiviral agents, were modified to antitumor agents by: (i) introducing an amino group at C-5 on the pyrimidine ring, (ii) changing the alkyl group and the ring size of the cycloalkyl group on the beta-position of the omega-hydroxyalkylamino group, (iii) replacing the phenylalkyl group on the cycloalkyl group with the 3,4,5-trimethoxyphenylalkyl group, (iv) the esterification of the primary alcohol with diethyl phosphate and (v) introducing the thiomethyl group at C-2 on the pyrimidine ring. Among the 21 compounds prepared, 6, which has cyclobutyl at the beta-position, exhibited potent activity towards P-388 leukemia. In addition, 14, with methoxyl groups on the phenyl ring and 17, with the thiomethyl group on the pyrimidine ring, showed specific inhibition for the EGFR protein kinase. Moreover, 15 and 16, which carry the diethyl phosphoryl group on the primary alcohol, exhibited inhibitory activity towards P-glycoprotein.