The aromatic azido group in anti-cancer drug design: application in the development of novel lipophilic dihydrofolate reductase inhibitors.
M. F. G. STEVENS, Robert Griffin, SUI-MING WONG · PubMed · 1987
Two properties of the aromatic azido group have been exploited in the design of a novel dihydrofolate reductase inhibitor--lipophilicity and biotransformability. 2,4-Diamino-5-(3-azido-4-chlorophenyl)-6-ethylpyrimidine (MZP, 4), which can be prepared in three high-yielding synthetic steps from the antimalarial drug pyrimethamine (1), has a pKa of 7.19, a log P of 2.81 and inhibitory activity against the P388, L1210, B16 and M5076 tumours in vivo. The ethanesulphonic acid salt of MZP (MZPES, 6) is a potent inhibitor of rat liver dihydrofolate reductase (Ki 1.60 nM) and L1210 cells in vitro. Injections of MZPES in water (10 mg ml-1) at pH 4.1 can be sterilised by filtration and are stable provided they are protected from light.