SYNTHESIS AND BIOLOGICAL-ACTIVITY OF 4-AMINO-7-OXO-SUBSTITUTED ANALOGS OF 5-DEAZA-5,6,7,8-TETRAHYDROFOLIC ACID AND 5,10-DIDEAZA-5,6,7,8-TETRAHYDROFOLIC ACID

The 4-amino-7-oxo-substituted analogues of 5-deaza-5,6,7,8-tetrahydrof olic acid (5-DATHF) and 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (DDA THF) were synthesized as potential antifolates. Treatment of the alpha ,beta-unsaturated esters 11a-c, obtained in one synthetic step from co mmercially available para-substituted methyl benzoates (9a-c) and meth yl 2-(bromomethyl)acrylate (10), with malononitrile in NaOMe/MeOH affo rded the corresponding pyridones 12a-c. Formation of the pyrido[2,3-d] pyrimidines 13a-c was accomplished upon treatment of 12a-c with guanid ine in methanol. After the hydrolysis of the ester group present in 13 a-c, the resulting carboxylic acids 14a-c were treated with diethyl cy anophosphonate in Et3N/ DMF and coupled with L-glutamic acid dimethyl ester to give 15a-c. Finally, the basic hydrolysis of 15a-c yielded th e desired 4-amino-7-oxo-substituted analogues 16a-c in 20-27% overall yield. Compounds 16a-c were tested in vitro against CCRF-CEM leukemia cells. The results obtained indicated that our 4-amino-7-oxo analogues are completely devoid of any activity, the IC50 being higher than 20 mu g/mL for all cases except 14c for which a value of 6.7 mu g/mL was obtained. These results seem to indicate that 16a-c are inactive preci sely due to the presence of the carbonyl group in position C7, the dis tinctive feature or our synthetic methodology.