Synthesis of Some New Folic Acid-Based Heterocycles of Anticipated Biological Activity

To date, no fused heterocycles have been formed on folic acid molecules; for this reason, and others, our target is to synthesize new derivatives of folic acid as isolated or fused systems. Folic acid 1 reacted with ethyl pyruvate, triethyl orthoformate, ethyl chloroformate, thioformic acid hydrazide, and aldehydes to give new derivatives of folic acid 2-6a,b. Moreover, It reacted with benzylidene malononitrile, acetylacetone, ninhydrin, ethyl acetoacetate, ethyl cyanoacetate, and ethyl chloroacetate to give the pteridine fused systems 10-15, respectively. Ethoxycarbonylamino derivate 5 reacted with some nucleophiles containing the NH₂ group, such as aminoguanidinium hydrocarbonate, hydrazine hydrate, glycine, thioformic acid hydrazide, and sulfa drugs in different conditions to give the urea derivatives 16-20a,b. Compound 4 reacted with the same nucleophiles to give the methylidene amino derivatives 21-24a,b. The fused compound 10 reacted with thioglycolic acid carbon disulfide, malononitrile, and formamide to give the four cyclic fused systems 25-30, respectively. The biological activity of some synthesized showed moderate effect against bacteria, but no effect shown towards fungi.