This compound is a key synthetic intermediate in the manufacture of Pemetrexed (Alimta®), a multitargeted antifolate used in chemotherapy for non-small cell lung cancer and malignant pleural mesothelioma. It features the characteristic pyrrolo[2,3-d]pyrimidine core linked to a benzamide-glutamate moiety via an ethyl linker. Primarily employed in pharmaceutical synthesis and medicinal chemistry research, it enables efficient large-scale production and analog development targeting folate pathway enzymes such as dihydrofolate reductase (DHFR), thymidylate synthase (TS), and glycinamide ribonucleotide formyltransferase (GARFT). The diethyl ester and tosylate salt protect functional groups during synthesis, facilitating regioselective coupling and deprotection to yield the active diacid drug.