Bropirimine

Bropirimine is an experimental drug with anti-cancer and antiviral properties. It is an orally effective immunomodulator and is being tried in bladder cancers.

Synthesis
For the first step, the dianion from malonic acid half-ester is formed by treatment with butyllithium. Acylation of the anion with benzoyl chloride proceeds at the carbanion, which is more nucleophilic (because of the higher charge density). This tricarbonyl compound decarboxylates on acidification to the β-ketoester. Condensation with guanidine leads to the pyrimidone. NBS mediated bromination then gives bropirimine.