Synthesis of 1,3-Disubstituted Hexahydropyrimidine Derivatives from Dibenzoylmethane, Acetylacetone, Ethyl Acetoacetate: One-Pot FeCl₃-Catalyzed Mannich Reaction

1,3-Disubstituted hexahydropyrimidin-5-yl(phenyl)methanone (products 1–5) were prepared from the reaction of dibenzoylmethane with primary amines and formaldehyde in the presence of Lewis acid catalyst at ambient temperature. Replication of the reaction with acetylacetone and ethyl aetoacetate yielded 1,1′-(1,3-disubstituted hexahydropyrimidine-5,5-diyl)diethanone (products 6–10) and ethyl 5-acetylhexahydropyrimidine-5-carboxylate (products 11–13), respectively. Yields obtained ranged from 69 to 89%.