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3. Results and Discussion3.1 Synthesis of Starting Material: BenzoylacetonePart-IIIResults and DiscussionBenzoylacetone was synthesized as per literature method 1 by reacting acetophenone andethylacetate in the presence of strong alkali such as sodium hydride or freshly preparedsodium methoxide under chilling conditions as given in the Scheme 1.OOOOO+EtONa0-2 o CEthyacetate Acetophenone BenzoylacetoneScheme-1Acylation of ketones with esters requires the presence of a strong base under anhydrousconditions. Ketones, where only one unique mesomeric carbanion formed (e.g.symmetrical ketones or alkyl aryl ketones) yield a single regioisomer. The reaction isillustrated by the formation of benzoylacetone from acetophenone and ethyl acetate andmay be outlined mechanistically in Scheme-2.OOOPh+ EtOHHOEtPh CH 2mesomeric anionPh CH 2OOOO+OEtOEtH 2 CPhPh-EtOHOOH 3 OOOPhPhScheme-2: Proposed mechanis for the synthesis of bezoylacetone3.2 Synthesis of Target Dihydropyrimidine Compounds (VIIi-xxx)The target compounds were synthesized following classical Biginelli reaction by reacting1,3-diketon (benzoylacetone), urea or thiourea and substituted aromatic aldehyde as asingle pot reaction in the presence of catalytic amount of conc. HCl as given in theScheme-2.454