Synthesis of 4-(4-(dimethylamino)phenyl)-5-acetyl-6-phenyl-3,4-dihydropyrimidin-2(1H)-thione

4-(4-(dimethylamino)phenyl)-5-acetyl-6-phenyl-3,4-dihydropyrimidin-2(1H)-thione was prepared from benzoxyacetone (1) (1.62 g, 10 mmol), N,N-dimethylaniline (2) (1.21 g, 10 mmol) and thiourea (3) (1.140 g, 15 mmol) in dichloromethane (15 mL) as solvent using KF/Al₂O₃ (5 g) as a catalysis. The reaction mixture was heated under reflux conditions and stirred by using magnetic stirring until the one-pot addition was completed. The crude was filtered to remove residue on KF/Al₂O₃ and washed with DCM. The crude product was purified by column chromatography (silica gel, ethylacetate/n-hexane, 4:1, V/V as eluant) to give 4-(4-(dimethylamino)phenyl)-5-acetyl-6-phenyl-3,4-dihydropyrimidin-2(1H)-thione as pure yellow (4) (2.98 g, 85% yield).

Melting point: 118-120°C

UV (EtOH; λ_max nm): 340

IR (KBr, cm^-1): 3200 (N-H); 2951 (C-H Ar); 2853 (C-H); 2253; 1624; 1220

¹H-NMR (400 MHz, CDCl₃): δ= 3.48 (6H, s, N(CH₃)₂); 3.00 (1H, s, Benzyl-H); 2.48 (2H, brs, NH); 1.607 (3H, s, CH₃CO); 6.8 (2H, d, Ar-H); 7.1-7.3 (5H, m, Ar-H); 7.8 (2H, d, Ar-H).

¹³C-NMR (100 MHz, CDCl₃): δ= 190 (C=O); 184 (C=S); 175 (=C-N); 170 (-C-N); 154, 132, 129, 127, 125, 111, 40, 25

MS (m/z): 351 [M⁺]; 350; 308; 231.

Elemental Analysis: Calculated for C₂₀H₂₁N₃OS: C, 68.41%; H, 6.08%; N, 11.89%; O, 4.58%; S, 9.17%.

Found: C, 68.35%; H, 6.03%; N, 11.95%; O, 4.55%; S, 9.12%.