Phosphorus sulfide (P2S5) → 3,4-dihydro-6-(3,4-dimethoxyphenyl)-1-ethyl-3-methyl-4-thioxo-2(1H)-pyrimidinone
Reaction equation
[CH3:1][O:2][C:3]1[CH:4]=[C:5]([C:11]2[N:16]([CH2:17][CH3:18])[C:15](=[O:19])[N:14]([CH3:20])[C:13](=O)[CH:12]=2)[CH:6]=[CH:7][C:8]=1[O:9][CH3:10].P12(SP3(SP(SP(S3)(S1)=S)(=S)S2)=S)=[S:23]>N1C=CC=CC=1>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([C:11]2[N:16]([CH2:17][CH3:18])[C:15](=[O:19])[N:14]([CH3:20])[C:13](=[S:23])[CH:12]=2)[CH:6]=[CH:7][C:8]=1[O:9][CH3:10]Participants
4
Procedure
A mixture of 6-(3,4-dimethoxyphenyl)-1-ethyl-3-methyl-2,4(1H,3H)-pyrimidinedione (0.80 g) and phosphorus pentasulfide (1.8 g) in pyridine (18 ml) was refluxed for 15 hours with stirring. The reaction mixture was evaporated under reduced pressure. The residue was washed with 1N-hydrochloric acid and extracted with dichloromethane. The extract was washed with water, dried over magnesium sulfate and evaporated under reduced pressure. The residue was triturated in diisopropyl ether to give 3,4-dihydro-6-(3,4-dimethoxyphenyl)-1-ethyl-3-methyl-4-thioxo-2(1H)-pyrimidinone (0.60 g).