2-Aminopyridine → 2-(3,4-dimethoxyphenyl)-4H-pyrido[1,2-a]pyrimidin-4-one
Reaction equation
[C:1]([CH2:13][C:14]([O:16]CC)=O)(=O)[C:2]1[CH:11]=[CH:10][C:7]([O:8][CH3:9])=[C:4]([O:5][CH3:6])[CH:3]=1.[NH2:19][C:20]1[CH:25]=[CH:24][CH:23]=[CH:22][N:21]=1>>[CH3:6][O:5][C:4]1[CH:3]=[C:2]([C:1]2[N:19]=[C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][N:21]3[C:14](=[O:16])[CH:13]=2)[CH:11]=[CH:10][C:7]=1[O:8][CH3:9]Participants
3
Conditions
- Temperature
- 100 °C
Procedure
Ethyl veratroylacetate (4.5 g) was added dropwise under stirring at 60°-70° C. to a suspension of 2-aminopyridine (0.84 g) in polyphosphoric acid (13.7 g). The reaction mixture was stirred at 100° C. for 3 hrs and poured into ice-water (50 ml). The aqueous solution was extracted with chloroform, washed with water, dried and evaporated to give dark oily residue which was chromatographed on silica gel using n-hexaneethyl acetate. The fractions were evaporated and the resulting residue was triturated with ethanol-isopropyl ether to give 2-(3,4-dimethoxyphenyl)-4-oxo-4H-pyrido[1,2-a]pyrimidine (3.8 g).