Methanol → 7-bromo-3-chloro-5-(2-methoxyethylidene)-5H-chromeno[2,3-c]pyridine
Reaction equation
[Br:1][C:2]1[CH:3]=[C:4]2[C:14](=[CH:15][CH:16]=1)[O:13][C:7]1[CH:8]=[N:9][C:10]([Cl:12])=[CH:11][C:6]=1[C:5]2([CH:18]=[CH2:19])O.[CH3:20][OH:21].S(=O)(=O)(O)O>>[Br:1][C:2]1[CH:3]=[C:4]2[C:14](=[CH:15][CH:16]=1)[O:13][C:7]1[CH:8]=[N:9][C:10]([Cl:12])=[CH:11][C:6]=1[C:5]2=[CH:18][CH2:19][O:21][CH3:20]Participants
4
Conditions
- Temperature
- 50 °C
Procedure
To a sealed vessel was added 7-bromo-3-chloro-5-vinyl-5H-chromeno[2,3-c]pyridin-5-ol (2.50 g, 7.38 mmol), methanol (59.8 mL, 1477 mmol) and sulfuric acid (0.2M in water) (3.70 mL, 0.74 mmol). The clear solution was heated to 50° C. over the weekend. The reaction mixture became light yellow heterogenous. The solvent was removed by rotovap and the residue was diluted with 125 mL of EtOAc. The organic solution was washed with saturated aqueous NaHCO3 and brine, dried over MgSO4, filtered and concentrated in vacuo to give the crude material 7-bromo-3-chloro-5-(2-methoxyethylidene)-5H-chromeno[2,3-c]pyridine (2.40 g, 6.81 mmol, 92% yield) as a yellow solid.