Methanol → Methyl 5-chloro-6-hydroxynicotinate
Reaktionsgleichung
[Cl:1][C:2]1[C:7](=[O:8])[NH:6][CH:5]=[C:4]([C:9]([OH:11])=[O:10])[CH:3]=1.OS(O)(=O)=O.[CH3:17]O>>[Cl:1][C:2]1[C:7](=[O:8])[NH:6][CH:5]=[C:4]([C:9]([O:11][CH3:17])=[O:10])[CH:3]=1Komponenten
4
Versuchsvorschrift
A mixture of commercially available 5-chloro-6-oxo-1,6-dihydropyridine-3-carboxylic acid (4.000 g; 23.04 mmol) and concentrated H2SO4 (0.3 ml) in anh. MeOH (52 ml) was refluxed, under nitrogen, for 19 h. MeOH was removed under reduced pressure, and the residue was basified by addition of a solution of 10% aq. NaHCO3. The mixture was then extracted with DCM (5×), and the mixed organic layers were dried over anh. MgSO4, filtered, and concentrated to dryness under reduced pressure affording methyl 5-chloro-6-oxo-1,6-dihydropyridine-3-carboxylate as a pale yellow solid. LC-MS (conditions D): tR=0.61 min.; [M+H]+: 187.93 g/mol.