Pyridine-2,6-dicarboxylic acid (10.0g, 59.9mmol) was added into ethanol (120mL),
then 3 drops of concentrated sulfuric acid were added. The mixture was heated to
reflux for 8 hours. After evaporation of the solvent, the solid residue was washed with
saturated Na2CO3 aqueous solution and extracted with chloroform for 3 times. The
organic phase was dried with small amount of MgSO4. The solvent was removed to
afford 1 as white powder (12.6g, 56.3mmol, yield = 94%). 1
H-NMR (400MHz,
CDCl3) |? ppm 8.29 (d, J = 7.80 Hz, 2H), 8.01 (t, J = 7.80, 7.80 Hz, 1H), 4.50 (q, J =
7.12, 7.12, 7.12 Hz, 2H), 1.47 (t, J = 7.13, 7.13 Hz, 3H). 13C-NMR (100 MHz, CDCl3)
|? ppm 164.6, 148.6, 138.2,127.8, 62.3,14.2,14.2. ESI MS: m/z = 224.1 [M+H]+
, 246.1
[M+Na]+
.
