Table 1 ¹H NMR chemical shifts of the intermediate products in the synthesis of 4-MMDPA

Dimethyl pyridine-2,6-dicarboxylate

8.32 (d, 2H, H₃)

8.05 (t, 1H, H₄)

4.01 (s, 6H, H₁)

2,6-Dimethoxycarbonyl-4-hydroxymethylpyridine

8.31 (s, 2H, H₃)

4.91 (s, 2H, H₅)

4.01 (s, 6H, H₁)

2,6-Dimethoxycarbonyl-

4-tosyloxymethylpyridine

8.17 (s, 2H, H₃)

7.81 (d, 2H, H_2’)

7.36 (d, 2H, H_3’)

5.19 (s, 2H, H₅)

4.01 (s, 6H, H₁)

2.45 (s, 3H, H_5’)

2,6-Dimethoxycarbonyl-

4-bromomethylpyridine

8.32 (s, 2H, H₃)

4.50 (s, 2H, H₅)

4.03 (s, 6H, H₁)

4-Mercaptomethyl-

2,6-pyridinedicarboxylic acid

8.28 (s, 2H, H₃)

3.86 (s, 2H, H₅)