Table 5 Comparison of the catalytic activity of Fe–N–C/DDQ catalyst system in the oxidation of diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicarboxylate with some reported procedures.

1

NHPI (10 mol%)/Co(OA_C)₂ (0.5 mol%)

CH₃CN, O₂, Reflux

4 h

99

⁷⁴

2

Laccase (200 U)/4-phenyl urazole (20 mol%)

NaPBS/CH₃CN,O₂, 40 °C

22 h

99

⁷⁵

3

Laccase (168 U)/ABTS (10 mol%)

Acetate buffer/MeOH, air, 50 °C

9 h

80

¹⁰³

4

AuCNT (10 mol%)/2,5-dichlorocyclohexa-2,5-diene-1,4-dione (200 mol%)

CHCl₃/H₂O

36 h

78

¹⁰⁴

5

Fe–N–C (70 mg, 4.3 mol% of Fe), DDQ (10 mol%), O₂ (balloon)

H₂O/MeCN, R. T

6.51 h

94

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