Table 2 Investigation of catalytic behavior of Fe3O4@SiO2@PCLH-TFA and its relative intermediates and some known catalysts upon the synthesis of 1f.

From: Synthesis of triarylpyridines with sulfonate and sulfonamide moieties via a cooperative vinylogous anomeric-based oxidation

Entry

Catalyst

Load of catalyst

Yield (%)

1

Fe3O4

10 mg

30

2

Fe3O4@SiO2

10 mg

25

3

PCL

10 mol%

45

4

Fe3O4@SiO2@PCL

10 mg

58

5

Fe3O4@SiO2@PCLH-TFA

10 mg

84

6

Trifluoroacetic acid

10 mol%

55

7

p-Toluenesulfonic acid

10 mol%

80

8

FeCl3

10 mol%

33

9

Trityl chloride

10 mol%

Trace

10

H2SO4

10 mol%

Trace

11

NH2SO3H

10 mol%

65

12

Fe (HSO4)3

10 mol%

52

13

Al (HSO4)3

10 mol%

36

14

Ca (HSO4)2

10 mol%

44

15

Silica sulfuric acid113

10 mg

71

  1. Reaction conditions: 4-Cholorobenzaldehyde (1 mmol, 0.140 g), 4-acetylphenyl-4-methylbenzenesulfonate (2 mmol, 0.580 g), and ammonium acetate (1.5 mmol, 0.115 g), solvent-free, 110 °C, 45 min.
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