Table 3 Comparative performances of the Talc catalyst for the synthesis of dihydropyranochromene in different conditions.

From: Natural talc: a basic, cost-effective, and available catalyst for the one-pot synthesis of dihydropyranochromenes and pyranopyrazoles, along with related DFT calculations

Entry

Condition solvent/catalyst (g)

Condition

Time (min)

Yield (%)a

1

–/Talc (0.04)

Mixer Mil 10 Hz

20

Trace

2

–/Talc (0.04)

Mixer Mil 15 Hz

20

Trace

3

–/Talc (0.04)

Mixer Mil 20 Hz

20

Trace

4

–/Talc (0.06)

Mixer Mil 20 Hz

20

Trace

5

–/-

Reflux

90

Trace

6

H2O/-

Reflux

90

Trace

7

C2H5OH/-

Reflux

90

10

8

C2H5OH/Talc (0.01)

Reflux

90

43

9

C2H5OH/Talc (0.02)

Reflux

90

61

10

C2H5OH/Talc (0.04)

Reflux

90

78

11

C2H5OH/Talc (0.06)

Reflux

90

95

12

C2H5OH: H2O/Talc (0.04)

R.T.

120

57

13

C2H5OH/NaOH (0.04)

Reflux

20

50b

14

C2H5OH/K2CO3 (0.04)

Reflux

180

95b

15

C2H5OH/MgO (0.04)

Reflux

120

98b

16

C2H5OH/Hydrotalcite (0.04)

Reflux

150

95b

  1. The ratio of 4-nitrobenzaldehyde: malononitrile:4-hydroxycoumarine is 1 mmol: 1.2 mmol: 1 mmol.
  2. aIsolated Yield, bConversion yield.
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