Table 2 The evaluation of different solvents and reaction temperatures in the model reaction.

From: A straightforward, environmentally beneficial synthesis of spiro[diindeno[1,2-b:2′,1′-e]pyridine-11,3′-indoline]-2′,10,12-triones mediated by a nano-ordered reusable catalyst

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Entry

Solvent

Catalyst (mg)

Time, h

Temperature, °C

Isolated yield, %

1

DMF

MCM-41-SO3H (20)

1/3

100

94

2

DMF

MCM-41-SO3H (20)

2

60

74

3

DMF

MCM-41-SO3H (20)

1/2

80

90

4

n-hexane

MCM-41-SO3H (20)

12

Reflux

< 30

5

EtOAc

MCM-41-SO3H (20)

12

Reflux

< 30

6

CH3CN

MCM-41-SO3H (20)

4

Reflux

84

7

DMSO

MCM-41-SO3H (20)

1/3

100

94

8

EtOH

MCM-41-SO3H (20)

12

Reflux

65

9

Ball milling (solvent-Free)

MCM-41-SO3H (20)

10

RT

42

  1. Reaction conditions: isatin (1 mmol), 1,3-indanedione (2 mmol), aniline (1 mmol) and solvent (1 mL).
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