Skip to main content

Table 2 Synthesis of PPz derivatives catalyzed by Nano-SiO2/AEP at room temperature and solvent-free conditionsa

From: A green protocol ball milling synthesis of dihydropyrano[2,3-c]pyrazole using nano-silica/aminoethylpiperazine as a metal-free catalyst

View full size image

Entry

Aldehyde

Time (min)

Yield (%)b

m. p. (°C)

Found

Reported (ref.)

1

4-Nitrobenzaldehyde

5

95

242–244

246–248 [32]

2

4-Chlorobenzaldehyde

5

93

230–231

235–237 [32]

3

3-Nitrobenzaldehyde

10

76

210–211

235–236 [32]

4

2,4-Dichlorobenzaldehyde

5

87

223–225

223–225 [33]

5

4-Fluorobenzaldehyde

5

96

212–214

212–214 [33]

6

4-Boromobenzaldehyde

5

97

178–180

179–181 [32]

7

3-Methoxy-4-hydroxybenzaldehyde

20

93

233–235

234–236 [33]

8

4-Hydroxybenzaldehyde

10

92

220–221

222–224 [33]

9

4-Methylbenzaldehyde

15

87

204–205

170–173 [32]

10

Benzaldehyde

20

90

241–243

243–244 [35]

11

3,4-Dihydroxybenzaldehyde

15

90

221–224

220–222 [32]

12

Furan-2-carbaldehyde

15

93

234–235

233–235 [32]

13

Pyrrole-2-carbaldehyde

20

94

210–213

-

14

2-Methoxybenzaldehyde

20

80

220–222

214–216 [32]

15

Cyclohexanecarbaldehyde

15

80

138–139

140–142 [32]

16

3-phenylpropionaldehyde

12

90

210–212

17

butyraldehyde

20

68

117–118

115–117 [32]

  1. aReaction conditions: ethylacetoacetate (1 mmol), hydrazine hydrate (1.5 mmol), malononitrile (1 mmol), and 4-nitrobenzaldehyde (1 mmol) were milled in a 10 mL stainless steel milling vial with two balls at 20 Hz for 5–20. bIsolated yield