Table 2 Synthesis of tetrahydrobenzo[a]xanthen-11-ones in the presence of Co3O4@SiO2/OS-SO3H.

From: Magnetic cobalt oxide supported organosilica-sulfonic acid as a powerful nanocatalyst for the synthesis of tetrahydrobenzo[a]xanthen-11-ones

Entry

Aldehyde

Time (min)

Yield (%)

M. P. (°C)

Found

Reported

1

C6H5

40

95

150–151

152–15463

2

4-NO2-C6H5

35

97

182–184

180–18163

3

4-Br-C6H5

35

95

183–185

185–18755

4

2,4-Cl-C6H5

45

91

180–182

179–18155

5

2-NO2-C6H5

40

90

223–225

221–22464

6

2-Cl-C6H5

35

95

173–175

174–17664

7

4-MeO-C6H5

50

92

199–202

201–20365

8

4-HO-C6H5

50

90

221–222

220–22565

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