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Table 4 Comparison of nano-SiO2/DBN catalyst with some other catalyst for the synthesis of 4b

From: Nano-SiO2/DBN: an efficacious and reusable catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran derivatives

Entry Conditions Time (min) Yieldb (%) (refs.)
Solvent/temp (ºC)/catalyst
1 CH2Cl2/60/SiO2/NH2OAc 360 90 [28]
2 H2O/80/Fe3O4@SiO2/DABCO 25 90 [29]
3 EtOH /reflux/l-Proline 360 87 [30]
4 EtOH /reflux/SO42−/MCM-41 60 80 [31]
5 H2O/reflux/DABCO 150 68 [32]
6 H2O/120/SDS 120 85 [33]
7 H2O/60/Thiourea dioxide 13 93 [34]
8 H2O/EtOH/60/catalysta 15 92 (this work)c
9 H2O/EtOH/60/nano-SiO2 15 40 (this work)
10 H2O/EtOH/DBN 15 93 (this work)
  1. aNano-SiO2/DBN
  2. bIsolated yield
  3. cThe modified condition