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

BMC Chemistry

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

Entry	Conditions	Time (min)	Yield^b (%) (refs.)
Entry	Solvent/temp (ºC)/catalyst	Time (min)	Yield^b (%) (refs.)
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/catalyst^a	15	92 (this work)^c
9	H₂O/EtOH/60/nano-SiO₂	15	40 (this work)
10	H₂O/EtOH/DBN	15	93 (this work)

ISSN: 2661-801X