Entry Aldehyde Grinding and heating methodb Ultrasound methodc Melting point (°C)
Time (min) Yield (%)d Time (min) Yield (%)d Found Reported [Ref. 22]
1 C6H5-CHO 15 95 5 97 185-186 183-185 [a,b]
2 4-Cl-C6H4-CHO 15 94 5 95 293-295 290-292 [a,b]
3 4-Br-C6H4-CHO 15 93 5 96 297-298 296-298 [a,b]
4 4-MeO-C6H4-CHO 20 88 8 90 206-208 203-206 [a,b]
5 4-NO2-C6H4-CHO 10 92 8 95 310-312 312-313 [a,b]
6 2-NO2-C6H4-CHO 15 86 5 88 296-298 293 [a,b]
7 Furfural 15 89 5 91 202-204 198-200 [c]
8 C6H5-CHO 22 92 10 95 301-304 305-307 [d,e]
9 4-Cl-C6H4-CHO 15 95 5 95 >320 330-332 [d,e]
10 4-Me-C6H4-CHO 22 94 10 95 301-303 304-307 [d,e]
11 4-Br-C6H4-CHO 15 90 5 93 >320 333-335 [d,e]
12 4-MeO-C6H4-CHO 18 88 8 90 >320 -
13 4-NO2-C6H4-CHO 12 92 6 95 >320 -
14 C6H5-CHO 15 88 5 90 208-210 202-203 [f]
15 4-Cl-C6H4-CHO 18 91 8 94 229-231 225-226 [f]
16 4-Me-C6H4-CHO 15 91 5 94 195-197 192-193 [f]
17 4-MeO-C6H4-CHO 20 85 8 89 230-232 225-226 [f]
18 4-NO2-C6H4-CHO 10 93 5 95 262-264 -
19 C6H5-CHO 15 90 5 92 311-314 311-314 [g]
20 4-Cl-C6H4-CHO 15 91 5 94 230-232 >330 [g]
21 4-Br-C6H4-CHO 15 90 5 92 >320 >330 [g]
22 4-Me-C6H4-CHO 18 88 8 91 198-200 314-316 [g]
23 4-MeO-C6H4-CHO 25 78 12 88 311-313 309-311 [g]
24 4-NO2-C6H4-CHO 12 94 5 95 >320 >330 [g]
aProducts were characterized by 1H NMR, IR and melting point and also by comparison with the reported in literature data.
b Reaction conditions: aldehyde, 1.0 mmol; substrate {2-naphthol (2 mmol), 2-hydroxynaphthalene-1,4-dione (2 mmol), mixture of 2-naphthol (1 mmol) and indane-1,3-dione( 1 mmol) or 2-hydroxynaphthalene-1,4-dione (1 mmol) and indane-1,3-dione(1 mmol); according to Scheme 2}; NSPVPHS, 10 mg; 60 °C, grinding under solvent-free conditions.
cReaction conditions: aldehyde, 1.0 mmol; substrate {2-naphthol (2 mmol), 2-hydroxynaphthalene-1,4-dione (2 mmol), mixture of 2-naphthol (1 mmol) and indane-1,3- dione(1 mmol) or 2-hydroxynaphthalene-1,4-dione (1 mmol) and indane-1,3-dione(1 mmol); according to Scheme 2}; NSPVPHS, 10 mg; room temperature and under ultrasound irradiation.
dIsolated yields
Table 4: D Synthesis of the xanthenes derivatives are catalyzed in presence of NSPVPHS.a