Research Article
Solvent-Free Green and Efficient One-Pot Synthesis of Dihydropyrano[3,2-c]chromene Derivatives
Table 2
Synthesis of 2-Amino-4-aryl-3-cyano-5-oxo-4H,5H-pyrano[3,2-c]chromenes in solvent-free neat conditions using DABCO (5 mol%) as catalyst.
| Entry | Ar | Product | Time/min | Yield/% | m.p./°C Found (reported) |
| 1 | C6H5 | 4a | 30 | 94 | 256-257 (256–258) [15] | 2 | 4-O2N C6H4 | 4b | 30 | 96 | 259–261 (258–260) [15] | 3 | 3-O2N C6H4 | 4c | 30 | 93 | 261–263 (262–264) [15] | 4 | 4-ClC6H4 | 4d | 30 | 92 | 264–267 (263–265) [15] | 5 | 4-BrC6H4 | 4e | 30 | 91 | 247–250 (249–251) [15] | 6 | 4-CH3OC6H4 | 4f | 30 | 89 | 241–244 (240–242) [15] | 7 | 4-CH3C6H4 | 4g | 30 | 87 | 252–254 (250–252) [15] | 8 | 2,4-Cl2C6H3 | 4h | 30 | 90 | 256–258 (257–259) [15] | 9 | | 4i | 30 | 97 | 251–254 (252-253) [16] | 10 | | 4j | 30 | 96 | 226–230 (228) [20] |
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