Research Article
Triton-B-Catalyzed, Efficient, Solvent-Free Synthesis of Benzopyrans
Table 1
Conversion of substituted benzophenones into benzopyrans of general formula I a.
| Product | R1 | R2 | R3 | R4 | Time/min. | Yieldsb/% | Reference |
| 1 | H | H | CH3 | CH3 | 5 | 86 | [18, 19] | 2 | H | OH | CH3 | CH3 | 5 | 89 | [18, 19] | 3 | H | OH | CH3 | C2H5 | 8 | 85 | [20–22] | 4 | H | OH | R3 = R4 = Cyclopentyl | 7 | 88 | [23] | 5 | H | OH | R3 = R4 = Cyclohexyl | 6 | 90 | [24] | 6 | OH | H | CH3 | CH3 | 10 | 81 | [23] | 7 | OH | H | CH3 | C2H5 | 8 | 82 | [23] | 8 | OH | H | R3 = R4 = Cyclopentyl | 8 | 89 | [24] | 9 | OH | H | R3 = R4 = Cyclohexyl | 8 | 86 | [25–29] | 10 | NO2 | H | CH3 | CH3 | 8 | 85 | [18, 19] | 11 | OCH3 | H | CH3 | CH3 | 5 | 91 | [23] | 12 | OCH3 | OH | CH3 | CH3 | 5 | 92 | [18, 19] | 13 | OCH3 | OCH3 | CH3 | C2H5 | 4 | 94 | [24] | 14 | OCH3 | OCH3 | C2H5 | C2H5 | 4 | 99 | [25–29] | 15 | OCH3 | NO2 | -C2H5 | CH3 | 5 | 92 | [24] | 16 | OH | OCH3 | -C4H9 | -C4H9 | 5 | 83 | [20–22] |
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aAll the products were characterized by IR, NMR, and mass spectroscopic data.
bIsolated yields.
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