An electrophilic iodocyclization reaction involving alkynylated 2-iodoanisoles and molecular iodine in the presence of sodium bicarbonate was developed and diiodo-functionalized benzo[b]furans were obtained in yields from 45 to 99%.
Keywords:
electrophilic iodocyclization; molecular iodine; diiodo-functionalized benzo[b]furans; functionalized heteroaromatics; diiodinated compounds
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|---|---|---|---|---|---|---|
| entry | I2 (equiv.) | Base (equiv.) | Solvent | Temperature / ºC | time / h | Isolated yield / % |
| 1 | 2 | - | CH2Cl2 | r.t. | 3 | < 5 |
| 2 | 2 | - | CH2Cl2 | r.t. | 12 | 34 |
| 3 | 2 | - | CH2Cl2 | 40 | 12 | 44 |
| 4 | 2 | NaHCO3 (2) | CH2Cl2 | 40 | 12 | 65 |
| 5 | 2 | K2CO3 (2) | CH2Cl2 | 40 | 12 | 51 |
| 6 | 2 | n-Bu4NI (2) | CH2Cl2 | 40 | 12 | 63 |
| 7 | 2 | NaHCO3 (2) | ClCH2CH2Cl | 70 | 12 | 82 |
| 8 | 2 | NaHCO3 (3) | ClCH2CH2Cl | 70 | 12 | 85 |
| 9 | 2 | NaHCO3 (3) | ClCH2CH2Cl | 70 | 24 | 89 |
| 10 | 3 | NaHCO3 (3) | ClCH2CH2Cl | 70 | 12 | 87 |
| 11 | 3 | NaHCO3 (3) | ClCH2CH2Cl | 70 | 24 | 97 |
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|---|---|---|---|
| entry | Alkynylated 2-iodoanisole (4) | Functionalized benzo[b]furan (5) | Isolated yield / % |
| 1 |
|
97 | |
| 2 |
|
71 | |
| 3 |
|
57 (92)b b this yield was obtained after 48 h of reaction. | |
| 4 |
|
46 (52)b b this yield was obtained after 48 h of reaction. | |
| 5 |
|
99 | |
| 6 |
|
75 | |
| 7 |
|
99 | |
| 8 |
|
69 | |
| 9 |
|
45 | |
