| 79% |
With pyridinium chlorochromate; In dichloromethane; at 20℃; |
Description 20 : Dihydro-3(2H)-furanone; A mixture of 3-hydroxytetrahydrofuran (3.0 g, 0.034 mol) and pyridinium chlorochromate (14.7 g, 0.068 mol) in DCM (100 ml) was stirred at room temperature overnight. The title product was obtained by pouring the crude product through a silica pad using ethyl acetate as the eluent. The title product was obtained from 2 elutions (2.29 g; 79percent). 1H NMR (CDCI3) delta: 2.50 (2H, t), 3.87 (2H, s), 4.26 (2H, t). |
| 60% |
With acetic acid; pyridinium chlorochromate; In dichloromethane; at 20℃;Molecular sieve; Inert atmosphere; |
Pyridinium chlorochromate (6.5 g, 30 mmol, 1.5 equiv) was dissolved in 100 ml DCM at rt. Tetrahydro-3-furanol (1.6 ml, 20 mmol, 1 equiv) was added dropwise. 4 A molecular sieves (16 g) and glacial acetic acid (2 ml) were respectively added. The reaction mixture was stirred at rt overnight. A generous amount of Celite ? 545 was added and the solvent was removed by reduced pressure. The residue was then passed through a Celite ? 545 plug (10percent dichloromethane/diethyl ether) and the solvent was removed in vacuo. The residue was then purified by flash column chromatography (10percent dichloromethane/diethyl ether) to afford 3.45 (60percent yield). Spectral data correspond to that reported.24 1H NMR (400 MHz, CDCI3): delta 4.24 (t, J = 7.3 Hz, 2 H), 3.86 (s, 2 H), 2.48 (t, J = 7.3 Hz, 2 H). |
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With pyridinium chlorochromate; In dichloromethane; at 20℃; for 3.5h; |
Pyridinium chlorochromate (85.8 g, 3.5 eq) was added in portions over a period of 5 minutes to a solution of 3-hydroxytetrahydrofuran (10.02 g, 1.0 eq) in dichloromethane (115 mL). The reaction mixture was stirred at ambient temperature for 3.5 hours and then applied directly to a column of silica gel (325 g). The column was eluted with diethyl ether. The fractions containing product were combined and the solvent was removed by atmospheric distillation to provide 5.22 g of tetrahydrofuran-3-one |
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With pyridinium chlorochromate; In dichloromethane; at 40℃; for 16h; |
00182] Step 2: To a solution of tetrahydrofuran-3-ol (92.5 g, 1.05 mol) indichloromethane (2000 mL) was added pyridinium chlorochromate (454 g, 2.10 mol) and silicon gel (500 g). The reaction mixture was heated to 40°C. After 16 hours, the reaction mixture was filtered, and the filtrate was concentrated under reduced pressure to afford the crude residue. The residue was purified via chromatography on silica gel (methanol/DCM, linear gradient) to afford dihydrofuran-3(2H)-one. |
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With silica gel; pyridinium chlorochromate; In dichloromethane; at 40℃; for 16h; |
To a solution of tetrahydrofuran-3-ol (92.5 g, 1.05 mol) indichloromethane (2000 mL) was added pyridinium chlorochromate (454 g, 2.10 mol) and silica gel (500 g). The reaction mixture was heated to 40°C. After 16 hours, the reaction mixture was filtered, and the filtrate was concentrated under reduced pressure to afford the crude residue. The residue was purified via chromatography on silica gel (methanol/DCM, linear gradient) to afford dihydrofuran-3(2H)-one. |
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With pyridinium chlorochromate; In dichloromethane; at 0 - 20℃; |
b) dihydrofuran-3(2H)-one To a stirred solution of tetrahydrofuran-3-ol (3.0 g, 34 mmol) as obtained in step a) in DCM (60 mL) was added pyridiniumchloro chromate (14.65 g, 68 mmol) at 0 °C and the reaction mixture was stirred at rt for 16 h. Once the starting material was consumed (monitored by TLC), the reaction mixture was filtered through celite and the filtrate was washed with water, brine, drier over anhydrous Na2S04 and concentrated. The crude product (2.5 g) was used in the next step without further purification. |
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With tetrapropylammonium perruthennate; 4-methylmorpholine N-oxide; In dichloromethane; at 20℃; for 2h;Molecular sieve; |
Tetrapropylammonium perruthenate (TPAP, 20 mg, 0.057 mmol) was added to a mixture of tetrahydrofuran-3-ol (616 mg, 7.0 mmol), N-methylmorphorine N-oxide (NMO, 11 mmol), activated molecular sieve powder (3.5 g) in dichloromethane (30 mL) at room temperature, the reaction mixture was stirred at room temperature for 2 h, then filtered through a short pad of Celite under reduced pressure. The EPO <DP n="85"/>dichloromethane solution ( 20 mL) of dihydrofuran-3(2H)-one was used as a stock solution (0.3 M). |
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