92% |
With pyridinium p-toluenesulfonate; In dichloromethane; for 3h;Reflux; |
14-(Tetrahydro-2H-pyran-2-yloxy)-3,6,9,12-tetraoxatetradecyl 4-methylbenzenesulfonate (27) To a solution of 26 (2.613 g, 6.66 mmol) in DCM (100 mL) were added pyridinium p-toluenesulfonate (0.335 g, 1.33 mmol) and 2,3-dihydro-2H-pyran (0.91 mL, 9.99 mmol). The resulting mixture was refluxed for 3 h. After cooling the solution was concentrated under vacuum, poured into ice-water, and extracted with DCM. The combined organic layers were washed with water and brine, dried over MgSO4, filtered, and concentrated to give a yellow oil. The crude product was purified via silica flash chromatography using 4:1 EtOAc/Hex as an eluent, furnishing 27 (2.91 g, 92%): 1H NMR (300 MHz, CDCl3) δ 7.79 (d, J=8.2 Hz, 2H), 7.33 (d, J=8.2 Hz, 2H), 4.67-4.57 (m, 1H), 4.19-4.11 (m, 2H), 3.93-3.78 (m, 2H), 3.71-3.54 (m, 18H), 2.44 (s, 3H), 1.92-1.41 (m, 6H). |
79% |
With pyridinium p-toluenesulfonate; In dichloromethane; at 20℃; for 16h; |
Into a 250-mL round-bottom flask, was placed 14-[(4-methylbenzenesulfonyl)oxy]- 3,6,9,12-tetraoxatetradecan-1-ol (9.22 g, 23.493 mmol, 1 equiv) in dichloromethane (150 mL), to which was added DHP (2.17 g, 25.798 mmol, 1.10 equiv) and PPTS (1.18 g, 4.696 mmol, 0.20 equiv) in sequence. The resulting mixture was stirred for 16 hr at room temperature. The mixture was quenched by 100 mL water and extracted with ethyl acetate (50 mL x 3). The organic layers were combined, washed with brine, dried over anhydrous sodium sulfate and concentrated. The residue was applied onto a silica gel column eluting with ethyl acetate/petroleum ether (3/2). This resulted in 8.84 g (79%) of the title compound as a light yellow oil. MS (ES+): m/z 499.10 [MNa+] |
12.5 g |
With pyridinium p-toluenesulfonate; In dichloromethane; at 0 - 25℃; for 16h; |
To a solution of 2-[2-[2-[2-(2-hydroxyethoxy)ethoxy]ethoxy]ethoxy]ethyl 4- methylbenzenesulfonate (13 g, 33.12 mmol, 1 eq) in dichloromethane (100 mL) was added pyridine 4-methylbenzenesulfonate (416 mg, 1.66 mmol, 0.05 eq) and 3,4-dihydro-2H-pyran (3.34 g, 39.75 mmol, 3.63 mL, 1.2 eq) at 0C. Then the mixture was stirred at 25 C for 16 hours. The mixture was filtrated to get the filtrate. The filtrate was quenched by water (300 mL) and then diluted with dichloromethane (500 mL) and extracted with dichloromethane (500 mL x 2). The combined organic layers were washed with brine (300 mL), dried over, filtered and concentrated under reduced pressure to give a residue. The residue was purified by chromatography on silica gel (petroleum ether /ethyl acetate=3:l) to afford 2-[2-[2-[2-(2- tetrahydropyran-2-yloxyethoxy)ethoxy]ethoxy]ethoxy]ethyl 4-methylbenzenesulfonate (12.5 g, 26.23 mmol) as yellow oil. |