3,4-dihydro-2H-pyran → Methyl 3-bromo-4-(tetrahydro-2H-pyran-2-yloxy)benzoate

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Reaction Steps

To a stirred solution of 66.6E (38 g, 164 mmol) and 3,4-dihydro-2H-pyran (45 mL, 493 mmol) in DCM (355 mL,) was added 4-methylbenzenesulfonic acid hydrate (0.63 g, 3.30 mmol). The mixture was stirred at room temperature and monitored by TLC. After 2 hours, the solution was washed with a mixed aqueous solution of saturated aqueous sodium bicarbonate/brine/water (1:1:2). The aqueous layer was extracted three times with ether. After drying over anhydrous sodium sulfate and then filtering, the organic solvent was removed under reduced pressure. The crude material was purified on silica gel (0-10% EtOAc in hexanes) to yield a white solid. The product was recrystallized from MeOH to provide 66.6F (yield 90%). 1H NMR (400 MHz, CDCl3) δ ppm 8.24 (1H, d, J=2.0 Hz), 7.93 (1H, dd, J=8.6, 2.0 Hz), 7.17 (1H, d, J=8.6 Hz), 5.62 (1H, t, J=2.5 Hz), 3.90 (3H, s), 3.83 (1H, td, J=11.1, 2.9 Hz), 3.66 (1H, m), 2.18 (1H, m), 2.04 (1H, m), 1.94 (1H, m), 1.79 (2H, m), 1.67 (1H, m).)

Provenance & Evidence