Boron trifluoride etherate → 2-allyl-2-phenyltetrahydro-2H-pyran

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Reaction Steps

To a solution of 2-phenyltetrahydro-2H-pyran-2-ol (1.066 g, 5.98 mmol) and allyltrimethylsilane (1.901 mL, 11.96 mmol) in CH2Cl2 (25 mL) at 0° C. was added BF3.OEt2 (0.758 mL, 5.98 mmol) dropwise, and the mixture was stirred at the same temperature for 1 hr. Then the reaction was quenched with saturated NaHCO3 and the product was extracted with EtOAc. The extract was washed with brine, and the combined aqueous layers were back extracted with EtOAc once and combined. The extracts were dried over Na2SO4 and evaporated to give an oily residue. It was purified by Combiflash (80 g silica gel) eluting with 1:9 followed by 4:6 EtOAc-hexane to give 2-allyl-2-phenyltetrahydro-2H-pyran as oil (0.954 g). 1H NMR (400 MHz, CCl3D) δ ppm 7.10-7.45 (5H, m), 5.47-5.65 (1H, m, J=17.19, 10.11, 7.33, 7.33 Hz), 4.84-5.00 (2H, m), 3.64-3.78 (1H, m), 3.41-3.57 (1H, m), 2.35-2.48 (1H, m), 2.20-2.35 (1H, m), 1.55-1.81 (4H, m), 1.35-1.54 (2H, m).

Provenance & Evidence