Boron trifluoride etherate → 7-Bromo-4-chloro-5-(4-ethoxybenzyl)-2-methyl-2,3-dihydrobenzofuran

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Reaction Steps

To a solution of crude methanone 89 (3.15 g, 7.96 mmol) in CH2Cl2/CH3CN (25 mL/25 mL) were added triethylsilane (3.8 mL, 23.9 mmol) and boron trifluoride diethyl etherate (3.0 mL, 23.9 mmol) at 0° C. The mixture was warmed up to room temperature slowly and stirred at room temperature for 15 hours. To the mixture was added aq. saturated K2CO3 solution (70 mL) slowly and extracted with EtOAc (50 mL×2). The combined organic layer was dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by normal phase column chromatography to provide the desired product 90 (2.68 g, 85% (2-steps)).

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