2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 2-[2-(Cyclopropylmethoxy)-5-(difluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

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반응 단계

2-Bromo-1-cyclopropylmethoxy-4-difluoromethyl-benzene (example B.b18; 24.35 g; 87.9 mmol) is dissolved in dry tert. BuOMe (440 mL). n-BuLi (1.6M in hexane; 60.0 mL; 96.0 mmol) is slowly syringed into the well stirred reaction mixture at −40° C. After one hour commercially available 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (17.86 g; 96.0 mmol) is added at −40° C. followed by stirring at 0° C. for one additional hour. The reaction mixture is quenched by addition of 2M aqueous citric acid (90.0 mL). The organic layer is separated, washed with brine, dried over Mg2SO4 and filtered through a pad of neutral alumina (act.2-3). The solvent is removed under reduced pressure to yield 28.1 g of the title compound as pale yellow oil.

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