2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 3-[3,5-Difluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenoxy]tetrahydro-2H-pyran

To a mixture of 3-(3,5-difluorophenoxy)tetrahydro-2H-pyran (1.42 g, 6.63 mmol) in THF (26 mL) at −78° C., a solution of n-BuLi in hexanes (1.6 M; 10.4 mL, 16.6 mmol) was added slowly through a dripping funnel. When addition was complete, the mixture was kept at −78° C. for 1 h. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (4.06 mL, 19.9 mmol) was then added in one portion. The mixture was allowed to warm to room temperature and stirred for 1 h. The mixture was quenched with NaHCO3 solution and extracted with EtOAc. The organic extract was washed with brine, dried over Na2SO4, and concentrated under reduced pressure to give sub-title compound as a colorless oil. LCMS calc. for C17H24BF2O4 (M+H)+ m/z=341.2. found: 341.1.