2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 7-Fluoro-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-(triisopropylsilyl)-1H-indole

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Reaction Conditions

Reaction Steps

7-Fluoro-1-(triisopropylsilyl)-1H-indole (4.0 g, 14 mmol) (Prepared according to M. Schlosser, et al, Eur. J. Org. Chem. 2006, 2956-2969) was dissolved in 30 mL dry THF, cooled to −75° C., treated in portions with sec-butyl lithium (10 mL, 1.4 M, 14 mmol) and stirred for 2 h at −75° C. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (3.0 mL, 2.7 g, 14 mmol) was added in portions and the mixture was stirred for 1 h at −75° C. The cooling was removed and the temperature was allowed to rise to 5° C. over 30 min. The reaction was quenched by addition of 5 mL sat. NH4Cl and partitioned between ethyl acetate and water. The organic phase was washed with sat. NaCl, dried (Na2SO4), evaporated onto silica gel, and purified by flash chromatography (SiO2; eluting with hexanes) to give 4.2 g of the title compound as a thick oil (4.2 g, 73%): 1H NMR (400 MHz, CDCl3) δ 7.43 (dd, J=7.9, 4.6 Hz, 1H), 7.38 (m, 2H), 1.75 (m, 3H), 1.38 (s, 12H), 1.13 (d, J=7.6 Hz, 18H). 19F NMR (376 MHz, CDCl3) δ −113.07. EIMS m/z 417.

Provenance & Evidence