2-Bromo-3-methylthiophene → 4,4,5,5-Tetramethyl-2-(3-methylthiophen-2-yl)-1,3,2-dioxaborolane

Participants

Reaction Steps

To a stirred solution of 2-bromo-3-methylthiophene (337 mg, 1.9 mmol) in 8 mL of THF at −40° C. was added n-BuLi (0.8 mL, 2.5 M/hexanes), and the reaction was allowed to stir for 30 min. At this time 2-isopropoxy-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (775 μL, 3.8 mmol) was added, and the reaction was allowed to warm to ambient temperature, and stirring was continued for 1 h. The reaction was then cooled to 0° C. and quenched with satd aq NaHCO3 (10 mL). The mixture was poured into EtOAc (100 mL), washed with H2O (2×50 mL), dried (Na2SO4) and concentrated in vacuo. Purification of the residue by silica gel preparative thin layer chromatography (20% EtOAc-hexanes) afforded 224 mg (53%) of the title compound as an oil. 1H-NMR (CDCl3; 400 MHz): δ 1.36 (s, 12H), 2.5 (s, 3H), 6.99 (d, 1H, J=4.8 Hz), 7.50 (d, 1H, J=4.8 Hz).

Provenance & Evidence