5-Bromo-2-methylthiazole (2 g, 11.23 mmol) was dissolved in 70 mL of anhydrous tetrahydrofuran and cooled to -78 °C. A hexane solution (5.6 mL) of 2.4 M n-butyllithium was added slowly and dropwise under nitrogen protection, keeping the temperature at -78 °C. After stirring the reaction for 30 minutes, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2.5 g, 13.44 mmol) was added. The reaction was continued with stirring at -78 °C for 1.5 hours. Upon completion of the reaction, the reaction mixture was slowly warmed to room temperature. The reaction was quenched with a mixture of 10 mL of saturated aqueous ammonium chloride and 10 mL of water. The organic phase was separated by adding 50 mL of ethyl acetate for extraction. The aqueous phase was extracted once more with 30 mL of ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and the resulting residue was purified by silica gel column chromatography (elution system B) to afford the target product 2-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)thiazole (1.6 g, 64% yield) as a light yellow oil. Mass spectrum (ESI) m/z: 226.1 [M + H]+.
