Under argon protection, 17.1 g (0.10 mol) of PinB (DMA) was added to a 500 mL reaction flask containing 100 mL of tetrahydrofuran. The temperature of the reaction system was lowered to 0~5°C and 44.3 mL of a 2.5 M solution of n-butyllithium (0.11 mol) was slowly added dropwise and stirred for 30 minutes keeping the temperature at 0~5°C. The reaction system was then warmed to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, the reaction was quenched by slow dropwise addition of 200 mL of 1 M KH2PO4 buffer and then extracted three times with 150 mL of ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate, and the organic phase was concentrated. To the concentrate was added 40 g of n-hexane and filtered to give 12.9 g of white solid product in 70% yield and >97% GC purity. The 1H NMR, 11B NMR and IR spectra of the product were consistent with those of the standard.
