Sub 1-3-1 (6.4g, 20mmol) was dissolved in anhydrous Ether, lowering the temperature of the reaction to -78??C, n-BuLi (2.5M in hexane) (1.4g, 22mmol) was added dropwise slowly, and after, the reaction It was stirred for 30 minutes. After lowering the temperature of the reaction back to -78??C dropwise Triisopropyl borate (5.6g, 30mmol). Stirring at room temperature, diluted with water and it binds the 2N HCl. After completion of reaction, ethyl acetate and water, dried over MgSO4 and the organic layer was extracted and recrystallized silicagel column and the resulting organic material and then concentrated to a Sub 1-4-1 4.5g (yield: 78%) was obtained.
