Preparation method of 6-cyclopropylpyridine-3-boronic acid pinacol ester

The invention relates to a preparation method of 6-cyclopropylpyridine-3-boronic acid pinacol ester, which comprises the following steps: in a nitrogen atmosphere, adding 5-bromo-2-cyclopropylpyridine into anhydrous tetrahydrofuran, dropwise adding a Grignard reagent at room temperature, cooling to-15 DEG C after the raw materials are consumed, then dropwise adding 2-isopropyl boronic acid pinacol ester, naturally heating to 25 DEG C, reacting for 1-2 hours, cooling to-20 DEG C after the raw materials are completely consumed, cooling to-20 DEG C after the raw materials are completely consumed, and reacting for 1-2 hours to obtain 6-cyclopropylpyridine-3-boronic acid pinacol ester, thereby obtaining the 6-cyclopropylpyridine-3-boronic acid pinacol ester. Stirring and reacting; and pouring a TLC detection reaction liquid into the extract, stirring and separating the liquid, washing an organic phase with a saturated saline solution, drying and concentrating the organic phase after liquid separation, and carrying