Hydrochloric Acid → 6-Methoxy-1H-indole-2-boronic acid, N-BOC protected

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Reaction Conditions

Reaction Steps

The above Boc-indole (3.08 g, 12.5 mmol) and isopropylborate (4.83 mL, 21.9 mmol) are dissolved in anhydrous THF (20 mL) and the solution is cooled at 0° C. While stirring, LDA (12.5 mL, 1.5 M mono-THF complex in cyclohexane, 18.7 mmol) is added dropwise. The mixture is stirred at 0° C. for 15 min and then room temperature for 0.5 h, followed by the addition of HCl (6 N, 3.0 mL, 18 mmol) in an ice-water bath. The organic solvent is removed in vacuo and the residue is suspended in H2O (100 mL) and acidified with HCl (6 N) to pH 4˜5. The precipitate is collected via filtration and washed with water and hexanes and dried in air to provide 1-Boc-6-methoxyindole-2-boronic acid (3.38 g, 93%).

Provenance & Evidence