Triisopropyl borate → HCID 57898728, compound

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Reaction Steps

A solution of tert-butyl(2,4-dichloro-5-iodophenoxy)dimethylsilane (857 mg) obtained in Step 1 above in tetrahydrofuran (1 ml) and toluene (4 ml) was prepared under nitrogen atmosphere. The solution was cooled to −78° C. (dry ice/acetone). After triisopropylborate (0.6 ml) was added, n-butyllithium (1.6N; n-hexane solution, 1.62 ml) was added dropwise thereto over 5 minutes. The mixture was stirred at the same temperature for 30 minutes, and then warmed by removing the cold bath. When the inner temperature reached 0° C., 2,2-dimethylpropane-1,3-diol (0.27 g) was added to the solution and then warmed to room temperature. After stirring at room temperature for 8 hours, water (20 ml) was added to the solution and extracted with ethyl acetate (20 ml). The ethyl acetate solution was sequentially washed with a half-saturated aqueous ammonium chloride solution (15 ml), water (15 ml), and a saturated aqueous sodium chloride solution (10 ml). Then, the organic solution was pre-dried over anhydrous sodium sulfate. After filtration, the solvent was distilled off. The resulting residue was purified by silica gel column chromatography (developing solvent: n-hexane:ethyl acetate=20:1 to 9:1) to yield pale yellow oily 2-[5-(tert-butyldimethylsilanyloxy)-2,4-dichlorophenyl]-5,5-dimethyl[1,3,2]dioxaborinane (547 mg).

Provenance & Evidence