Iodine → (3-Methoxyphenyl)boronic acid

Participants

Reaction Conditions

Reaction Steps

Magnesium turnings (10.4 g, 428 mmol) were placed in a three-necked flask equipped with one condenser and one addition funnel and the flask was flame-dried under a stream of nitrogen. Rubber septa were used to enclose the vessel and the reaction was run under a stream of nitrogen. A solution of 3-bromoanisole (40 g, 214 mmol) in THF (400 mL) was placed in the addition funnel. The magnesium turnings were covered with THF and warmed to 65° C. A crystal of iodine and then a few mL of the anisole solution were added to the turnings. A few minutes later the amber color disappeared. The anisole solution was then slowly dripped into the reaction vessel. After all of the anisole was added, the reaction was maintained at 65° C. for 2 h. After cooling to ambient temperature, the Grignard solution was poured into a solution of trimethylborate (24.96 g, 240 mmol) in diethylether (250 mL) and stirred for 1 h. The solution was quenched with 1N HCl and extracted with ether. The ether was removed by rotary evaporation leaving the boronic acid as an white solid (27.59 g, 181.51 mmol).

Provenance & Evidence