3-Dimethylaminophenylboronic acid synthesis

Yield:178752-79-9 61%

Reaction Conditions:

Stage #1:3-bromo-N,N-dimethylaniline with n-butyllithium;Trimethyl borate in tetrahydrofuran;hexanes at -78 - -20; for 1.41667 h;
Stage #2: with hydrogenchloride in tetrahydrofuran;hexanes;water for 0.0833333 h;

Steps:

10.a
3-Bromo-N,N-dimethylaniline (500 mg, 2.50 mmol) was dissolved in THF (8 mL) and the solution was cooled to -78° C. n-Butyllithium (1.6M in hexanes, 1.56 mL, 3.75 mmol) was added drop-wise at -78° C. and the reaction mixture was stirred at this temperature for another 5 min. Trimethylborate (1.11 mL, 10.0 mmol) was added and the mixture was stirred for 1 h at -78° C. and was then left to warm to -20° C. over a period of 20 min. 2M HCl (3 mL) was added and the mixture was stirred for 5 min and was then neutralized by the addition of sat. NaHCO₃ solution. The mixture was extracted with AcOEt (3×10 mL) and the combined organics were concentrated under reduced pressure to provide the crude boronic acid. Flash chromatography on silica gel eluting with acetone/CH₂Cl₂ 1:1 provided 3-dimethylaminophenylboronic acid (251 mg, 61%).

References:

Kelly, Martha;Lee, Younghee;Liu, Bin;Fujimoto, Ted;Freundlich, Joel;Dorsey, Bruce D.;Flynn, Gary A.;Husain, Arifa US2006/270686, 2006, A1 Location in patent:Page/Page column 26

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