2,6-dichloro-3-Methoxyphenylboronic acid synthesis

Yield:851756-57-5 74%

Reaction Conditions:

Stage #1: 1,3-dichloro-4-methoxybenzenewith n-butyllithium in tetrahydrofuran at -78 - -65; for 30 h;
Stage #2: with Trimethyl borate in tetrahydrofuran at -78 - 20; for 16 h;
Stage #3: with hydrogenchloride;water in tetrahydrofuran; for 1 h;

Steps:

179

To synthesize compound 96, to 2,4-dichloroanisole (5 mL, 36 mmol) in THF (22 mL) at -78° C. was added 2.5 M nBuLi (17 mL, 43 mmol) keeping the temperature below -65° C. After 30 min, the reaction was poured into frozen (-78° C.) trimethylborate (14 mL, 215 mmol) followed by another portion of trimethylborate (10 mL, 90 mmol) and allowed to warm to room temperature over 16 h. The solid suspension was poured into a 1 N HCl aqueous solution and stirred for 1 h. The suspension was filtered to give 3.6 g (46%) of a white solid contaminated most likely with B(OH)₄. A second batch of crystals formed which were collected as an off-white solid that was compound 96 (5.8 g, 74%). ¹H NMR DMSO-d₆: δ 8.53 (s, 2H), 7.29 (d, J=8.8 Hz, 1H), 7.06 (d, J=8.8 Hz, 1H), 3.83 (s, 3H).

References:

US2005/245524,2005,A1 Location in patent:Page/Page column 102