Yield:137504-86-0 86%

Reaction Conditions:

Stage #1:2-chloro-5-bromofluorobenzene with magnesium in tetrahydrofuran at 20 - 30; for 1 h;
Stage #2:Trimethyl borate in tetrahydrofuran at 0 - 10; for 2 h;

Steps:

1 1) Preparation of 3-fluoro-4-chlorophenylboronic acid
Add 36.5g (1.5mol) magnesium shavings to a 2000ml three-necked bottle,Add the prepared product to the bottle at a temperature of 20303-fluoro-4-chlorobromobenzene in tetrahydrofuran (207.9g (1.0mol) 3-fluoro-4-chlorobromobenzene, 415.8g tetrahydrofuran), Insulate for 1 hour after dropping.Organic solvent is mass ratio,There is no problem here.Add 156g (1.5mol) to another 2000ml three-necked bottleTrimethyl borate and 312g tetrahydrofuran,Drop the Grignard reagent prepared above at a temperature of 010,After dropping, keep warm for 2 hours,After insulation,Pour into a mixed solution of 208.5g concentrated hydrochloric acid and 417g water for hydrolysis,After hydrolysis, the tetrahydrofuran is removed under reduced pressure,filter,The resulting white filter cake was beaten once with toluene,After drying, the product is 149.6g,HPLC: 98.89%, yield 86.0%.

References:

CECEP Wanrun Co., Ltd.;Bai Zhongyuan;Xin Xing;He Xiaoqiang;Niu Panpan;Zhang Yiming;Wei Yulin CN111253210, 2020, A Location in patent:Paragraph 0012; 0013

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