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ChemicalBook CAS DataBase List 4-PHENOXYPHENYLBORONIC ACID
51067-38-0

4-PHENOXYPHENYLBORONIC ACID synthesis

8synthesis methods
4-Bromodiphenyl ether (100 g, 0.402 mol)Was dissolved in anhydrous THF (800 mL)Under nitrogen protection,Cooled to -78 ° C,N-butyllithium (n-BuLi) (177 mL, 0.442 mol)The temperature is kept below -65 ° C,After stirring for 1 h,Continue to maintain the temperature -60 ,Triisopropyl borate (90 g, 0.482 mol) was added dropwise,Slowly rose to 0 ° C, stir for 3 h.Water (300 mL) was added under ice bath overnight. The reaction solution was concentrated to remove the organic phase,With 12N concentrated hydrochloric acid pH adjusted to 1 ~ 2,Precipitation of solids,Filtration and drying gave 4-phenoxyphenylboronic acid (77 g, yield 90%).
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Yield:51067-38-0 91%

Reaction Conditions:

Stage #1:Triisopropyl borate;4,4'-dibromodiphenyl ether with n-butyllithium in tetrahydrofuran;hexane at -70 - 20;Inert atmosphere;
Stage #2:water with hydrogenchloride in tetrahydrofuran;hexane at 0;Inert atmosphere;Solvent;

Steps:

1-5
Under nitrogen protection, mix the above 4,4'-dibromodiphenyl ether (16.4g, 0.05mol), tetrahydrofuran (160mL) and triisopropyl borate (10.3g, 0.055mol), and cool to -70°C to- At 60°C, start to add 44 mL of 2.5M n-butyl lithium hexane solution dropwise. After the dripping is completed, keep it warm and stir for 1 hour. Then it was naturally raised to room temperature and reacted overnight. After cooling, 1M hydrochloric acid was added for quenching, and the quenching process did not exceed 0°C. Extract twice with tetrahydrofuran (60mL), combine the oil layers, evaporate to dryness under reduced pressure, add ethyl acetate to re-dissolve, filter, and evaporate to dryness again. After beating with n-heptane/methyl tert-butyl ether (10/1), the off-white is obtained Solid 9.7 g, yield 91%, HPLC: 99.9%, HNMR structure is consistent.

References:

Cangzhou Purui Eastern Countries Technology Co., Ltd.;Zhang Jin;Leng Yanguo;Chang Zhiliang;Feng Xuemin;Meng Qingbin CN111072697, 2020, A Location in patent:Page/Page column 4-6

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