ChemicalBook CAS DataBase List 2,4-Difluorophenylboronic acid

2,4-Difluorophenylboronic acid synthesis

6synthesis methods

Product Name:2,4-Difluorophenylboronic acid
CAS Number:144025-03-6
Molecular formula:C6H5BF2O2
Molecular Weight:157.91

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Yield:144025-03-6 84.3%

Reaction Conditions:

with sulfuric acid in tetrahydrofuran;water;

Steps:

20.B Preparation of 2,4-difluorophenylboronic acid

B) Trimethylborate (25.98 g; 0.25 moles--Fluka) and a solution of 2,4-difluorophenylmagnesiumbromide (0.25 moles) in tetrahydrofuran (200 ml) were contemporaneously added, in 1 hour, into a reactor containing tetrahydrofuran (125 ml) under nitrogen while keeping the temperature at -15° C. At the end of the addition, the reaction mixture was kept under stirring at -15° C. for 15 minutes. After bringing the temperature to 0° C., water (17.5 ml) and 10% sulfuric acid (125 ml) were added in 10 minutes and in 15 minutes respectively. After adding further water (250 ml) up to complete dissolution, the solution was extracted with ethyl ether (3*150 ml). The collected organic phases were evaporated to dryness obtaining a crude 2,4-difluorophenylboronic acid (36.98 g; titre 90%; 84.3% yield) which was used in the subsequent cross-coupling reaction without any further purification.

References:

US5312975,1994,A