5-Carboxy-2-methylphenylboronicacid

5-Carboxy-2-methylphenylboronicacid Property

Melting point:

157-167 °C

Boiling point:

446.8±55.0 °C(Predicted)

Density 

1.34±0.1 g/cm3(Predicted)

storage temp. 

Inert atmosphere,2-8°C

solubility 

DMSO (Slightly), Methanol (Slightly)

form 

Solid

pka

4.38±0.10(Predicted)

color 

White

Safety

HS Code 

2931900090

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H302Harmful if swallowed

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P270Do not eat, drink or smoke when using this product.

P301+P312IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell.

P330Rinse mouth.

P501Dispose of contents/container to..…

5-Carboxy-2-methylphenylboronicacid Chemical Properties,Usage,Production

Uses

5-Carboxy-2-methylphenylboronic Acid acts as a reagent in the synthesis of pyrazolopyridinone-based p38 MAP kinase inhibitor

Synthesis

To a 500 mL three-necked round-bottomed flask equipped with two dropping funnels and an argon inlet, 3-bromo-4-methylbenzoic acid (11.00 g, 51.2 mmol) and anhydrous THF (150 mL) were added under argon protection and stirred until complete dissolution. The reaction system was cooled to -78 °C and n-butyllithium (1.6 M hexane solution, 60.7 mL, 97.0 mmol) was slowly added dropwise through a dropping funnel. After the dropwise addition, the reaction continued to be stirred at -78 °C for 1 hour. Subsequently, trimethyl borate (17.7 mL, 159.0 mmol) was slowly added through a second dropping funnel. After addition, the reaction was maintained at -78 °C for 1 h. The reaction was slowly warmed to room temperature and stirred overnight. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The crude product was dissolved in ether and poured into 1N HCl aqueous solution. The aqueous phase was extracted with ether (3 x 150 mL), the organic phases were combined, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated to dryness. The crude product was purified by ISCO system (220 g silica gel column, hexane/ethyl acetate gradient elution followed by dichloromethane/methanol gradient elution). Impurities were eluted in hexane/ethyl acetate and the pure product was eluted in a methanol/dichloromethane (5:95) solvent system to afford the target product 5-carboxylic acid-2-methylphenylboronic acid (3.3 g, 33% yield). The product was characterized by 1H NMR (400 MHz, acetone-d6): δ 12.10 (br s, 1H), 8.16 (s, 1H), 7.90-7.63 (m, 1H), 7.11 (d, J=7.9 Hz, 1H), 2.42 (s, 3H).

References

[1] Angewandte Chemie - International Edition, 2010, vol. 49, # 8, p. 1492 - 1495
[2] Angewandte Chemie - International Edition, 2016, vol. 55, # 12, p. 3909 - 3913
[3] Angew. Chem., 2016, p. 3977 - 3981,5
[4] Patent: WO2014/144380, 2014, A1. Location in patent: Page/Page column 109; 110