1-Benzyl-1H-pyrazole-4-boronic acid pinacol ester

Chemical Properties

off-white to light yellow crystals or

Uses

1-Benzylpyrazole-4-boronic acid pinacol ester can be used:

• As a model compound in the study of the stability of boronate esters in different alcohols using the LCMS technique.
• As a substrate in the study of palladium-catalyzed methylation of heteroaryl boronate esters using iodomethane.
• As a substrate in the preparation of bromodifluoromethylthiolated arenes, applicable in the radiosynthesis of [¹⁸F]ArylSCF₃ compounds.

Synthesis

269410-08-4

100-39-0

761446-45-1

GENERAL STEPS: 4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (3.0 g, 15.5 mmol) was mixed with bromomethylbenzene (3.2 g, 18.7 mmol) in a solution of DMF (30 mL) containing K2CO3 (4.3 g, 31.2 mmol) and stirred at room temperature overnight. After completion of the reaction, the reaction mixture was diluted with EtOAc (50 mL) and H2O (50 mL), the organic layer was separated and washed with brine (50 mL). The organic layer was dried over Na2SO4, filtered and concentrated in vacuum. The residue was purified by silica gel column chromatography using PE/EtOAc (5:1) as eluent to afford the target compound 1-benzyl-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (3.5 g, 12.3 mmol) as a light yellow solid in 79% yield.1H NMR (400 MHz. CDCl3): δ 7.81 (s, 1H), 7.66 (s, 1H), 7.37-7.29 (m, 3H), 7.24-7.22 (m, 2H), 5.30 (s, 2H), 1.29 (s, 12H). lcms (M + H) + 285.

References

[1] Patent: US2018/296543, 2018, A1. Location in patent: Paragraph 0573; 0574; 0600
[2] Patent: WO2015/95767, 2015, A1. Location in patent: Page/Page column 284; 285
[3] Patent: WO2016/124508, 2016, A1. Location in patent: Page/Page column 55
[4] Journal of Medicinal Chemistry, 2016, vol. 59, # 4, p. 1370 - 1387
[5] Patent: WO2014/60395, 2014, A1. Location in patent: Page/Page column 35