Uses
tert-Butyl 4-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)piperazine-1-carboxylate (cas# 470478-90-1) is a useful reactant for the preparation of 211At- and 125I-radiolabeled compounds.
Synthesis
Bis(pinacolato)diboron (2.3 g, 9.37 mmol) and potassium acetate (1.7 g, 17.59 mmol) were sequentially added to a stirred solution of 1-Boc-4-(4-bromophenyl)piperazine (2.0 g, 5.86 mmol) in 1,4-dioxane (40 mL) under argon protection. The reaction mixture was purged with argon for 15 min at room temperature. Subsequently, [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (428 mg, 0.58 mmol) was added and the reaction mixture was transferred to a sealed tube and the reaction was stirred for 6 hours at 110 °C. The reaction progress was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was diluted with water (50 mL) and extracted with ethyl acetate (2 x 50 mL). The organic phases were combined and washed sequentially with water (50 mL) and saturated saline (50 mL). The organic layer was dried with anhydrous sodium sulfate and concentrated under reduced pressure to afford the target product 4-[4-(N-BOC)piperazin-1-yl]phenylboronic acid pinacol ester (2.0 g, 5.15 mmol, 87% yield) as a white solid. NMR hydrogen spectrum (500 MHz, CDCl3): δ 7.7 (d, J=2.6 Hz, 1H), 6.90 (d, J=8.7 Hz, 2H), 3.6 (m, 4H), 3.2-3.3 (m, 4H).
References
[1] Patent: WO2017/117393, 2017, A1. Location in patent: Page/Page column 205; 206
[2] Patent: US2018/179183, 2018, A1. Location in patent: Paragraph 1274
[3] European Journal of Organic Chemistry, 2017, vol. 2017, # 3, p. 453 - 458
[4] Journal of Medicinal Chemistry, 2012, vol. 55, # 11, p. 5361 - 5379
[5] Patent: US2012/184520, 2012, A1. Location in patent: Page/Page column 18
