Synthesis
To a stirred solution of 1-[(4-bromophenyl)methyl]-4-methylpiperazine (35.0 g, 130 mmol) in 1,4-dioxane (500 mL) was added potassium acetate (38.3 g, 390 mmol) and pinacol ester of bisboronic acid (33.0 g, 130 mmol) at room temperature. The mixture was evacuated and replaced with nitrogen (repeated three times). After addition of Pd(dppf)Cl2 (3.0 g, 1.3 mmol), the reaction mixture was stirred at 110 °C for 12 h under nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature and filtered to remove solids. The filtrate was concentrated and the residue was diluted with ethyl acetate and water. The organic layer was separated, dried with anhydrous Na2SO4 and concentrated. Purification of the residue by rapid column chromatography on silica gel (eluent ratio: DCM/MeOH = 50:1 to 10:1) afforded 4-(4-methyl-1-piperazinylmethyl)phenylboronic acid pinacol ester (37.0 g, 90% yield) as a brown solid.
References
[1] Patent: WO2015/32945, 2015, A1. Location in patent: Page/Page column 26; 27
[2] Patent: US2018/44328, 2018, A1. Location in patent: Paragraph 0162; 0174; 0175
[3] Patent: WO2012/119941, 2012, A1. Location in patent: Page/Page column 116
[4] Journal of Medicinal Chemistry, 2008, vol. 51, # 2, p. 196 - 218
[5] European Journal of Medicinal Chemistry, 2016, vol. 122, p. 684 - 701
