Synthesis
Under nitrogen atmosphere, BINAP (187 mg, 0.3 mmol), Pd2(dba)3 (92 mg, 0.1 mmol), sodium tert-butoxide (1.19 g, 12.0 mmol), 4-hydroxypiperidine (Compound 8, 1.14 g, 11.2 mmol), and p-bromobenzotrifluoride (Compound 9, 1.36 mL, 10.0 mmol) were were dissolved in toluene. The reaction mixture was subjected to microwave radiation and reacted at 120°C for 1 hour. Upon completion of the reaction, the reaction solution was filtered through diatomaceous earth and the solids were washed with ethyl acetate. The filtrate and washings were combined and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluent: hexane-ethyl acetate gradient) to afford 1-(4-trifluoromethylphenyl)piperidin-4-ol (Compound 10, 1.45 g, 59% yield). The melting point of the product was 97-98 °C. 1H-NMR (CDCl3/TMS) δ ppm: 1.49-1.56 (m, 2H), 1.62-1.74 (m, 2H), 2.03 (brs, 2H), 3.03-3.10 (m, 2H), 3.63-3.71 (m, 2H), 3.93 (brs, 1H), 6.97 ( br, 2H), 7.48 (d, J = 8.7 Hz, 2H).
References
[1] Journal of the American Chemical Society, 2018, vol. 140, # 24, p. 7667 - 7673
[2] Angewandte Chemie - International Edition, 2017, vol. 56, # 42, p. 13088 - 13093
[3] Angew. Chem., 2017, vol. 129, p. 13268 - 13273,6
[4] Patent: EP1988077, 2008, A1. Location in patent: Page/Page column 63-64
[5] Patent: WO2010/115688, 2010, A1. Location in patent: Page/Page column 127
