Reaction Steps
A mixture of 4-[bromo-(4-diethylcarbamoyl-phenyl)-methylene]-piperidine-1-carboxylic acid tert-butyl ester (1a, 451 mg, 1.0 mmol), 3-carboxyphenyl boronic acid (330 mg, 2.0 mmol), 2M Na2CO3 (3 mL), and tetrakis(triphenyl phosphine) palladium(0) (25 mg) in toluene (degassed, 10 mL) and ethanol (degassed, 10 mL) was refluxed at 90° C. for 4 hrs under N2. The reaction mixture was then quenched with aqueous NH4Cl after cooling down to 0° C., and extracted with ethyl acetate (2×50 mL). The combined organic phases were washed with brine, dried over MgSO4, and evaporated to give a crude product, which was purified by flash silica gel column to provide the desired compound 2a (345 mg, 70%): 1H NMR (CDCl3) δ 1.15 (3 H, br m, CH3CH2—), 1.23 (3 H, br m, CH3CH2—), 1.47 (9 H, s, C(CH3)3), 2.31 (2 H, m, piperidine CH—), 2.35 (2 H, m, piperidine CH—), 3.30 (2 H, br m, CH3CH2N—), 3.48 (4 H, m, piperidine CH—), 3.54 (2 H, br m, CH3CH2N—), 7.14 (2 H, d, J=8.0 Hz, ArH), 7.24 (1 H, m, ArH), 7.33 (2 H, d, J=8.0 Hz, ArH), 7.42 (1 H, t, J=7.6 Hz, ArH), 7.86(1 H, s, ArH), 7.97 (1 H, d, J=7.6 Hz, ArH). IR (NaCl)2976, 1718, 1691, 1598, 1430, 1233, 1166 cm−1.
