2-Phenylquinolin-8-amine (60 mg, 0.27 mmol) was subjected to the same general amide coupling procedure outlined above using 1-(tert-butoxycarbonyl)piperidine-4-carboxylic acid. The resulting intermediate, namely tert-butyl 4-(2-phenylquinolin-8-ylcarbamoyl)piperidine-1-carboxylate, was further treated with 2 mL of 25% TFA in CH2Cl2 for 6 h. The reaction mixture was concentrated under reduced pressure. The resulting residue was purified by preparative HPLC (using aqueous CH3CN that has been buffered with 0.1% TFA) to afford 25 mg of the product. MS (ESI) calcd for C21H21N3O (m/z): 331.17. found: 332 [M+1].
