To a stirred solution of N-[(3-aminooxetan-3-yl)methyl]-2-(1,1-dioxido-2,3-dihydro-1,4-benzothiazepin-4(5H)-yl)-6-methylquinolin-4-amine (200 mg, 0.46 mmol, prepared in analogy to Example 2-2), acetaldehyde (25.6 μL, 0.46 mmol) and acetic acid (270 μL) in methanol (8 mL) was added dropwize a solution of sodium cyanoborohydride (34 mg, 0.54 mmol) in tetrahydrofuran (0.5 mL). After being stirred for 12 hours at room temperature, the reaction mixture was diluted with ethyl acetate, washed with water and a saturated aqueous solution of sodium bicarbonate, dried over sodium sulfate, and concentrated in vacuo. The residue was purified by preparative HPLC to afford 42 mg of the desired product as a white solid (yield was 20%). MS obsd. (ESI+) [(M+H)+] 467, 1H NMR (400 MHz, DMSO-d6) δ ppm 7.95 (d, J=1.9 Hz, 1 H), 7.89-7.87 (t, J=2.2 Hz, 1 H), 7.64-7.58 (m, J=6.0 Hz, 2 H), 7.49-7.45 (m, J=4.0 Hz, 1 H), 7.35 (d, J=2.1 Hz, 1 H), 7.27-7.24 (m, J=2.5 Hz, 1 H), 6.17 (s, 1 H), 5.11 (s, 2 H), 4.52 (d, 2 H), 4.37 (d, 4 H), 3.62-3.45 (t, J=2.4 Hz, 2 H), 3.58 (d, 2 H), 2.53 (m, 2 H), 2.37 (s, 3 H), 1.07-1.03 (t, J=3.6 Hz, 3 H).
