To a mixture of 2-{1-[1-(4-methoxy-benzenesulfonyl)-piperidin-4-ylamino]-ethyl}-3-methyl-3H-quinazolin-4-one (183 mg, 0.4 mmol), formaldehyde (39 μL, 0.48 mmol, 37% wt. solution in water) and DMF (1 mL) was added MP-Cyanoborohydride (300 mg, 2-3 mmol/g) and the reaction was stirred overnight at room temperature. The reaction mixture was then filtered and purified by HPLC to yield the product. HPLC ret. time 2.41 min, 10-99% CH3CN, 5 min run; 1H NMR (400 MHz, CDCl3) δ 8.28 (d, J=8.0 Hz, 1H), 7.93 (t, J=7.2 Hz, 1H), 7.68 (m, 4H), 7.03 (d, J=8.6 Hz, 2H), 4.93 (m, 1H), 3.98 (s, 1H), 3.89 (s, 3H), 3.69 (s, 3H), 3.10 (s, 3H), 2.58 (m, 2H), 2.21 (m, 2H), 1.78 (d, J=6.6 Hz, 3H), 1.31 (m, 4H); ESI-MS m/z 471.3 (M+1)+.
