To a mixture of N-(piperidin-4-yl)-5,6,7,8-tetrahydro-benzo[4,5]thieno[2,3-d]pyrimidin-4-amine (2.86 g, 10 mmol) and 3-fluorophenylacetophenone (1.38 g, 10 mmol) in dry DCM (25 mL) was added titanium isopropoxide (2.85 g, 10 m.mol) at room temperature and stirred for 24 h. 1 M solution of diethylaluminumcyanide in toluene (1.2 mL, 10 mmol) was added to the above solution and the mixture was allowed to stir for 24 h. The reaction was quenched by the addition of saturated aq. NaHCO3 solution (15 mL) and the organic layer was separated, dried and concentrated under reduced pressure to get the title compound (4.3 g, 100%) as pale yellow powder. 1H NMR (400 MHz, CDCl3): δ 8.01 (s, 1H), 7.35-7.24 (m, 2H), 6.99 (t, 1H), 6.78 (t, 1H), 4.21 (brs, 1H, NH), 3.91-3.86 (m, 1H), 3.11-3.03 (m, 2H), 2.91 (t, 2H), 2.49-2.27 (m, 4H), 2.00-1.92 (m, 4H), 1.42 (s, 3H). MS (ESI) m/z: Calculated: 435.56; Observed: 436.2 (M++1).
