To a mixture of (R)-(1-amino-but-3-ynyl)-7-chloro-3-phenylamino-3H-quinazolin-4-one (4.60 g, 12.2 mmol) and diisopropylethylamine (DIPEA) (5.5 ml) in dichloromethane (60 ml) was added a solution of 3-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-propionaldehyde (2.45 g, 12.1 mmol) in dichloroethane (10 ml), followed by a solution of sodium triacetoxy borohydride (NaBH(OAc)3) (0.25M in dichloroethane, 100 ml). The reaction mixture was stirred at room temperature and the reaction progress was monitored by HPLC/MS. Upon completion, a saturated sodium carbonate solution (100 ml) was added. The resulted organic layer was collected and washed with brine solution. The solvent was removed and residue was purified by flash column to afford 2-{3-[(R)-1-(7-chloro-4-oxo-3-phenylamino-3,4-dihydro-quinazolin-2-yl)-but-3-ynylamino]-propyl}-isoindole-1,3-dione (6.1 g, 95%) as off-white solid. M.p. 78-80° C. LCMS: m/e 526 [M+H]. 1H NMR (DMSO-d6): δ 9.09 (s, br, 1H), 8.07 (d, J=8.8 Hz, 1H), 7.74 (m, 1H), 7.83-7.76 (m, 5H), 7.58 (dd, J=8.8 and 2.0 Hz, 1H), 7.17 (t, J=7.6 Hz, 2H), 6.83 (brm, 1H), 6.65 (m, 2H), 4.1 and 4.0 (s, s, br, 1H, rotomers), 3.6 (t, J=6.8 Hz, 2H), 2.75 (s, br, 1H), 2.67-2.52 (brm, 2H), 2.35 (brm, 2H), 1.67 (brm, 2H).
