To a solution of 9-cyclopentyl-9H-pyrido[4′,3′:4,5]pyrrolo[2,3-d]pyrimidin-2-amine (prepared as described in WO 2009/085185) (152 mg, 0.6 mmol) in dioxane (6 mL) were added tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (177 mg, 0.66 mmol), tris(dibenzylideneacetone)dipalladium (0) (28 mg, 0.030 mmol), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (52 mg, 0.090 mmol), and sodium t-butoxide (86 mg, 0.9 mmol). The reaction mixture thus obtained was heated at 150° C. under microwave irradiation for 1 hour. The reaction mixture was diluted with DCM, washed with brine, and then dried. The solvent was evaporated and the residue was purified by flash chromatography on silica gel eluting with 10% to 50% solvent A (DCM/MeOH/NH4OH, 100:10:1) in DCM to give the title compound as a light yellow solid (211 mg, 72% yield). 1H NMR (500 MHz, CDCl3) δ 1.52 (9H, s), 1.88-1.90 (2H, m), 2.14-2.21 (4H, m), 2.45-2.47 (2H, m), 2.92-2.94 (2H, m), 3.76-3.79 (2H, m), 4.59 (2H, m), 5.37 (1H, m), 7.49 (1H, d, J=10.0 Hz), 7.85 (1H, d, J=5.0 Hz), 8.14 (1H, br. s), 8.37 (1H, d, J=10.0 Hz), 8.52 (1H, d, J=5.0 Hz), 8.92 (1H, s), 9.11 (1H, s) ppm; LCMS m/z: 486 (M+1).
