A sealed tube equipped with a magnetic stirrer was charged with 142a (154.5 mg, 0.55 mmol), (2-(1-oxo-3,4,6,7,8,9-hexahydropyrazino[1,2-a]indol-2(1H)-yl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridin-3-yl)methyl acetate 113i (252.5 mg, 0.55 mmol), Pd(dppf)Cl2 (25.9 mg, 0.03135 mmol), NaOAc (108 mg, 1.1 mmol), K3PO4.3H2O (293 mg, 1.1 mmol), acetonitrile (6 mL), and water (0.5 mL). After three cycles of vacuum/argon flush, the mixture was heated at 110° C. for 2 h. It was then filtered and the filtrate was evaporated in vacuo. The residue was purified by silica gel column chromatography eluting with dichloromethane/methanol (15:1, V/V) to afford 142b (117 mg, 30%) as a brown solid. LCMS: [M+H]+ 540.2
