A 50-mL round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 153a (200 mg, 0.68 mmol), bis(pinacolato)diboron (Pin2B2, 863 mg, 3.40 mmol), Pd2(dba)3 (55 mg, 0.060 mmol), X-Phos (60 mg, 0.12 mmol), potassium acetate (60 mg, 1.36 mmol), and 1,4-dioxane (10 mL). The system was evacuated and then refilled with N2. It was then heated at 50° C. for 2 h. After completion of the reaction, the mixture was filtered and the solid was washed with ethyl acetate (10 mL). The combined filtrate was evaporated under reduced pressure to afford 153b as a pale yellow solid, which was used in the next step. MS-ESI: [M+H]+ 305.1.
