Example 1 Synthesis of 2-morpholin-4-yl-6-thianthren-1-ylpyran-4-one (4): 2-chloro-6-morpholin-4-ylpyran-4-one (3) (863 mg, 4 mmol), thiophene-1-boronic acid (1.145 g, 4.4 mmol), and milled potassium carbonate (1.105 g, 8 mmol) were suspended in dioxane (10 mL) and degassed (sonicated for 5 min and subsequently saturated with N2). Tetrakis(triphenylphosphine)palladium (231 mg, 0.2 mmol) was then added and the reaction mixture was stirred vigorously at 90 °C for 24 h under N2 protection. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the residue was suspended in water (50 mL) and extracted with ethyl acetate (3 x 100 mL). The organic phases were combined, washed with saturated saline and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the residue was purified by column chromatography (silica gel; eluent: ethyl acetate/ethanol = 9:1) to afford 2-morpholin-4-yl-6-thianthren-1-ylpyran-4-one as a white solid (70 mg, 4% yield).1H NMR (300 MHz, DMSO-d6) δ: 3.44 (4H, t, J=5 Hz), 3.76 (4H, t , J=5 Hz), 5.57 (1H, d, J=2 Hz), 6.30 (1H, d, J=2 Hz), 7.43 (2H, m), 7.53 (1H, t, J=8 Hz), 7.66 (3H, m), 8.49 (1H, dd, J=1, 8 Hz). Mass spectrum (LC-MS, ESI): m/z 396 [M+H]+.
