1′-tert-butoxycarbonyl-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)spiro[chroman-2,4′-piperidin]-4-one (1.43 g, 3.23 mmol), 5-bromonicotinamide (778 mg, 3.87 mmol), Pd(PPh3)4 (372 mg, 0.322 mmol), and aqueous 2M Na2CO3 (10 ml) solution were suspended in dioxane (20 ml) and heated at 100° C. for 4 h. The reaction mixture was diluted with CHCl3 and H2O, the aqueous layer was extracted with CHCl3. The combined organic layer was dried over MgSO4. The desiccant was removed through celite filtration and the filtrate was concentrated under reduced pressure. The resulting residue was purified through silica gel column chromatography (EtOAc/Acetone) to obtain the intended compound as a pale yellow foam.
