Pd(PPh3)2Cl2 (10 mg) in a 10 mL tube under Ar was treated sequentially with 2′-amino-6-bromo-1′-methyl-2-phenylspiro[chroman-4,4′-imidazol]-5′(1′H)-one (20 mg, 0.052 mmol) in 1,4-dioxane (1 mL), Cs2CO3 (2 N, 0.3 mL) and pyridin-3-ylboronic acid (13 mg, 0.1 mmol). The mixture was heated under microwave at 120° C. for 30 min. The reaction mixture was concentrated in vacuo to give the residue, which was purified by preparative TLC to give pure 2′-amino-1′-methyl-2-phenyl-6-(pyridin-3-yl)spiro[chroman-4,4′-imidazol]-5′(1′H)-one (18 mg, 80%). 1H-NMR (MeOD): 2.39 (t, 1H), 2.52 (dd, 1H), 3.28 (s, 3H), 5.80 (d, 1H), 7.10 (d, 1H), 7.31 (m, 2H), 7.35 (m, 2H), 7.39 (m, 3H), 7.51 (s, 1H), 7.61 (m, 2H), 8.19 (d, 1H).
