To a stirred solution of (E)-4-(6-(4-butoxy-3-methoxystyryl)-4-(dicyanomethylene)-4H-pyran-2-yl)-2-methoxyphenyl acetate 5b (1.40 g, 2.24 mmol) in MeOH (100 mL) at room temperature was added an excess of K2CO3 (1.50 g, 10.85 mmol, 4.84 eq.) and the mixture was refluxed at 65°C during 2h (CCM, SiO2, DCM 100%). The reaction mixture was cooled to room temperature and then quenched with water (10 mL). Under stirring conditions, HCl (1M) was added to the mixture in batches and the pH value of the mixture was adjusted to 7. The crude product was extracted with DCM and the organic phase was separated. The aqueous phase was further extracted with DCM (4 x 50 mL). The combined organic phase was washed with water