To a stirred solution of (E)-4-(6-(4-dodecyloxy-3-methoxystyryl)-4-(dicyanomethylene)-4Hpyran-2-yl)-2-methoxyphenyl acetate 5c (1.40 g, 2.24 mmol) in MeOH (100 mL) at room temperature was added an excess of K2CO3 (1.50 mg, 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 (50 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 (4x50 mL). The combined organic phase was washed with water (3x50 mL) and brine (3x50 mL) then dried over Na2SO4, filtered, and evaporated under reduced pressure. Chromatography on silica gel with DCM 100% afforded the title compound 6c as an orange solid (1.28 g, 98%). Rf: 0.