2.1.4. General Procedure for the Synthesis of Methyl (E)-4-oxo-4-Phenylbut-2-Enoates (3–4)

In a round bottom flask compound 1 or 2 (1 mmol, 1 eq) was solubilized in 5 mL of methanol and 2 drops of concentrated H₂SO₄ were added. The solution was refluxed for 2 h. The cooled solution was concentrated under vacuo and the crude was diluted with EtOAc (120 mL). The organic phase was washed with NaHCO₃ 5% (2 × 60 mL) and brine (1 × 60 mL); the organic phase was treated with Na₂SO₄, filtered and concentrated under reduced pressure. The obtained mixture was purified by flash chromatography eluting with a mixture of Cy/EtOAc (9:1).