Methanol → 7-Hydroxy-3-methoxy-2-benzofuran-1(3H)-one
Reaktionsgleichung
[OH:1][CH:2]1[C:11]2[C:6](=[C:7]([OH:12])[CH:8]=[CH:9][CH:10]=2)[C:4](=[O:5])[O:3]1.[CH3:13]O>S(=O)(=O)(O)O>[OH:12][C:7]1[CH:8]=[CH:9][CH:10]=[C:11]2[C:6]=1[C:4](=[O:5])[O:3][CH:2]2[O:1][CH3:13]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
4 drops of concentrated sulfuric acid are added to a solution of 2.5 g of 3,7-dihydroxyphthalide (in the form of the crude product--see Examples 105 and 106) in 70 ml of methanol and, after the subsequent addition of 3 Å molecular sieve, the mixture is left to stand for approximately 16 hours. The mixture is then filtered and the filtrate is concentrated by evaporation. The crude product, 3 g of yellow oil, is purified by chromatography (flash-chromatography) on silica gel using ethyl acetate/n-hexane (3:7) to yield 1.9 g (70% of the theoretical yield) of 7-hydroxy-3-methoxy-phthalide in the form of reddish crystals, m.p. 77°-79° C. (after crystallisation from diethyl ether/n-hexane); IR spectrum (CHCl3): C=O 1745 cm-1.