反应详情

温度

60 °C

4-Hydroxy-6-methyl-5,6-dihydro-pyran-2-one (2 g, 15.6 mmol) was combined with methylene chloride (50 mL) in a 250 mL flask and then acetic acid (17.5 M, 2 eq, 31 mmol, 1.77 mL) was added to the mixture. The mixture was cooled in an ice bath and then dicyclohexylcarbodiimide (1.3 eq, 20.3 mmol, 4.19 g) was added portionwise, followed by the addition of 4-(dimethylamino)pyridine (0.05 eq, 0.78 mmol, 88 mg) to the mixture. A sufficient amount of methylene chloride was added to ensure easy stirring and the reaction was monitored by TLC (silica gel, hexane-ethyl acetate-methylene chloride-acetone (3:3:3:1 v/v)), HPLC and LCMS as the intermediate acetic acid 2-methyl-6-oxo-3,6-dihydro-2H-pyran-4-yl ester was formed. The mixture was stirred overnight at room temperature and then toluene (20 ml) was added. The mixture was heated to 60° C. and after 48 hours the mixture was filtered, concentrated and purified by flash column chromatography to provide 3-acetyl-4-hydroxy-6-methyl-5,6-dihydro-pyran-2-one (1.02 g, 38%) as a white solid, mp 96-98° C. (lit., mp 97-98° C.). LCMS: MH+ 171.0.

1. temperatureThe mixture was cooled in an ice bath
2. customwas formed
3. stirringThe mixture was stirred overnight at room temperature
4. filtrationwas filtered
5. concentrationconcentrated
6. custompurified by flash column chromatography