Acetic Acid → 3-Acetyl-4-hydroxy-6-methyl-5,6-dihydro-pyran-2-one

Temperatur

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

ORD-Eintrag

ord-3e2f96d4a4ae4d96b45869b978a6a7be

Quelldatensatz

uspto-grants-2005_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06861419B2