Reaction #6754

Reaction equation

citric acid monohydrate

water

3-(β-D-glucopyranosyloxy)-4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methylpyrazole

ethyl chloroformate

→

3-(6-O-ethoxycarbonyl-β-D-glucopyranosyloxy)-4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methylpyrazole

Yield 72.4%

Solvents

2,4,6-trimethylpyridine

Conditions

Workup

1. 1
   workup.DISTILLATIONthe resulting mixture was purified by ODS solid phase extraction (washing solvent: distilled water, eluent: methanol)
2. 2
   OtherFurther purification by column chromatography
3. 3
   Otheron silica gel (eluent: dichloromethane/methanol=1011) and recrystalization (recrystalization solvent: ethyl acetate/hexane=1/3)

Procedure

To a solution of 3-(β-D-glucopyranosyloxy)-4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methylpyrazole (0.10 g) in 2,4,6-trimethylpyridine (1 mL) was added ethyl chloroformate (0.072 g), and the mixture was stirred at room temperature overnight. To the reaction mixture were added citric acid monohydrate (3.3 g) and water, and the resulting mixture was purified by ODS solid phase extraction (washing solvent: distilled water, eluent: methanol). Further purification by column chromatography on silica gel (eluent: dichloromethane/methanol=1011) and recrystalization (recrystalization solvent: ethyl acetate/hexane=1/3) afforded 3-(6-O-ethoxycarbonyl-β-D-glucopyranosyloxy)-4-[(4-isopropoxyphenyl)methyl]-1-isopropyl-5-methylpyrazole (0.084 g).

Source