Reaktion #2122486

Reaktionsgleichung

water

4-hydroxy-8-methoxy-3-(2,4,6-trimethyl-phenyl)-1-oxa-8-aza-spiro[4.5]dec-3-en-2-one

triethylamine

ethyl chloroformate

→

carbonic acid ethyl ester 8-methoxy-2-oxo-3-(2,4,6-trimethylphenyl)-1-oxa-8-aza-spiro[4.5]dec-3-en-4-yl ester

Lösungsmittel

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   Extraktionextracted three times with ethyl acetate
2. 2
   TrocknenThe combined organic layers were dried over sodium sulfate
3. 3
   Einengenconcentrated
4. 4
   SonstigeThe crude product (brown oil) was purified by column chromatography on silica gel (ethyl acetate/cyclohexane 1:1)

Vorschrift

To a solution of crude (ca 50% purity) 4-hydroxy-8-methoxy-3-(2,4,6-trimethyl-phenyl)-1-oxa-8-aza-spiro[4.5]dec-3-en-2-one (1.0 g, 3.15 mmol), triethylamine (0.8 ml, 0.57 g, 5.67 mmol) in 6 ml THF at 0° C. under argon was added ethyl chloroformate (0.36 ml, 0.41 g, 3.78 mmol) dropwise. The suspension became immediately quite thick. It was diluted with additional 2 ml THF while stirring was continued at 0° C. for 30 minutes. The reaction mixture was poured into cold water (0° C.) and extracted three times with ethyl acetate. The combined organic layers were dried over sodium sulfate and concentrated. The crude product (brown oil) was purified by column chromatography on silica gel (ethyl acetate/cyclohexane 1:1). Yield: 220 mg of carbonic acid ethyl ester 8-methoxy-2-oxo-3-(2,4,6-trimethyl-phenyl)-1-oxa-8-aza-spiro[4.5]dec-3-en-4-yl ester (title compound P1.5) as a white solid.

Quelle