Ethanol → (3R,4S,5R)-5-amino-3,4-dihydroxy-cyclohex-1-enecarboxylic acid ethyl ester hydrochloride

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Reaction Conditions

Reaction Steps

In a 50 ml round bottom flask equipped with a reflux condenser, a magnetic stirrer and an inert gas supply, 1.91 g (10.0 mmol) (3R,4S,5R)-5-amino-3,4-dihydroxy-cyclohex-1-enecarboxylic acid mono hydrate was suspended with 19 ml ethanol and cooled to 0-5° C., treated slowly (3 min) with 0.80 ml (11.0 mmol) thionyl chloride, then 1.28 ml (10.0 mmol) diethyl sulfite was added, the mixture was heated to reflux for 3 hours (a gas mixture was evolved), the black reaction mixture was cooled to 20-25° C., to the black suspension, 19 ml ethyl acetate was added dropwise in the course of 30 min, then the mixture was cooled to 0-5° C. and stirred for 1 hour at 0-5° C. The black suspension was filtered, the filter cake was washed portion wise with a mixture of 6.5 ml ethanol and 6.5 ml ethylacetate. The light grey crystals were dried at 40° C./10 mbar/1 h, to obtain 1.57 g (3R,4S,5R)-5-amino-3,4-dihydroxy-cyclohex-1-enecarboxylic acid ethyl ester hydrochloride, as light grey crystals.

Provenance & Evidence