Formaldehyde → 3-(5-Chlorothiophene-2-carbonyl)oxazolidine-5-carboxylic acid

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Reaction Steps

4.1 1.48 ml (19.9 mmol) of 37% aqueous formaldehyde solution are added to a solution of 2.00 g (19.0 mmol) of DL-isoserine in 10 ml of 1N aqueous sodium hydroxide solution. The resultant solution is left at 5° C. for 18 hours. A solution of 3.46 g (19.1 mmol) of 5-chlorothiophenecarbonyl chloride in 10 ml of acetone is added dropwise to this solution at an internal temperature of 0-5° C. During the dropwise addition, the pH is held at a value above 7 by addition of solid sodium hydrogencarbonate. When the addition is complete, the mixture is allowed to warm to room temperature, water is added, and the mixture is extracted with tert-butyl methyl ether The aqueous phase is acidified using 1N HCl and extracted with tert-butyl methyl ether. This organic phase is dried over sodium sulfate and evaporated, giving 3-(5-chlorothiophene-2-carbonyl)oxazolidine-5-carboxylic acid as a colourless solid; ESI 262.

Provenance & Evidence