Methyl chloroformate → N-(Methoxycarbonyl)-L-tert-leucine

Participants

Reaction Conditions

Reaction Steps

23.5 ml (305 mmol) of chloroformic acid methyl ester (Fluka, Buchs, Switzerland) are added over a period of 20 minutes to a solution of 20 g (152 mmol) of (L)-tert-leucine (=2(S)-amino-3,3-dimethyl-butyric acid=L-α-tert-butylglycine; Fluka, Buchs, Switzerland) in a mixture of 252 ml (504 mmol) of 2N aqueous sodium hydroxide solution and 80 ml of dioxane and the reaction solution is heated at 60° C. for 14 hours. After the reaction solution has cooled to room temperature, it is washed twice with methylene chloride. The aqueous phase is acidified to pH 2 with 4N aqueous hydrochloric acid and extracted three times with ethyl acetate. The organic extracts are combined, dried over sodium sulfate and concentrated by evaporation, the product beginning to solidify. Digestion of the solidified solid with hexane yields the title compound in the form of a white powder. M.p. 106-108° C. 1H-NMR (CD3OD) δ=4.0 (m, 1H); 3.65 (s, 3H); 1.01 (s, 9H). Anal. (C8H15NO4.0.02 H2O) C: calc. 50.69, found 50.69; H: calc. 8.00, found 7.95; N: calc. 7.39, found 7.35.

Provenance & Evidence