4-Toluenesulfonyl chloride → (2S)-1-(4-methylbenzenesulfonyl)pyrrolidine-2-carboxylic acid

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Reaction Steps

In this example, L-proline (11.5 g; 0.10 mole) and caustic soda (8.0 g; 0.2 moles) are dissolved in 100 ml water, and a solution of p-methylphenylsulfonyl chloride (20.9 g) dissolved in ether (80 ml) is added thereto with vigorous stirring under cooling in an ice bath (5°-10° C.). After reaction for about 5 hours, the reaction mixture is left standing, and the upper ether layer is removed. The remaining aqueous layer is admixed with 2N hydrochloric acid to adjust the pH to 3-4. After being left standing in a cool place (0°-5° C.), the deposited crystals are filtered off. The crystals are recrystallized from an aqueous 60% ethanol solution (about 200 ml), whereby p-methylphenylsulfonyl-L-proline (compound number 15; 20.1 g; m.p. 57°-59° C.) was obtained. Yield: 70%.

Provenance & Evidence