1-(4-Benzylthiobutanoyl)-L-proline → 4-mercaptobutanoyl-L-proline

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Reaction Steps

1-(4-Benzylthiobutanoyl)-L-proline (1.08 g.) is dissolved in a mixture of water (4 ml.) and concentrated ammonia (2.7 ml.). After one hour stirring at room temperature, the mixture is diluted with water, filtered, extracted with ethyl acetate, and the aqueous phase is concentrated in vacuo. This ammonium salt of 1-(4-mercaptobutanoyl)-L-proline is purified by ion exchange chromatography on a column of diethylaminoethyl-Sephadex (cross linked dextran) with a gradient of ammonium bicarbonate, yield 0.7 g. The ammonium salt is dissolved in water (2 ml.) and applied to a column of Dowex 50 sulfonic acid resin analytical grade in the hydrogen form, and the free acid is eluted with water. The fractions containing the desired material (sulfhydryl reagent and carboxyl reagent positive) are pooled and freeze dried to obtain 1-(4-mercaptobutanoyl)-L-proline. The dicyclohexyl ammonium salt is produced by the procedure of Example 44, m.p. 157°-158°.

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