1-(2-ethoxycarbonylpropanoyl)-L-proline tert.-butyl ester → 1-(2-ethoxycarbonylpropanoyl)-L-proline

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Reaction Steps

The ester obtained in Example 2 (5.9 g.) is dissolved in trifluoroacetic acid, the solution is kept at room temperature for one hour, and then concentrated to dryness in vacuo. The residue is dissolved in a mixture of ethyl acetate and saturated aqueous sodium bicarbonate. The aqueous phase is acidified and extracted with ethyl acetate. The ethyl acetate layer is dried over magnesium sulfate and concentrated to dryness in vacuo to obtain 1-(2-ethoxycarbonylpropanoyl)-L-proline, yield 4.1 g.

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