Syntheses and 1H NMR Spectroscopic Investigations of Some Pyrrolidine Carboxylic Acids Designed as Potential Glial GABA Uptake Inhibitors.

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Abstract
The syntheses of 3-pyrroline-3-carboxylic acid (5), cis-4-hydroxypyrrolidine-3-carboxylic acid (6), 3-hydroxyoyrrolidine-3-carboxylic acid (11), pyrrolidine-3-acetic acid (homo-.beta.-proline) and cis-4-aminopyrrolidine-3-carboxylic acid (20) are described. Catalytic hydrogenation of appropriate cyclic .beta.-oxoesters are keysteps in the preparation of 5 and 6. Compound 11 was synthesized from the ketone via the corresponding protected cyanohydrin, and homo-.beta.-proline was prepared via a Knoevenagel reaction. The .beta.-amino acid 20 was prepared by stepwise hydrogenation of the enamine followed by acid treatment of the protected product. 1H-NMR spectroscopic analyses (270 MHz) were carried out to establish the relative stereochemistry of 6 and 20.