Two 1,5-Disubstituted Proline Esters

The absolute configurations of two diastereoisomers, (2S,5R)-cis-1-benzyloxycarbonyl-5-[(2S)-hydroxy-2-phenylethyl]-2-proline tert-butyl ester (PTBEA, C₂₅H₃₁NO₅) and (2S,5R)-cis-1-benzyloxycarbonyl-5-[(2R)-hydroxy-2-phenylethyl]-2-proline tert-butyl ester (PTBEB, C₂₅H₃₁NO₅), have been established by X-ray analysis. Partial disorder of the two methylene groups of the proline ring was observed in the structure of PTBEA. In both structures, the crystal packing is controlled by an O-H...O hydrogen bond between the hydroxyl and carbonyl groups of the benzyloxycarbonyl moiety.

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