A New Conformationally Restricted Aspartic Acid Analogue with a Cyclohexanone Skeleton

In the compound (1R,2S)-2-benzamido-2-methoxycarbonyl-5-oxo-1-cyclohexanecarboxylic acid, C₁₆H₁₇NO₆, the cyclohexanone ring adopts a distorted chair conformation. The carboxylic acid and the methyl ester groups occupy the axial positions, while the benzamido group is equatorial. The values determined for the torsion angles about the N—C^α(φ) and C^α—CO(ψ) bonds correspond to a semi-extended conformation for the amino acid residue. The crystal structure is stabilized by two intermolecular hydrogen bonds (O-H...O and N-H...O) involving the carboxylic acid, the benzamido and the methyl ester groups.

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