The interaction of D-penicillamine with aldehydes and ketones: 2-phenyl-5,5-dimethylthiazolidine-4-carboxylic acid

Abstract

The reaction of D-penicillamine and benzaldehyde yielded 2-phenyl-5,5-dimethylthiazolidine-4-carboxylic acid. The structure was determined by single crystal X-ray diffraction. Crystals were monoclinic, P21, a = 9.785(2), b = 6.941(1), c = 10.399(2) Å, β = 114.06(3)°, Z = 2. Intensities were measured on a Rigaku AFC6R diffractometer with Cu Kα radiation and 1881 reflections were used to determine the structure. R = 0.076, wR = 0.048. The compound exists as an amino acid in the 2S,4S configuration. The conformation of the thiazolidine ring is determined by intermolecular hydrogen bonding. Bond lengths and angles are normal. 1H and 13C NMR spectra showed that epimerization takes place in d4-CH3OH solution, and the ratio of 2S,4S diastereomer to 2R,4S diastereomer at room temperature is 65:35.