(6S)-6-Isobutylpiperidine-2,4-dione and (4R,6S)/(4S,6S)-4-hydroxy-6-isobutylpiperidin-2-one.
The crystal structure of (6S)-6-isobutylpiperidine-2,4-dione, C9H15NO2, shows that the keto tautomer is favoured in the solid state. The reduction of the keto functionality leads to the corresponding 4-hydroxy-6-isobutylpiperidin-2-one, C9H17NO2, with an 84:16 cis/trans ratio, containing the 4R,6S and 4S,6S isomers; the ratio of the two isomers was determined by NMR analysis of the reaction mixture. Crystals obtained from the mixture of both isomers have been studied and shown to contain the isomers in a 86:14 ratio. Hence, both X-ray and NMR analyses show that crystallization does not select the major diastereomer formed by the reduction. In both crystal structures, the two independent molecules dimerize through an R2(2)(8) hydrogen-bond motif between adjacent amide groups.
Didierjean
Claude
C
Laboratoire de Cristallographie et Modélisation des Matériaux Minéraux et Biologiques (LCM3B), UMR No. 7036, Groupe Biocristallographie, Université Henri Poincaré, Nancy I, Faculté des Sciences,BP 239, 54506 Vandoeuvre lès Nancy CEDEX, France.
Marin
Julien
J
Wenger
Emmanuel
E
Briand
Jean Paul
JP
Aubry
André
A
Guichard
Gilles
G