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- Concomitant polymorphism in the stereoselective of a ß-benzyl-ß-hydroxyaspartate analogue doi link

Auteur(s): Mekki S., Rolland-Fulcrand V., Bellahouel S., Van Der Lee Arie, Rolland Marc

(Article) Publié: Acta Crystallographica, vol. C67 p.301-305 (2011)


Ref HAL: hal-00606452_v1
DOI: 10.1107/SO108270111024632
Résumé:

Two concomitant polymorphs, (I) and (II), of a -benzyl- -hydroxyaspartate analogue [systematic name: dibenzyl 2-benzyl-2-hydroxy-3-(4-methylphenylsulfonamido)succinate], C32H31NO7S, crystallize from a mixture of ethyl acetate and cyclohexane at ambient temperature. The structure of (I) has triclinic (P1) symmetry and that of (II) monoclinic (P21/c) symmetry. Both crystal structures are made up of a stacking of homochiral racemic dimers (2S,3S and 2R,3R) which are internally connected by a similar R2 2(9) hydrogen-bonding pattern consisting of intermolecular N--H O andO--H O hydrogen bonds. The centroid of the racemic dimer lies on an inversion centre. The main structural difference between the two polymorphs is the conformational orientation of two of the four aromatic rings present in the molecule. Polymorph (II) is found to be twinned by reticular merohedry with twin index 3 and twin fractions 0.854 (1) and 0.146 (1).