Resolution of malic acid by (+)-cinchonine and (-)-cinchonidine

(+)-Cinchonine and (-)-cinchonidine have been employed to resolve rac-malic acid. The resulting salts contain the D-malate anion in both cases. The cinchoninium and cinchonidinium I-malates were also crystallised, and the structures of all four salts were analysed in terms of their nonbonding interactions. All four structures display extensive hydrogen bonding, and it is shown that the D-malate salts are more efficiently packed. Key words: cinchona alkaloids, chiral discrimination, resolution, crystal structure. (+)-Cinchonine et (-)-cinchonidine ont ete utilisees pour resoudre acide rac-malique. Les sels resultants contiennent l'anion de D-malate dans les deux cas. Les cinchoninium et cinchonidinium I-malates ont egalement ete cristallisees et les structures de tous les quatre sels ont ete analyses en termes de leurs interactions non-covalente. Les quatre structures presentent etendue des liaisons hydrogene et on montre que les sels de D-malate sont plus efficacement empileme. [Traduit par la Redaction] Mots-cles: alcaloides du quinquina, discrimination chirale, resolution, structure cristalline.
Introduction Enantiomeric molecular recognition is an important aspect of supramolecular chemistry, because the phenomenon is not only of theoretical interest, (1) but is significant in many aspects of biology. In [...]