Chiral bis(mandelato)borate salts for resolution via metathesis crystallization

• Published in: Acta crystallographica. Section C, Crystal structure communications Vol. 73; no. Pt 8; p. 625
• Main Authors: Wong, Lawrence W Y, Kan, Jack W H, Sung, Herman H Y, Williams, Ian D
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.08.2017
• Subjects: Ammonium; Anions; Cations; Crystallization; Decomposition reactions; Lithium; Metathesis; Reagents; Salts; Solvents; ionic liquid; metathesis crystallization; spiroborate anion; chiral resolution; crystal structure; mandelic acid; solubility study
• ISSN: 0108-2701; 2053-2296; 1600-5759
• DOI: 10.1107/S2053229617009718

Spiroborate anions have potential for crystallization or resolution and chiral bis(mandelato)borate anions can be used for the efficient resolution of a diverse range of racemic cations via diastereomeric salt formation. The syntheses, X-ray crystal structures and solubilities of three chiral bis(mandelato)borate salts, namely poly[[aqua-μ -bis[(R)-mandelato]borato-lithium(I)] monohydrate], [Li(C H BO )(H O)] or Li[B(R-Man) ]·H O, (1), ammonium bis[(R)-mandelato]borate, NH ·C H BO or NH [B(R-Man) ], (2), and tetra-n-butylammonium bis[(R)-mandelato]borate, C H N ·C H BO or NBu [B(R-Man) ], (3), are reported. They all have a B configuration and show a reasonably well-conserved anion geometry. The main conformational variation is the orientation of the two phenyl groups, supporting the idea that [B(Man) ] is a semi-rigid anion. The salts are differentially soluble in a range of solvents, meaning they could be useful as reagents for resolution via a metathesis crystallization approach.