Molecules 2013, 18(11), 14430-14447; doi:10.3390/molecules181114430
Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA)
1
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8522, Japan
2
Center for Analytical Instrumentation, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8522, Japan
*
Author to whom correspondence should be addressed.
Received: 15 October 2013 / Revised: 13 November 2013 / Accepted: 19 November 2013 / Published: 21 November 2013
(This article belongs to the Special Issue Dynamic Stereochemistry)
Abstract
Dynamic atroposelective resolution of chiral salts derived from oily racemic nicotinamides and enantiopure dibenzoyltartaric acid (DBTA) was achieved by crystallization. The absolute structures of the axial chiral nicotinamides were determined by X-ray structural analysis. The chirality could be controlled by the selection of enantiopure DBTA as a chiral auxiliary. The axial chirality generated by dynamic salt formation was retained for a long period after dissolving the chiral salt in solution even after removal of the chiral acid. The rate of racemization of nicotinamides could be controlled based on the temperature and solvent properties, and that of the salts was prolonged compared to free nicotinamides, as the molecular structure of the pyridinium ion in the salts was different from that of acid-free nicotinamides.Keywords:
dynamic crystallization; chiral salt; deracemization; racemization; axial chrality; nicotinamide; chiral memory; asymmetric synthesis; crystallization; DBTA
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MDPI and ACS Style
Yagishita, F.; Kamataki, N.; Okamoto, K.; Kanno, S.; Mino, T.; Masu, H.; Sakamoto, M. Deracemization of Axially Chiral Nicotinamides by Dynamic Salt Formation with Enantiopure Dibenzoyltartaric Acid (DBTA). Molecules 2013, 18, 14430-14447.
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