title: Deracemization of axially chiral nicotinamides by dynamic salt formation with enantiopure dibenzoyltartaric acid (DBTA).
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.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi, Inage, Chiba, Chiba 263-8522, Japan. sakamotom@faculty.chiba-u.jp.
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Yagishita
authors.forename: Norifumi
authors.initials: N
authors.lastname: Kamataki
authors.forename: Kazuma
authors.initials: K
authors.lastname: Okamoto
authors.forename: Shota
authors.initials: S
authors.lastname: Kanno
authors.forename: Takashi
authors.initials: T
authors.lastname: Mino
authors.forename: Hyuma
authors.initials: H
authors.lastname: Masu
authors.forename: Masami
authors.initials: M
authors.lastname: Sakamoto
mesh_terms: D003460:Crystallization; D015394:Molecular Structure; D009536:Niacinamide / Q000737:chemistry; D013237:Stereoisomerism; D013644:Tartrates / Q000737:chemistry*
chemical_list: D013644:Tartrates; D009536:Niacinamide; C435201:2,3-bis(benzoyloxy)tartaric acid