Attrition‐Enhanced Deracemization of Axially Chiral Nicotinamides

Ishikawa, H.; Ban, Kazuma; Uemura, Naohiro; Yoshida, Yasushi; Mino, Takashi; Kasashima, Yoshio; Sakamoto, Masami

doi:10.1002/ejoc.201901826

Cited by 9 publications

(14 citation statements)

References 46 publications

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“…This unique approach has been shown to work with many chiral compounds, as summarized in Table 1. [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] F I G U R E 5 Schematic for the mechanism of attrition-enhanced deracemization. S and R represent the different absolute configuration of each enantiomer.…”

Section: Attrition-enhanced Deracemizationmentioning

confidence: 99%

“…Nicotinamides are used in biosynthesis as coenzymes for NAD/NADH and have been found to have antifungal properties. 50 Two of the screened nicotinamides showed conglomerate behavior, so the process of attrition-enhanced deracemization was attempted. Indeed, no special additives were required for racemization, that is, only heating was necessary for the process to occur.…”

Section: Recent Examples Of Attritionenhanced Deracemizationmentioning

confidence: 99%

“…Attrition-enhanced deracemization improved the enantiomeric excess of these compounds to $95% after 4 days. 50…”

Section: Recent Examples Of Attritionenhanced Deracemizationmentioning

confidence: 99%

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Recent advances in the field of chiral crystallization

Putman

Armstrong

2022

Chirality

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Crystallization is one of the largest and most economical bulk purification techniques used in industry today. There has been an increase in demand for enantiomerically pure compound production for research, organic synthesis, pharmaceutical drug production, and other applications. Even after asymmetric synthesis, chiral purification will always be necessary. The focus of this review is on recent advances in chiral crystallization for the purification of enantiomers. A comprehensive discussion of three techniques and their mechanisms is provided, namely: attrition‐enhanced deracemization, cocrystallization, and inorganic ionic cocrystallization. Several examples of attrition‐enhanced deracemization are discussed. The key advantage of this technique is that it eliminates enantiomeric waste and can be used to produce enantiomeric excesses of greater than 99% from racemic mixtures. Chiral cocrystallization is examined, with over 60 cocrystallizing compounds, as an excellent means for enantiomeric enrichment. Selective chiral inclusion complexation was shown to be a novel approach for the formation of cocrystals. Chiral inorganic ionic cocrystallization is a new technique involving the formation of cocrystals between chiral ligands and certain metal salts in order to produce conglomerate crystal behavior in otherwise racemic compounds.

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Section: Attrition-enhanced Deracemizationmentioning

confidence: 99%

Section: Recent Examples Of Attritionenhanced Deracemizationmentioning

confidence: 99%

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Recent advances in the field of chiral crystallization

Putman

Armstrong

2022

Chirality

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“…The attrition-enhanced deracemization system is named Viedma ripening, and much effort has been devoted to the development of new systems of chiral symmetry breaking using crystalline chirality. Successful examples of deracemization of amino acids, − heterocyclic compounds, − and pharmaceutically useful materials have been reported; , however, this is still a developing area and new reaction systems are eagerly awaited.…”

Section: Introductionmentioning

confidence: 99%

Chiral Symmetry Breaking of Thiohydantoins by Attrition-Enhanced Deracemization

Uemura

Hosaka

Washio

et al. 2020

Crystal Growth & Design

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Chiral symmetry breaking of thiohydantoins by attrition-enhanced deracemization was performed. It was found that three thiohydantoins afforded conglomerate crystals, and their absolute structures were determined by single crystal X-ray structure analysis. The effect of substituents on the racemization rate via a ring-opening and -closing reaction was investigated experimentally and computationally. Attrition of the crystals of racemic thiohydantoins in the presence of a catalytic amount of base promoted deracemization, leading to optically active thiohydantoins with excellent enantiomeric purity (94–96% ee) without any external chiral source.

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“…This method was developed in the deracemization of inorganic NaClO 3 crystals involving a dynamic process of crystal dissolution and growth enhanced by attrition, leading to convergence to a one-handed enantiomorphic crystal by attrition with glass beads . Much effort has been devoted to the development of new systems of chiral symmetry breaking using crystalline chirality, and successful examples of deracemization have been reported. − In this method, it is possible to achieve deracemization with high enantiomeric purity, even in a reaction with a relatively low racemization rate.…”

mentioning

confidence: 99%

Attrition-Enhanced Deracemization and Absolute Asymmetric Synthesis of Flavanones from Prochiral Precursors

Shimizu

Uemura

Yoshida

et al. 2020

Crystal Growth & Design

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Seven racemic 5,7-dimethoxyflavanones afforded conglomerate crystals upon recrystallization from a solvent. Three methodologies were investigated to achieve asymmetric transformation based on dynamic crystallization of the chiral conglomerate system. The first was chiral symmetry breaking of racemic flavanones by attrition-enhanced deracemization. Continuous suspension of racemic flavanones in a small amount of propanol in the presence of a base (1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)) and glass beads promoted chiral symmetry breaking and converted the flavanones to crystals of (+)-or (−)-enantiomers with 78 to 99% ee. The second method involved cyclization of the intermediate aldol product to give optically active flavanone with 90% ee involving a reversible oxa-Michael addition reaction with attrition-enhanced deracemization. The third was a reaction starting from prochiral 2-hydroxy-4,6dimethoxyacetophenone and 2-naphthaldehyde under basic conditions, which gave the corresponding flavanone in 89% ee.F lavanones (I) are among the most prevalent and valuable natural products, and their derivatives are widespread in many plants, fruits, vegetables, and pharmaceutical materials (Figure 1, II−IX). 1−7 Many flavanones with hydroxy or methoxy groups at the 5 and 7 positions show bioactivities, including antibacterial, antimalarial, anti-inflammatory, antipyretic, antiarrhythmic, antiasthmatic, antiulcerative, antineoplastic, and HIV-1 IN inhibitory effects. 8−14

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Attrition‐Enhanced Deracemization of Axially Chiral Nicotinamides

Cited by 9 publications

References 46 publications

Recent advances in the field of chiral crystallization

Recent advances in the field of chiral crystallization

Chiral Symmetry Breaking of Thiohydantoins by Attrition-Enhanced Deracemization

Attrition-Enhanced Deracemization and Absolute Asymmetric Synthesis of Flavanones from Prochiral Precursors

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