title: Preparation of optically active 2-aminobutanoic acid via optical resolution by replacing crystallization.
abstract: An attempt was made to use a simple procedure to obtain (R)- and (S)-2-aminobutanoic acids [(R)- and (S)-1] which are non-proteinogenic alpha-amino acids and are useful as chiral reagents in asymmetric syntheses. Compound (RS)-1 p-toluenesulfonate [(RS)-2], which is known to exist as a conglomerate, was optically resolved by replacing crystallization with (R)- and (S)-methionine p-toluenesulfonate [(R)- and (S)-3] as optically active co-solutes. When (S)-3 was employed as the co-solute, (R)-2 was preferentially crystallized from a supersaturated solution of (RS)-2 in 1-propanol, as was (S)-2 in the presence of (R)-3. (R)- and (S)-2 recrystallized from 1-propanol were treated with triethylamine in methanol to give (R)- and (S)-1 in optically pure forms.
authors.affiliation: Unit of Chemistry, Faculty of Engineering and High Technology Research Center, Kansai University, Suita, Osaka, Japan. t.yajima@ipcku.kansai-u.ac.jp
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yajima
authors.forename: Yukiyo
authors.initials: Y
authors.lastname: Aizawa
authors.forename: Mai
authors.initials: M
authors.lastname: Nishida
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sakaguchi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shiraiwa
mesh_terms: D000613:Aminobutyrates / Q000138:chemical synthesis* / Q000737:chemistry*; D003460:Crystallization; D007536:Isomerism; D019906:Nuclear Magnetic Resonance, Biomolecular; D009904:Optical Rotation; D012995:Solubility
chemical_list: D000613:Aminobutyrates; C012223:alpha-aminobutyric acid