Enantiopure O-ethyl phenylphosphonothioic acid: a solvating agent for the determination of enantiomeric excesses.
An improved method, which is highly reproducible, was developed for the enantioseparation of racemic O-ethyl phenylphosphonothioic acid (1a) with brucine by introducing seeding to a supersaturated solution of the diastereomeric salt mixture. The present method gave both diastereomeric salts in high yields with a diastereomeric ratio of >99.5:0.5 upon choosing the crystallization solvent (MeOH for the (R)-1a salt and MeOH/H2 O for the (S)-1a salt). The enantiopure acid showed a good chirality recognition ability for not only strong bases, such as amines and amino alcohols, but also weakly basic alcohols and was applicable as a solvating agent to the (1) H NMR determination of the enantiomeric excess of chiral amines, amino alcohols, and alcohols, including aliphatic substrates.
School of Environmental Science and Engineering, Kochi University of Technology, Miyanokuchi, Tosayamada, Kami, Koch, Japan.
Kazushige
K
Matsumoto
Jun
J
Sawayama
Shotaro
S
Hirao
Nagatoshi
N
Nishiwaki
Ryuichi
R
Sugimoto
Kazuhiko
K
Saigo
D005591:Chemical Fractionation / Q000379:methods*; D063085:Organothiophosphonates / Q000737:chemistry* / Q000302:isolation & purification*; D012997:Solvents / Q000737:chemistry*; D013237:Stereoisomerism
D063085:Organothiophosphonates; D012997:Solvents
1H NMR analysis; amine; amino alcohol, alcohol; diastereomeric salt formation; enantioseparation