Aizawa Sen-Ichi, Kidani Takahiro, Takada Sayuri, Ofusa Yumika
Graduate School of Science and Engineering, University of Toyama, Toyama, Japan.
Chirality. 2015 May;27(5):353-7. doi: 10.1002/chir.22443. Epub 2015 Apr 7.
Readily available L-tartaric acid, which is a bidentate ligand with two chiral centers forming a seven-membered chelate ring, was applied to the chiral ligand for the chiral nuclear magnetic resonance (NMR) shift reagent of samarium(III) formed in situ. This simple method does not cause serious signal broadening in the high magnetic field. Enantiomeric (13)C and (1)H NMR signals and enantiotopic (1)H NMR signals of α-amino acids were successfully resolved at pH 8.0 and the 1:3 molar ratio of Sm(NO3)3:L-tartaric acid. It is elucidated that the enantiomeric signal resolution is attributed to the anisotropic magnetic environment for the enantiomers induced by the chiral L-tartarato samarium(III) complex rather than differences in stability of the diastereomeric substrate adducts. The present (13)C NMR signal resolution was also effective for the practical simultaneous analysis of plural kinds of DL-amino acids.
易获得的L-酒石酸是一种具有两个手性中心的双齿配体，可形成七元螯合环，将其用作原位形成的钐(III)手性核磁共振(NMR)位移试剂的手性配体。这种简单方法在高磁场中不会导致严重的信号展宽。在pH 8.0以及Sm(NO3)3与L-酒石酸的摩尔比为1:3时，成功解析了α-氨基酸的对映体(13)C和(1)H NMR信号以及对映异位(1)H NMR信号。结果表明，对映体信号的解析归因于手性L-酒石酸钐(III)配合物诱导的对映体的各向异性磁环境，而非非对映体底物加合物稳定性的差异。目前的(13)C NMR信号解析对于多种DL-氨基酸的实际同时分析也有效。
