Abstract:
Proline derivatives have unique structures, and few reports have been published on the chiral identification of amino acids by nuclear magnetic resonance (NMR). The structures of two proline
N-amide conformation isomers were analyzed in detail using
1H NMR,
1H-
1H correlated spectroscopy(
1H-
1H COSY),
1H-
1H total correlation spectroscopy(
1H-
1H TOCSY),
1H-
1H nuclear overhauser effect spectroscopy(
1H-
1H NOESY),
13C NMR, distortionless enhancement by polarization transfer(DEPT135°),
1H-
13C
1H detected heteronuclear single quantum coherence(
1H-
13C HSQC) and
1H-
13C
1H detected heteronuclear multiple-bond correlation(
1H-
13C HMBC) techniques, and the positions of
1H and
13C NMR peaks of the derivatives were assigned. The co-existence of L- and
D-type cis-trans isomers in dimethylsulfoxide (DMSO) at room temperature were determined.