Chiral Recognition by ^(15)N NMR Spectroscopy. 8-Benzyl-5,6,7,8-tetrahydroquinoline

Abstract

Chiral recognition through diastereomeric complex formation with optically active solvents or solutes and detected by chemical-shift differences in ^1H or ^(19)FNMR spectroscopy has many applications, including for the determination of absolute configurations. The NMR shift differences observed in many chiral recognition experiments are not large and, because the reported changes of ^(15)N chemical shifts of pyridine-type nitrogens on hydrogen-bond formation and protonation are, respectively, usually 15-30 and ~100 ppm, it seemed possible that differential complexation between an optically active proton donor and the separate enantiomers of chiral pyridine derivatives might lead to substantial ^(15)N chemical-shift differences.

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