NMR Spectroscopic Studies on (exo, endo) C-2 Monosubstituted Norbornene Derivatives

Abstract

The 1H NMR spectra of C-2 monosubstituted norbornene and its derivatives are usually difficult to assign due to the anisotropy effect of norbornene ring and being a mixture of exo- and endo- isomers. Based on the preparation of configurationally pure C-2 substituted norbornene derivatives, this study assigned the 1H and 13C NMR signals of exo-5-norbornene-2-carboxylic acid, endo-5-norbornene-2-carboxylic acid, exo-5-norbornene-2-methanol and endo-5-norbornene-2-methanol by combined use of 1H NMR, DEPT135, 1H-1H COSY, 1H-13C HMQC and 1H-1H NOESY spectroscopy, and corresponding coupling constants. The effects of norbornene derivatives' C-2 substituents and their configurations on 1H NMR chemical shifts of the compunds were also investigated.

Keywords

• 5-norbornene-2-carboxylic acid
• 5-norbornene-2-methanol
• configurational isomer
• nuclear magnetic resonance (nmr)
• structural assignment