
TY  - JOUR
A1  - Culvenor, CCJ 
A1  - Heffernen, ML 
A1  - Woods, WG 
T1  - Nuclear magnetic resonance spectra of pyrrolizidine alkaloids. I. The spectra of retronecine and heliotridine
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1965
VL  - 18
IS  - 10
SP  - 1605
EP  - 1624
KW  - 
UR  - https://doi.org/10.1071/CH9651605 
N2  - The chemical shifts and coupling constants of the protons in retronecine and heliotridine are derived by detailed analysis of the nuclear magnetic resonance spectra of these compounds. The factors which influence the appearance and ease of interpretation of spectra of pyrrolizidine derivatives, principally the chemical shift difference of the H 6 protons and conformational averaging, are discussed.   The conformations of retronecine and heliotridine are discussed in relation to their coupling constants; the former compound is exo-buckled whereas the latter is a mixture of rapidly interconverting exo- and endo-buckled forms. 
ER  -

