
%0 Journal Article
%A Ronaldson, JW 
%T Sporidesmins. XV, The <sup>13</sup>C nuclear magnetic resonance spectra of sporidesmin and sporidesmin-D. The evidence in the spectra for strain imposed by an epidithio bridge
%J Australian Journal of Chemistry
%D 1976/10/01
%V 29
%N 10
%P 2307-2314
%K 
%R https://doi.org/10.1071/CH9762307
%U https://www.publish.csiro.au/paper/CH9762307 
%X The proton-noise-decoupled 13C N.M.R. spectra of sporidesmin and sporidesmin-D are presented. The detailed assignments were worked out from the undecoupled spectrum of sporidesmin-D. The 3-methyl resonance moved downfield (by 7.3 ppm) upon cleavage of the -S-S- bridge in sporidesmin while the peaks of the two quaternary carbons to which the sulphurs are bound moved upfield (by 4.7 ppm). Lactam N-methyl and indoline N-methyl proton resonance decoupling showed that their p.m.r. assignments should be reversed. The electro-negativity of nitrogen, sulphur and carbonyl groups increased the coupling constants of the 3-CH3 by 7Hz and of the 11-CH by 10 Hz. The carbon of the lactam N-methyl was shielded by 14 ppm. There were six three-bond couplings, four HCN13C and two HCO13C, evident but no non-aromatic HCC13C couplings. 
