Showing papers by "Ernest Wenkert published in 1976"
TL;DR: In this article, the 13 C NMR spectra of 15 neolignans of several structural types and two lignans were analyzed and their carbon shifts assigned, and the shifts of pyrogallol ether and ethyl phenyl carbinyl ether models were used in this connection.
96 citations
TL;DR: The carbon shifts of the Iboga-type alkaloids catharanthine, voacangine, coronaridine, ibogaine, dihydrocatharanthines and epiibogamine were recorded and correlated with the conformation of the natural bases.
Abstract: The carbon shifts of the Iboga-type alkaloids catharanthine, voacangine, coronaridine, ibogaine, dihydrocatharanthine and epiibogamine were recorded and correlated with the conformation of the natural bases. A 13C-NMR. analysis of heyneanine determined its C(19) configuration and a similar study of epiheyneanine proved its structure.
49 citations
TL;DR: The 13C shifts of the alkaloids roxburghine B, C, D and E were determined in this paper, and they confirmed the following configurations for the last three bases: C(18α)-normal, C( 18α)-pseudo, and C((18β)-epi-allo) respectively.
Abstract: The 13C shifts of the alkaloids roxburghine B, C, D and E are determined. They confirm the following configurations for the last three bases: C(18α)-normal, C(18α)-pseudo and C(18β)-pseudo, respectively. Roxburghine B is shown to be a C(18β)-epi-allo isomer.
10 citations