The lycoctonine family of alkaloids: a stereochemical revision

Abstract

A redetermination of the structure of des(oxymethylene)lycoctonine hydriodide has shown that a wrong choice had been made between the real and false mirror image peaks for the atoms of the 1-methoxyl group in the original pseudosymmetric Fourier synthesis. It has been demonstrated that lycoctonine samples from many sources are identical, and that no rearrangement took place in forming des(oxymethylene)lycoctonine. Hence all alkaloids that have been related to lycoctonine have a 1α-methoxyl group.

The 1α-hydroxy-A-rings of norditerpenoid alkaloids are twisted-boat conformers

“…aconitine (1), lycoctonine (2), and chasmanine (4). [14][15][16][17][18][19][20] Solution conformation studies can provide detail of the bioactive conformations in biological uids of these pharmacologically important norditerpenoid alkaloids. Specically, we are studying the effects of the C1-a-oxygenated substituents on the A-rings in four selected norditerpenoid alkaloids (5)(6)(7)(8).…”

The Crystal and Molecular Structure of Hetisine Perchlorate

“…We questioned whether the reversal of the configuration occurred during the rearrangement or whether hetisine itself had a configuration different from what had been reported previously. Because an error in the X-ray structure assigned to the hydroiodide salt of 4-de(oxymethylene)lycoctonine (3) has been demonstrated recently by new X-ray analyses on lycoctonine transformation products (4,5) and by X-ray analyses of browniine perchlorate and dictyocarpine (6), we decided to carry out a new X-ray structure determination on hetisine perchorate after establishing the homogeneity of our sample of hetisine by nmr studies. This investigation confirmed the structure and stereochemistry of hetisine to be 1 as established earlier (2), clearing the way for understanding the pathway of the rearrangement reaction (1).…”

The Molecular Structures of Browniine Perchlorate and Dictyocarpine-Acetone Complex

“…group (1). Inasmuch as we have converted lycoctonine (3) (4) and browniine (4) (1) to delphatine (2) by treatment with methyl iodide and sodium hydride, the structures of these two alkaloids must also bear a 1 ct-methoxyl group (1, 5,6). To confirm this revised structure (4) for browniine, and X-ray analysis of browniine perchlorate has been carried out.…”