N-Demethylation of N-methyl alkaloids with ferrocene
作者:Gaik B. Kok、Peter J. Scammells
DOI:10.1016/j.bmcl.2010.06.031
日期:2010.8
ferrocene has been found to be a convenient and efficient catalyst for the N-demethylation of a number of N-methyl alkaloids such as opiates and tropanes. By judicious choice of solvent, good yields have been obtained for dextromethorphan, codeine methyl ether, and thebaine. The current methodology is also successful for the N-demethylation of morphine, oripavine, and tropane alkaloids, producing the corresponding
An Improved Process for the N-Demethylation of Opiate Alkaloids using an Iron(II) Catalyst in Acetate Buffer
作者:Gaik Kok、Trent D. Ashton、Peter J. Scammells
DOI:10.1002/adsc.200800632
日期:2009.1
An improvedprocess to N-demethylate opiatealkaloids utilising a solution of the ferrous porphyrin, tetrasodium 5,10,15,20-tetra(4-sulfophenyl)porphyrinatoiron(II) [=Fe(II)-TPPS (8)], in acetatebuffer is described. This method provided the corresponding N-demethylated opiates in good yield with high reproducibility.
Polonovski-Type N-Demethylation of N-Methyl Alkaloids Using Substituted Ferrocene Redox Catalysts
作者:Peter Scammells、Gaik Kok
DOI:10.1055/s-0032-1316590
日期:2012.8
Various substituted ferrocenes have been trialed as catalysts in the nonclassical Polonovski reaction for N-demethylation of N-methyl alkaloids. Earlier studies suggest that conditions facilitating a higher ferrocenium ion concentration lead to superior outcomes. In this regard, the bifunctional ferrocene FcCH(2)CO(2)H, with electron donor and acceptor moieties in the same molecule, has been shown to be advantageous for use as a catalyst in the N-demethylation of a number of tertiary N-methylamines such as codeine, thebaine, and oripavine. These substrates are readily N-demethylated under mild conditions, employing sub-stoichiometric amounts of the substituted ferrocene at ambient temperature. These reactions are equally efficient in air and may also be carried out in one pot.
New Methodology for the N-Demethylation of Opiate Alkaloids
作者:Zemin Dong、Peter J. Scammells
DOI:10.1021/jo071171q
日期:2007.12.1
N-Demethylation is a key step in the preparation of a number of semisynthetic opiate pharmaceuticals. Herein we report a high-yielding, catalytic procedure for the N-demethylation of opiates which has a number of advantages over existing methods. For example, tetrasodium 5,10,15,20-tetra(4-sulfophenyl)porphyrinatoiron(II) (0.3 molar equiv) effected the transformation of codeine methyl ether to the corresponding N-nor analogue in 91% yield. The catalyst was readily removed and recycled.
Utility of iron nanoparticles and a solution-phase iron species for the N-demethylation of alkaloids
作者:Jon Kyle Awalt、Raymond Lam、Barrie Kellam、Bim Graham、Peter J. Scammells、Robert D. Singer
DOI:10.1039/c7gc00436b
日期:——
The N-demethylation of selected N-methylalkaloids using a modified Polonovski reaction can be accomplished using a novel green methodology employing nanoscale zero-valent iron, nZVI, in isopropanol. Use of nZVI promotes a much faster conversion to N-demethylated products due to much higher surface area on the metal surface as shown by SEM analysis. Rates of conversion can be further enhanced using