Hubert G. Theuns

Corypalline and O-methylcorypalline, two alkaloids from Papaver bracteatum☆

Abstract Two new Papaver alkaloids, corypalline and O -methylcorypalline, were identified from P. bracteatum . These alkaloids are considered as the biosynthetic precursors of N -methylcorydaldine in this plant.

Alkaloids of Papaver bracteatum: 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N-methylcorydaldine

Abstract Three new alkaloids have been identified from Papaver bracteatum , 14-β-hydroxycodeinone, 14-β-hydroxycodeine and N -methylcorydaldine. The presence of alpinigenine was also confirmed.

Neodihydrothebaine and bractazonine, two dibenz[d,f]azonine alkaloids of Papaver bracteatum

Two new dibenz[d,f]azonine alkaloids, neodihydrothebaine and bractazonine were isolated from Papaver bracteatum. Their possible biosynthesis from thebaine is discussed. The structures of both new alkaloids are proven by synthesis. An isomeric dibenz[d,f]azonine compound was also prepared.

Search for new natural sources of morphinans

Codeine, medically the most widely used opiate, is mostly derived from morphine, isolated from opium and poppy straw (Papaver somniferum, opium poppy). Morphine, however, is greatly misused by illegal conversion into its diacetyl-derivative: heroin. The discovery of an efficient alternative medicine or a source for codeine other than opium poppy may contribute to a curtailment of the heroin market. No major adverse properties should be present in such a new medicine or codeine source. In this paper the search for the latter is discussed with regards to the natural occurrence of morphinan derivatives and the biosynthetic pathways in available plants. Economic and social problems connected with the introduction of a new biological source for opiates are reviewed.

Alpinine, epialpinine and other alkaloids from Papaver bracteatum

Abstract Alpinine, epialpinine, muramine and protopine were identified as alkaloids of Papaver bracteatum . The earlier reported presence of alpinine is revised. The structures of codeine and neopine, earlier reported for this species, are assessed. Screening for the presence of O -methylflavinantine was negative.

Biomimetic synthesis of neodihydrothebaine and bractazonine from thebaine

Photochemical irradiation of the morphinan alkaloid thebaine 1 followed by reduction, affords the dibenz[d,f]azonine alkaloids neodihydrothebaine 2 and bractazonine 3, in a sequence paralleling the proposed biosynthesis of these alkaloids in Papaver bracteatum.

Constituents of Papaver bracteatum: O-methyl-α-thebaol and 10-n-nonacosanol. Lanthanide-induced chemical shifts in 1H NMR and 13C NMR☆

Abstract Two non-alkaloidal constituents were identified in Papaver bracteatum: O-methyl-α-thebaol and 10-n-nonacosanol. O-Methyl-α-thebaol is a new natural compound. The presence of isothebaine is confirmed. Lanthanide-induced chemical shifts can be used for the assignments of the 13C NMR chemical shifts of isothebaine and phenanthrenes. The use of lanthanide-induced chemical shifts in the identification of methoxyl resonances in 1H NMR is discussed.

A new rearrangement product of thebaine, isolated from Papaver bracteatum Lindl. Structural assignment of thebaine N-oxides

From Papaver bracteatum an unusual alkaloid is isolated: 6,7,8,9,10,14-hexadehydro-4,5-epoxy-3,6-di-methoxy-17-methylthebinan (1). This alkaloid is also obtained from the mixture of rearrangement products of one of the thebaine N-oxides. The structure of another constituent of the latter mixture is deduced to be 6,7,8,9,10,14-hexadehydro-3,6-dimethoxythebinan-4-ol (15). The presence of both thebaine N-oxides in Papaver bracteatum is confirmed, and their structures are revised on chemical and spectroscopic grounds.