Showing papers on "Amaryllidaceae Alkaloids published in 2005"
TL;DR: Underivatised alkaloid mixtures extracted from intact plants and in vitro cultures of Leucojum aestivum (Amaryllidaceae) were investigated by capillary GC-MS and isomers of galanthamine and N-formylnorgalanthamine were well separated.
Abstract: Underivatised alkaloid mixtures extracted from intact plants and in vitro cultures of Leucojum aestivum (Amaryllidaceae) were investigated by capillary GC-MS. Excellent peak resolution for the alkaloids was exhibited and isomers of galanthamine and N-formylnorgalanthamine were well separated. Fourteen alkaloids of galanthamine, lycorine and crinane types were identified, 11 in the intact plants and eight in the in vitro cultures.
53 citations
TL;DR: In this article, two new naturally occurring amaryllidaceae alkaloids have been synthesized, using a divergent approach facilitated by the use of polymer-supported reagents and scavengers.
Abstract: Two new naturally occurring amaryllidaceae alkaloids have been synthesized, using a divergent approach facilitated by the use of polymer-supported reagents and scavengers.
42 citations
TL;DR: The stereocontrolled additions to a d -mannitol-derived γ-alkoxy-α,β-enoate with exclusive anti-selectivity is presented, well suited for the preparation of a broad range of biologically active Amaryllidaceae alkaloids and their aromatic analogues.
12 citations
TL;DR: The total synthesis of the Amaryllidaceae alkaloids dehydroanhydrolylycorine, hippadine, pratosine, assoanine and oxoassoanine was achieved from the appropriate N -benzylisatin precursors using an intramolecular, palladium catalyzed, dehydrohalogenation, biaryl synthesis reaction to establish the carbon skeleton of the natural products.
Abstract: The total synthesis of the Amaryllidaceae alkaloids dehydroanhydrolycorine, hippadine, pratosine, anhydrolycorine, assoanine, anhydrolycorin-7-one and oxoassoanine was achieved from the appropriate N -benzylisatin precursors using an intramolecular, palladium catalyzed, dehydrohalogenation, biaryl synthesis reaction to establish the carbon skeleton of the natural products. In order to avoid the formation of regioisomers in the cyclization reactions it was found necessary to incorporate the halogen on the benzyl group. Borane reduction of the 7 H -pyrrolo[3,2,1- de ]phenanthridine-4,5-dione derivatives gave 7 H -pyrrolo[3,2,1- de ]- and 4,5-dihydro-7 H -pyrrolo[3,2,1- de ]-phenanthridines (dehydroanhydrolycorine, dehydroassoanine, anhydrolycorine and assoanine). The former were readily reduced to the latter with NaCNBH 3 to give anhydrolycorine and assoanine. These compounds were then oxidized to anhydrolycorin-7-one and oxoassoanine whilst the same mixtures of borane reduction products could be oxidized to give hippadine and pratosine.
5 citations