Search results for "Indolizidine"

A review of the pharmacology and toxicology ofAstragalus

1997

Some Astragalus species are used as forage for livestock and wild animals. Many species are used in folk medicine for their hepatoprotective, antioxidative, immunostimulant, and antiviral properties, whereas others are toxic, and in many cases the toxic principles can pass to humans through milk and meat. Three groups of chemicals have been described as pharmacologically active principles: polysaccharides, saponins and phenolics. In addition, three kinds of toxic principles have been reported: indolizidine alkaloids, aliphatic nitro compounds and selenium. © 1997 John Wiley & Sons, Ltd.

ChemInform Abstract: Pyrroles and Indolizidines from Deprotonated α-(Alkylideneamino)nitriles.

2011

Polyhydroxylated indolizidine alkaloids-synthesis of dideoxycastanospermine

2009

The key transformation developed in this work is the anti-Kishi selective dihydroxylation, which proceeds by way of intramolecular participation of the nitrogen protecting group to furnish the desired stereochemistry required for castanospermine like structures. In this paper, we completed a first syn-thesis of a novel dideoxycastanospermine 6. Peer reviewed

ChemInform Abstract: Enantioselective Syntheses of 2-Alkyl-, 2,6-Dialkylpiperidines and Indolizidine Alkaloids Through Diastereoselective Mannich-Mic…

2010

A short and modular approach towards 3,5-disubstituted indolizidine alkaloids.

2016

3,5-Dialkyl indolizidines have been prepared in four linear steps from commercially available starting materials. The sequence involves two direct α-functionalization steps and a subsequent reductive amination and provides diastereoselective access to both C-3 epimers of the 5,9-trans-substituted indolizines. The naturally occurring indolizidines 195B and 223AB have been synthesized using this methodology.

Stereoselective Synthesis of Enantiomerically Pure Nupharamine Alkaloids from Castoreum

2009

An animalic note: The first total synthesis of the all-cis nupharamine 2, an alkaloid from beaver castoreum, is based on the stereoselective domino Mannich-Michael reaction of N-galactosylfurylaldimine to give 1 (Piv = pivaloyl), subsequent conjugate cuprate addition, and stereoselective protonation of the enolate. These reactions are all controlled by the carbohydrate. Protonation of the enolate after cleavage of the auxiliary leads to epimer 3.

1,2-Asymmetric Induction in Diastereo­selective Zwitterionic Aza-Claisen Rearrangements: Key Steps in Optically Active Alkaloid Synthesis

2013

The zwitterionic aza-Claisen rearrangement of optically active N-allylpyrrolidines and α-phenoxyacetyl fluorides proceeds with complete simple diastereoselectivity (internal asymmetric induction) and complete 1,2-asymmetric induction to generate a new C–C bond adjacent to a chiral C-N-Boc functionality. The resulting γ,δ-unsaturated amides were cyclised to give the corresponding pyrrolizidinones, which enabled the determination of the relative configuration of the stereotriads. Vinyl group degradation and a final lactam reduction gave an optically active analogue of (+)-petasinine (a pyrrolizidine alkaloid). Furthermore, the stereotriad-containing amides should be useful key intermediates f…