Short step enantioselective synthesis of (-)-swainsonine

Simple Indolizidine and Quinolizidine Alkaloids

This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis(quinolizidine) alkaloids.

Complementary stereocontrolled approaches to 2-pyrrolidinones bearing a vicinal amino diol subunit with three continuous chiral centers: a formal asymmetric synthesis of (-)-detoxinine

We report herein two stereocomplementary approaches to erythro/trans and threo/cis vicinal amino diol subunits containing 2-pyrrolidinones (9 and 10) starting from the known enamides 7, easily available from malimides. The first approach consists of an epoxidation-reductive dehydroxylation procedure, and the second one is based on hydroboration-oxidation reactions. Using the second method, a formal asymmetric synthesis of (-)-detoxinine was achieved.

Direct sp3 C-H bond activation adjacent to nitrogen in heterocycles

Activation of sp(3) C-H bonds adjacent to nitrogen in heterocycles is an attractive transformation that is emerging as a practical method in organic synthesis. This tutorial review aims to summarize the key examples of direct functionalization of nitrogen-containing heterocycles via metal-mediated and metal-catalyzed processes, which is meant to serve as a foundation for future investigations into this rapidly developing area of research. The review covers functionalization of N-heterocycles via alpha-lithiation with alkyllithium/diamine complexes, alpha-amino radical formation, metal-catalyzed direct C-H activation, C-H oxidations and oxidative couplings, and metal-catalyzed carbene insertions.

General Approach to Glycosidase Inhibitors. Enantioselective Synthesis of Deoxymannojirimycin and Swainsonine

[reaction: see text] Deoxymannojirimycin (2) and swainsonine (4) have been synthesized from each enantiomer of the same bicyclic carbamate precursor 7. The key intermediate was prepared by a simple and efficient three-step synthesis involving RCM of the diene 8, which in turn is easily accessible in any configuration from enantiomerically enriched 2,3-epoxy-4-penten-1-ol 9.