Radical cyclization of beta-aminoacrylates: synthesis of (-)-indolizidine 223AB

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.

Stereoselective synthesis of 2,3-disubstituted indoline, pyrrolidine and cyclic ether-fused 1,2-dihydroquinoline derivatives using alkyne iminium ion cyclization of vinylogous carbamates: switch of regioselectivity using an internal hydroxy group as a nucleophile

TMSOTf promoted alkyne iminium ion cyclization of vinylogous carbamates gives stereoselective access to indolines, pyrrolidines and dihydroquinolines.

Cross-coupling of cyclopropanols: concise syntheses of indolizidine 223AB and congeners

A new synthetic method for indolizidine or pyrrolizidine alkaloids based on readily available and attractively functionalized cyclopropanols, as exemplified in concise syntheses of indolizidine (-)-223AB, its 3-epimer, (-)-indolizidine 239AB, and (-)-indolizidine 239CD, is reported. This work highlights the applications of SN2' alkylation and C-acylation of cyclopropanols to meet stereochemical challenges in natural product synthesis. Also included is diastereoselective cyclization of the resulting aminoallene adduct for bicyclic ring formation.

A convenient allylsilane-N-acyliminium route toward indolizidine and quinolizidine alkaloids

This review relates all the results that we obtained in the field of the total synthesis of indolizidine and quinolizidine alkaloids using a strategy of the addition of an allylsilane on an N-acyliminium ion. In this paper, we describe the synthesis of racemic indolizidine 167B and chiral indolizidines: (-)-indolizidines 167B, 195B, 223AB, (+)-monomorine, (-)-(3R,5S,8aS)-3-butyl-5-propylindolizidine and (-)-dendroprimine. Next, we relate the synthesis that we have developed in the quinolizidines field: (±)-myrtine and epimyrtine, (±)-lasubines I and II and chiral quinolizidines: (+)-myrtine, (-)-epimyrtine, (-)-lasubines I and II and (+)-subcosine II.

A General, Convergent Strategy for the Construction of Indolizidine Alkaloids: Total Syntheses of (−)-Indolizidine 223AB and Alkaloid (−)-205B

N-Toluenesulfonyl aziridines comprise effective second electrophiles in the solvent controlled three-component linchpin union of silyl dithianes for the stereocontrolled convergent elaboration of protected 1,5-amino alcohols. This tactic, in conjunction with a one-flask sequential cyclization, constitutes an effective general strategy for the construction of indolizidine and related alkaloids, illustrated here with the total syntheses of (-)-indolizidine 223AB (1) and alkaloid (-)-205B (2).

Multicomponent Linchpin Coupling of Silyl Dithianes Employing an N-Ts Aziridine as the Second Electrophile: Synthesis of (−)-Indolizidine 223AB

[reaction: see text] An efficient, stereocontrolled assembly of the indolizidine alkaloid, (-)-indolizidine 223AB, exploiting a three-component linchpin coupling employing an N-Ts aziridine as the second electrophile, followed by a one-pot sequential construction of the indolizidine ring system, has been achieved. The longest linear sequence was 10 steps, proceeding in 10% overall yield.