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.

Simple indolizidine and quinolizidine alkaloids.

NSF of China [20832005]; National Basic Research Program (973 Program) of China [2010CB833200]

A flexible approach to azasugars: asymmetric total syntheses of (+)-castanospermine, (+)-7-deoxy-6-epi-castanospermine, and (+)-1-epi-castanospermine.

(1 S ,2 S ,6 R ,7 R ,8 R ,8a R )-1,2,6,7,8-Pentahydroxyindolizidine 12 and (1 R ,6 R ,7 R ,8 R ,8a R )-1,6,7,8-tetrahydroxyindolizidine (1,6-diepicastanospermine, 24 ) have been stereoselectively synthesized from the important key intermediates l,4-dideoxy-1,4-imino- d - erythro - l - altro -octitol 7 and 1,2,4-trideoxy-1,4-imino- d - glycero - d - talo -octitol 20 in three steps. Compounds 7 and 20 were readily obtained from 2,3:4,5:6,7-tri- O -isopropylidene-β- d - glycero - d - galacto -oct-4-ulo-4,8-pyranose 1 and 2-deoxy-4,5:6,7-di- O -isopropylidene-β- d - manno -oct-4-ulo-4,8-pyranose 13 in four steps, respectively.

A new and highly stereoselective synthesis of polyhydroxyindolizidines from 4-octulose derivatives

Synthesis of polyhydroxylated indolizidines and piperidines from Garner's aldehyde: total synthesis of (−)-swainsonine, (+)-1,2-di-epi-swainsonine, (+)-8,8a-di-epi-castanospermine, pentahydroxy indolizidines, (−)-1-deoxynojirimycin, (−)-1-deoxy-altro-nojirimycin, and related diversity

A concise approach to (+)-1-epi-castanospermine

Reduction of heterocyclic-derived aldol adducts 2 and 3 using NaBH(OAc)3 is stereoselective and proceeds via a hydroxy-directed mechanism to give 6 and 7, respectively, thereby complementing the stereoselectivity available with NaBH4; a synthesis of (+)-8,8a-diepicastanospermine 11 from diol 6 is described.

John K. Roberts

Papers

Hydroxy-directed ketone reduction. Application to the synthesis of (+)-8,8a-diepicastanospermine