Total synthesis of (+)-epiquinamide and (−)-epiepiquinamide from d-mannose

Quinolizidine-Type Alkaloids: Chemodiversity, Occurrence, and Bioactivity

Quinolizidine alkaloids (QAs) are nitrogen-containing compounds produced naturally as specialized metabolites distributed in plants and animals (e.g., frogs, sponges). The present review compiles the available information on the chemical diversity and biological activity of QAs reported during the last three decades. So far, 397 QAs have been isolated, gathering 20 different representative classes, including the most common such as matrine (13.6%), lupanine (9.8%), anagyrine (4.0%), sparteine (5.3%), cytisine (6.5%), tetrahydrocytisine (4.3%), lupinine (12.1%), macrocyclic bisquinolizidine (9.3%), biphenylquinolizidine lactone (7.1%), dimeric (7.1%), and other less known QAs (20.9%), which include several structural patterns of QAs. A detailed survey of the reported information about the bioactivities of these compounds indicated their potential as cytotoxic, antiviral, antimicrobial, insecticidal, anti-inflammatory, antimalarial, and antiacetylcholinesterase compounds, involving favorable putative drug-likeness scores. In this regard, research progress on the structural and biological/pharmacological diversity of QAs requires further studies oriented on expanding the chemical space to find bioactive scaffolds based on QAs for pharmacological and agrochemical applications.

Reductive Functionalization of Amides in Synthesis and for Modification of Bioactive Compounds

In this review, applications of the amide reductive functionalization methodology for the synthesis and modification of bioactive compounds are covered. A brief summary of the different protocols is presented in the introduction, followed by the synthetic application of these in late-stage functionalization, leading to known pharmaceuticals or to their derivatives, including bioisosteres, with potential higher activity as the main axis of the article. The synthetic approach to natural products based on amide reduction is also discussed; however, this is given in a condensed form focusing on recent or as yet unexplored applications due to a number of recently published excellent reviews covering this topic. The aim of this review is to illustrate the potential of reductive functionalization of amides as an elegant and useful tool in the synthesis of bioactive compounds and inspire further work in this field.

Rh-Catalyzed Hydroformylation-Initiated Bicyclization: Construction of Azabicyclic Systems

Here, we describe the recent progress toward construction of 1-azabicyclic structures using a domino hydroformylation double cyclization strategy of an amide bearing the trisubstituted alkene functionality. The method provides a rapid and atom-economic access to alkaloid structures under mild conditions, especially for quinolizidine and pyrrolidine-fused azepane skeletons with yields up to 82% and good diastereoselectivity. Subsequent oxidative cleavage conditions are developed for the synthesis of Dendrobatid alkaloid epi-epiquinamide.

Light-responsive vesicles for enantioselective release of chiral drugs prepared from a supra-amphiphilic M-helix

A kind of M-helix based vesicle with enantioselective release abilities towards racemic propranolol (a β-blocker) was presented.

Stereoselective Addition of a Lithium Anion of 1,1-Diphenyl-2-aza-pentadiene to Sulfinimines: Application to the Synthesis of (-)-Epiquinamide

The addition of a lithium anion of diphenylallylimine to nonracemic sulfinimines was investigated. It was found that the reaction with sulfinimines derived from aliphatic aldehydes afforded the products with excellent diastereoselectivity (>99:1), furnishing the product vicinal diamines in very good yields. Application of the formed product vicinal diamines was demonstrated in the total synthesis of the natural product (-)-epiquinamide.