Palladium-catalyzed synthesis and acetylcholinesterase inhibitory activity evaluation of 1-arylhuperzine A derivatives

A series of arylated huperzine A (HPA) derivatives (1-24) were efficiently synthesized in good yields (45-88% yields) through the late-stage modification of structurally complex natural anti-Alzheimer's disease (AD) drug huperzine A (HPA), using the palladium-catalyzed Suzuki-Miyaura cross-coupling reaction. The acetylcholinesterase (AChE) inhibitory activity of all synthesized compounds was evaluated to screen the potential anti-AD bioactive molecules. The results showed that introducing the aryl groups to C-1 position of HPA resulted in the unsatisfactory AChE inhibitory activity. The present study demonstrably verifies pyridone carbonyl group could be the necessary and unchangeable pharmacophore for maintaining HPA's anti-AChE potency, and provides the helpful information on the further research for developing anti-AD HPA analogues.

Recent Progress of Cu-Catalyzed Azide-Alkyne Cycloaddition Reactions (CuAAC) in Sustainable Solvents: Glycerol, Deep Eutectic Solvents, and Aqueous Media

This mini-review presents a general overview of the progress achieved during the last decade on the amalgamation of CuAAC processes (copper-catalyzed azide-alkyne cycloaddition) with the employment of sustainable solvents as reaction media. In most of the presented examples, the use of water, glycerol (Gly), or deep eutectic solvents (DESs) as non-conventional reaction media allowed not only to recycle the catalytic system (thus reducing the amount of the copper catalyst needed per mole of substrate), but also to achieve higher conversions and selectivities when compared with the reaction promoted in hazardous and volatile organic solvents (VOCs). Moreover, the use of the aforementioned green solvents also permits the improvement of the overall sustainability of the Cu-catalyzed 1,3-dipolar cycloaddition process, thus fulfilling several important principles of green chemistry.

DESign of Sustainable One-Pot Chemoenzymatic Organic Transformations in Deep Eutectic Solvents for the Synthesis of 1,2-Disubstituted Aromatic Olefins

The self-assembly of styrene-type olefins into the corresponding stilbenes was conveniently performed in the Deep Eutectic Solvent (DES) mixture 1ChCl/2Gly under air and in the absence of hazardous organic co-solvents using a one-pot chemo-biocatalytic route. Here, an enzymatic decarboxylation of p-hydroxycinnamic acids sequentially followed by a ruthenium-catalyzed metathesis of olefins has been investigated in DES. Moreover, and to extend the design of chemoenzymatic processes in DESs, we also coupled the aforementioned enzymatic decarboxylation reaction to now concomitant Pd-catalyzed Heck-type C-C coupling to produce biaryl derivatives under environmentally friendly reaction conditions.