Tag Archives: Pseudoalkaloid

Exploring Caffeine to Expand the Pharmaceutical World

What do the effects of the chemicals in caffeine tell us? Researchers at the University of British Columbia, led by Dr. Laurel Schafer, answers this question, in 2019, by developing an efficient method to produce a similar chemical, known to be used in various applications. 

A starting material reacts with a chemical in a determined set of conditions to yield a single product. This product identifies itself as a class of pseudoalkaloids.

Pseudoalkaloids can be described by their use for biological activity and exhibit enhanced properties compared to alkaloids, such as cancer treatment. Pharmaceutical industries often investigate biological activities of alkaloids to use them for drugs. 

If you are a coffee lover, you probably know the naturally occurring substance, caffeine, and its stimulating properties to our nervous system. Caffeine is classified as a pseudoalkaloid.

Using a special type of reaction, these alkaloids can be created with materials that are compatible with each other. Past studies can be improved to target specific types of pseudoalkaloids by changing the materials and methods used.

Pseudoalkaloids can be artificially made, but time-consuming multiple synthetic steps limit the production of  pseudoalkaloids. Importantly, the challenge lies in the reactivity of the starting materials, and whether it can react to produce the desired pseudoalkaloid without byproducts. 

This proves to be a challenge because structurally complex or large chemicals have a hard time to mingle with their pairs. As such, this gives rise to multiple unwanted products, as seen in similar studies.

The solution lies within the tantalum catalyst, a tool that speeds up and controls the reaction, which is tested on a reaction to observe its effectiveness on producing the final product. Existing studies experimented with different types of metal catalysts and show a high potential for great results.

An idea was proposed to add molecules that bind to the tantalum catalyst. This binding molecule improves the reactivity of the catalyst and proceeds the reaction, thereby converting as much initial material as possible to the final product.

After many attempts of finding the perfect combination of chemicals to react in the optimal conditions, Dr. Laurel Schafer’s group has synthesized the desired pseudoalkaloid of interest. For public use, the product is isolated and purified easily, since the reactivity of the reaction is maximized.

The experiment is deemed successful as it tackled all the problems faced from past researchers. One example is the selectivity of the reaction, where the reaction conditions can structurally change the final product and display undesired applications.

Evidence proves the benefits of developing pseudoalkaloids, like caffeine, and hold significant demand in the public. It is possible to design synthetic methods to produce different pseudoalkaloids with caffeine in mind. 

 

 Reference

Dipucchio RC, Rosca SC, Athavan G, Schafer LL. Exploiting Natural Complexity: Synthetic Terpenoid‐Alkaloids by Regioselective and Diastereoselective Hydroaminoalkylation Catalysis. ChemCatChem. 2019;11(16):3871–6.

-Group 9 (Wilson, Young, Rachel)

 

Magical Materials Revolutionize the Pharmaceutical World

What if there’s more to caffeine than meets the eye? What if we can chemically change the way caffeine works to create a better version of itself. 

If you are a coffee lover, you probably know the naturally occurring substance, caffeine, and its stimulating properties to our nervous system. Why and how does it happen?

Using a special type of reaction, the biological activity of caffeine can be transformed to suit a variety of different applications. Past studies can be improved by changing the materials needed and the methods used. 

Dr. Schafer’s team, at the University of British Columbia, examines an approach to synthesize pseudoalkaloids (Fig. 1), chemicals present in caffeine, with great accuracy.

Figure 1. Examples of pseudoalkaloids. The pseudoalkaloids on the left are produced naturally or synthetically. The pseudoalkaloids on the right are the researchers’ target molecules. (molecules were drawn with ChemDraw 19.0; Credits: Wilson, Young, and Rachel)

Pseudoalkaloids can be artificially made, but time-consuming multiple synthetic steps limit the production of  pseudoalkaloids. Importantly, the challenge lies in the reactivity of the starting materials, and whether it can react to produce the desired pseudoalkaloid without byproducts. 

Similar studies show different products have formed, which proves to be a problem. 

Existing studies experimented with different types of metal catalysts showing potential improvement for the results. A tantalum catalyst, a tool that speeds up the reaction, is tested on a reaction to observe its effectiveness on producing the final product. 

An idea was proposed to add molecules that bind to the tantalum catalyst. This binding molecule improves the reactivity of the catalyst, thereby converting as many initial materials as possible to the final product.

Of many possible starting materials, terpenes (Fig. 2) were used for the synthesis of pseudoalkaloids. In addition to the inactive alkene groups in terpenes, various chemical structures make them attractive starting substrates to explore a new synthetic route. 

Figure 2. Examples of terpenes. Terpenes are naturally occurring organic molecules, produced by plants. The terpenes on the right are starting materials chosen by the researchers. Every terpene has unsaturated functional groups which may react with other molecules.  (molecules were drawn with ChemDraw 19.0; Credits: Wilson, Young, and Rachel)

Another key building block, an amine, can be any, as long as the nitrogen atom of an amine is directly bound to one hydrogen atom. However, a clever choice can even make the final products useful building blocks, allowing further modifications (Fig. 3)

 Figure 3. Amines with varying R groups. After reacting with a terpene, the R group of pseudoalkaloid can be further modified to form a new molecule. (molecules were drawn with ChemDraw 19.0; Credits: Wilson, Young, and Rachel)

The catalytic reaction between amines and terpenes with the tantalum catalyst showed great selectivity. Without the help of the tantalum catalyst, an amine could potentially select any active spot on a terpene and react with it, causing a mixture of pseudoalkaloids at the end of the reaction.

However, the tantalum catalyst results in one dominating product. Although the final pot contains some residual starting materials, the target pseudoalkaloids are the major product that can be easily isolated.

By constructing a pathway to ultimately arrive at the designated point, new and better options can be achieved. Caffeine is one of many that can be innovated upon.

 

Reference

Dipucchio RC, Rosca SC, Athavan G, Schafer LL. Exploiting Natural Complexity: Synthetic Terpenoid‐Alkaloids by Regioselective and Diastereoselective Hydroaminoalkylation Catalysis. ChemCatChem. 2019;11(16):3871–6.

 

-Group 9 (Wilson, Young, Rachel)

 

The magical “Ta” catalyst for pseudoalkaloids

If you are a coffee lover, you would probably know the naturally occurring substance, caffeine. But, were you aware that this substance is classified as a pseudoalkaloid?

Many pseudoalkaloids can often have biological activities like caffeine stimulates our nervous system. Ultimately, pseudoalkaloids can be used as building blocks to produce useful drugs.

In 2019, researchers at the University of British Columbia, led by Dr. Schafer, uncovered a new pathway to produce structurally simple terpenoid-alkaloids, which belong to pseudoalkaloids.

This study can be simply summarized as a reaction between a terpene and an amine with the help of a tantalum catalyst. But, let’s first explore key ingredients to deeply understand how the synthetic route works!

 

An organotantalum compound with a ureate salt
The researchers developed a catalytic reaction run by a metallic compound. Based on other known studies, they chose an organoctantalum compound to produce terpenoid-alkaloids. As like an engine is the heart of a car, the tantalum compound is an engine to drive reactions to the final products, terpenoid-alkaloids

The choice of a metallic compound is of course crucial. However, it is more important for the compound to have complete catalytic potential. How could a bare metallic compound become a complete catalyst? The answer is associating a metallic compound with a ligand such as organic molecules or salts, which can coordinate to a metal center. Of numerous possible candidates of ligands, the researchers found that a specific salt can improve the efficiency and selectivity of the bare organotantalum compound, thereby allowing it to have a complete catalytic ability.


Figure 1.The ureate salt that improved selectivity and efficiency of the organotantalum compound, Ta(CH2SiMe3)3Cl2. Of several ureate salts, the above salt was the most suitable for this study due to its solubility.

Terpenes and anilines
As the name of final products, terpenoid-alkaloids, reflects the use of terpenes, one of key ingredients is a terpene, a naturally occurring molecule. By limiting the scope of terpenes to enantiopure limonene and pinene, the types of anilines were varied and reacted with the terpenes

Now, here comes a question. What is the consequence of mixing these ingredients together?

 

Fascinating results
This study is fascinating not only for the reason that a catalytic amination of terpenes is unexplored, but also the final products are not chaotic mixtures.

What does it mean by a chaotic mixture? Some catalysts have potential to alter an intrinsic structure of a staring substance. For example, if a catalyst was able to influence the chiral center of (R)-limonene by changing its stereochemistry, a reaction batch would contain both (S) and (R)-limonenes. Consequently, the occurrence of two products is equally probable.

Also, unexplored magical ability of the tantalum catalyst in the study allows anilines to react with one specific spot of an alkene moiety in terpenes. This astonishing selectivity gives a rise to one major product.

           Figure 2.The reaction of an enantiopure limonene with six different anilines (left). The reaction of an enantiopure pinene with six different anilines (right). Both reactions result in high regio- and diastereoselectivity.

Reference
Dipucchio RC, Rosca SC, Athavan G, Schafer LL. Exploiting Natural Complexity: Synthetic Terpenoid‐Alkaloids by Regioselective and Diastereoselective Hydroaminoalkylation Catalysis. ChemCatChem. 2019;11(16):3871–6.

-Young Cho