Polypropionates are natural products that can help save lives. They are needed to make reserve antibiotics, compounds that are only ever used to treat infections caused by drug-resistant bacteria. However, synthesizing these substances in a specific variant and with a high degree of purity has been a challenge for chemists. Now, a team of researchers from the University of Bonn has found a solution: They have developed a method that allows them to produce all eight possible variants of polypropionate building blocks from one starting material in a relatively straightforward process. Their work has been published in the prestigious journal Angewandte Chemie International Edition.
What are polypropionates and why are they important?
Polypropionates are chemical compounds consisting of hydrocarbon chains with an alternating sequence of methyl and hydroxyl groups. They are found in many natural products, such as fatty acids, antibiotics, hormones, and pheromones. Some of these natural products have important biological activities, such as antibacterial, antifungal, anticancer, or anti-inflammatory effects.
However, not all polypropionates are the same. In nature, chiral compounds exist in two different variants that share the same molecular formula but are mirror images of each other, like a right and a left hand. Chemists call this “chirality”, which literally means “handedness”. The different variants can have very different properties and effects in living organisms. For example, one form of carvone smells of caraway, while the other smells of peppermint.
Therefore, when synthesizing potential drugs or natural products from polypropionates, it is crucial to use the right variant and to avoid any contamination from the other forms. This requires a high degree of selectivity and purity in the synthesis process.
How did the chemists achieve this?
The chemists from the University of Bonn used a single starting material, an alcohol, to produce all eight possible variants of polypropionate building blocks. They did this by using a technique called radical cascade reaction, which involves transferring electrons between molecules to create new bonds and structures.
The key to their success was finding the right catalysts and reaction conditions to control the outcome of the reaction. Catalysts are substances that speed up or direct chemical reactions without being consumed themselves. The researchers used two types of catalysts: metal complexes and organic radicals. By varying the type and amount of catalysts, they were able to influence the chirality and configuration of the resulting polypropionate building blocks.
The researchers also optimized the reaction conditions, such as temperature, solvent, and time, to achieve high yields and selectivities. They were able to produce each variant in more than 90% yield and more than 95% selectivity.
What are the implications of this work?
The method developed by the chemists from the University of Bonn is a significant advance in the field of organic synthesis. It allows them to produce all eight variants of polypropionate building blocks from one starting material in a relatively straightforward process. This reduces the number of steps and resources needed to synthesize these compounds.
The method also opens up new possibilities for exploring the biological activities and applications of polypropionates and their derivatives. The researchers hope that their work will inspire further studies on the synthesis and evaluation of novel natural products and potential drugs based on polypropionates.
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