Chemists use light to replace an oxygen atom with a nitrogen atom in a molecule

A team of chemists from the Korea Advanced Institute of Science and Technology has succeeded in extracting an oxygen atom from a molecule and replacing it with a nitrogen atom. In their study, published in the journal Sciencethe group used photocatalysis to edit a furan in their laboratory.

Ellie Plachinski and Tehshik Yoon of the University of Wisconsin-Madison published a Perspective article in the same journal issue describing the process and how it could be used to change the way drugs are made.

Previous research has shown that some complex molecules can be modified using chemical reactions, but they are rare. Chemists therefore need to synthesize molecules from scratch when they want to modify a small part of a molecule, or even a single atom, for testing purposes.

Such work has shown that even minor changes can have a major impact: as Plachinski and Yoon note, changing a single atom in a heterocycle can have a profound impact on the effectiveness of a drug. Chemists are looking for more efficient ways to modify molecules or, more precisely, remove a single atom and replace it with another.

In this new study, the research team developed a technique they describe as a pencil and eraser technique in which one atom is erased and another inscribed in pencil.

The researchers were inspired by a paper written by chemists Axel Couture and Alain Lablache-Combier in 1971, in which they used ultraviolet light to convert a furan to N-propylpyrrole to improve yield. They used ultraviolet light to exchange an oxygen atom in a furan with a nitrogen atom.

Such editing, the team notes, is particularly difficult due to relocation issues: previous attempts involved the application of high temperatures or radiation. Neither approach proved appropriate.

In this new approach, the team used light as a photocatalyst to activate a furan ring. The technique can be used to achieve single-electron oxidation on a furan, resulting in radicalization.

The approach, they note, allows for a facile reaction, sensitive to the addition of an amine. This leads to a cascade of electron and proton transfer between the product and the photocatalyst, resulting in the creation of a cyclic aldehyde intermediate.

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