Visible light opens a route from sulfonamides to anilines

During that second event, a nitrogen atom bonds with a carbon atom in the sulfonamide. Sulfur dioxide (SO₂) clips out of the molecule. The researchers achieved this without adding a separate catalyst, which is a substance that speeds a chemical reaction without being consumed.

“The ability to perform this chemical transformation without adding any further chemical catalysts was a total surprise,” Nacsa said. “The individual processes we used are all standard chemistry, but figuring out the details of why it works this way was a challenge.”

Takeaway: The reaction joins two standard laboratory events: one strips a hydrogen proton, then visible light removes sulfur dioxide.

What changes for drug-discovery teams?

Removing sulfur can alter how a compound behaves in a biological system. Nacsa said removal of the sulfur atom dramatically changes the compound’s biological properties. For medicinal chemists, that makes the conversion more than a cosmetic rearrangement: each resulting structure still needs biological evaluation before anyone can infer whether it might become a medicine.

GSK’s computer-based modeling suggested that more than 90% of commercially available sulfonamides could be modified with the technique. Those calculations indicate the possible breadth of the reaction, but they do not show that every one of those compounds was converted successfully in the laboratory.

The team sees a route to recycle, reuse and repurpose sulfonamide libraries. For drug scientists, the proposed benefit is access to more chemical starting points, fewer synthetic steps and faster preparation of molecules for testing. The work does not yet supply a medicine; it supplies a way to make structures that medicinal chemists can evaluate.

Takeaway: Existing sulfonamide stocks could become a broader pool of candidates for biological testing.

What does the paper establish, and what remains open?

The study appeared in the Journal of the American Chemical Society in 2026 as “Photoinduced Reductive Elimination from Sulfur Enables a Unique Synthetic Valorization of Sulfonamides.” Its DOI is 10.1021/jacs.6c07120.

The team brought together chemists at Penn State; the Collegeville, Pennsylvania, team at UK-based multinational pharmaceutical and biotechnology company GlaxoSmithKline; and Florida State University:

• Penn State: Nacsa; graduate students Jaxon L. Barney, Bhargav Patel, Santino M. Servagno and Wyatt A. Gibbs; postdoctoral researcher Mrinmoy Das in Nacsa’s group; and assistant professor Elvira R. Sayfutyarova, Gibbs’s adviser.
• GlaxoSmithKline: Alexander J. Reif, Brian J. Levandowski and Michael D. VanHeyst.
• Florida State University: Somnath Das and assistant professor Bryan Kudisch.

The study shows a route for the reported sulfonamide-to-aniline conversion. It does not establish a new drug, clinical benefit, safety or effectiveness. The over-90% estimate remains a computational projection, and the team still must prepare compounds, test their biological activity and optimize promising structures before making drug claims.

Takeaway: The chemistry expands what researchers can try; therapeutic value still depends on further testing.

The method widens the menu for medicinal chemists, but only biological testing can decide whether the resulting structures become useful medicines.