Penn State Photochemical Method Converts Sulfonamides to Anilines Without Added Catalysts: GSK Calculations Suggest More Than 90 Percent of Commercial Sulfonamides Could Be Modified
New research led by Penn State chemists has uncovered a simple photochemical technique that converts sulfonamides into anilines, the university reported on November 11. The paper describing the research appeared in the Journal of the American Chemical Society.
Drug companies maintain large libraries of chemical compounds that can be screened for new pharmaceuticals. Sulfonamides are used in antibiotics and in drugs to treat type 2 diabetes, hypertension and inflammation. Thousands of these sulfonamides exist in these libraries, but their use beyond their initial purpose is limited because they are difficult to chemically modify. Anilines are used in other pharmaceuticals, including several cancer drugs.
Eric Nacsa, assistant professor of chemistry in the Penn State Eberly College of Science and leader of the research team, said every drug brought to market usually requires a discovery campaign involving the preparation and biological evaluation of thousands of individual molecules, and that the goal is to convert simpler existing molecules into what is wanted in fewer operations and less time.
The new method converts sulfonamides to anilines in a simple operation involving two underlying events, Nacsa explained. First, potassium phosphate removes a proton from the sulfonamide molecule. The sulfonamide is then exposed to visible light, which initiates a chemical reaction to remove another part of the molecule, completing the conversion.
Nacsa said the ability to perform this transformation without adding any further chemical catalysts was a total surprise, adding that the individual processes used are all standard chemistry, while figuring out why it works was a challenge.
Working with collaborators at Penn State, GlaxoSmithKline and Florida State University, the team showed how, after the proton is removed, light causes a nitrogen atom to bond to a carbon atom in the sulfonamide, clipping out sulfur dioxide from the molecule. Nacsa said removing the sulfur atom dramatically changes the biological properties of the compound, and that GSK computational studies suggested more than 90 percent of commercially available sulfonamides could be modified using this technique.
Published by GSM · USA (original Chinese edition)
Photo: 图：苯胺的化学结构式图，苯环连着一个氨基。Emeldir (talk) 供图，公共领域，经 Wikimedia Commons / Photo: Aniline 200. By Emeldir (talk), public domain, via Wikimedia Commons
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